class IO
Expect library adds the IO
instance method expect
, which does similar act to tcl's expect extension.
In order to use this method, you must require expect:
require 'expect'
Please see expect
for usage.
The IO
class is the basis for all input and output in Ruby. An I/O stream may be duplexed (that is, bidirectional), and so may use more than one native operating system stream.
Many of the examples in this section use the File
class, the only standard subclass of IO
. The two classes are closely associated. Like the File
class, the Socket
library subclasses from IO
(such as TCPSocket
or UDPSocket
).
The Kernel#open
method can create an IO
(or File
) object for these types of arguments:
-
A plain string represents a filename suitable for the underlying operating system.
-
A string starting with
"|"
indicates a subprocess. The remainder of the string following the"|"
is invoked as a process with appropriate input/output channels connected to it. -
A string equal to
"|-"
will create another Ruby instance as a subprocess.
The IO
may be opened with different file modes (read-only, write-only) and encodings for proper conversion. See IO.new
for these options. See Kernel#open
for details of the various command formats described above.
IO.popen
, the Open3
library, or Process#spawn may also be used to communicate with subprocesses through an IO
.
Ruby will convert pathnames between different operating system conventions if possible. For instance, on a Windows system the filename "/gumby/ruby/test.rb"
will be opened as "\gumby\ruby\test.rb"
. When specifying a Windows-style filename in a Ruby string, remember to escape the backslashes:
"c:\\gumby\\ruby\\test.rb"
Our examples here will use the Unix-style forward slashes; File::ALT_SEPARATOR can be used to get the platform-specific separator character.
The global constant ARGF (also accessible as $<) provides an IO-like stream which allows access to all files mentioned on the command line (or STDIN if no files are mentioned). ARGF#path and its alias ARGF#filename are provided to access the name of the file currently being read.
io/console¶ ↑
The io/console extension provides methods for interacting with the console. The console can be accessed from IO.console
or the standard input/output/error IO
objects.
Requiring io/console adds the following methods:
Example:
require 'io/console' rows, columns = $stdout.winsize puts "Your screen is #{columns} wide and #{rows} tall"
Constants
Public Class Methods
Opens the file, optionally seeks to the given offset, then returns length bytes (defaulting to the rest of the file). binread
ensures the file is closed before returning. The open mode would be “rb:ASCII-8BIT”.
IO.binread("testfile") #=> "This is line one\nThis is line two\nThis is line three\nAnd so on...\n" IO.binread("testfile", 20) #=> "This is line one\nThi" IO.binread("testfile", 20, 10) #=> "ne one\nThis is line "
static VALUE rb_io_s_binread(int argc, VALUE *argv, VALUE io) { VALUE offset; struct foreach_arg arg; rb_scan_args(argc, argv, "12", NULL, NULL, &offset); FilePathValue(argv[0]); arg.io = rb_io_open(argv[0], rb_str_new_cstr("rb:ASCII-8BIT"), Qnil, Qnil); if (NIL_P(arg.io)) return Qnil; arg.argv = argv+1; arg.argc = (argc > 1) ? 1 : 0; if (!NIL_P(offset)) { struct seek_arg sarg; int state = 0; sarg.io = arg.io; sarg.offset = offset; sarg.mode = SEEK_SET; rb_protect(seek_before_access, (VALUE)&sarg, &state); if (state) { rb_io_close(arg.io); rb_jump_tag(state); } } return rb_ensure(io_s_read, (VALUE)&arg, rb_io_close, arg.io); }
Same as IO.write
except opening the file in binary mode and ASCII-8BIT encoding (“wb:ASCII-8BIT”).
static VALUE rb_io_s_binwrite(int argc, VALUE *argv, VALUE io) { return io_s_write(argc, argv, 1); }
Returns an File
instance opened console.
If sym
is given, it will be sent to the opened console with args
and the result will be returned instead of the console IO
itself.
You must require 'io/console' to use this method.
static VALUE console_dev(int argc, VALUE *argv, VALUE klass) { VALUE con = 0; rb_io_t *fptr; VALUE sym = 0; rb_check_arity(argc, 0, UNLIMITED_ARGUMENTS); if (argc) { Check_Type(sym = argv[0], T_SYMBOL); } if (klass == rb_cIO) klass = rb_cFile; if (rb_const_defined(klass, id_console)) { con = rb_const_get(klass, id_console); if (!RB_TYPE_P(con, T_FILE) || (!(fptr = RFILE(con)->fptr) || GetReadFD(fptr) == -1)) { rb_const_remove(klass, id_console); con = 0; } } if (sym) { if (sym == ID2SYM(id_close) && argc == 1) { if (con) { rb_io_close(con); rb_const_remove(klass, id_console); con = 0; } return Qnil; } } if (!con) { VALUE args[2]; #if defined HAVE_TERMIOS_H || defined HAVE_TERMIO_H || defined HAVE_SGTTY_H # define CONSOLE_DEVICE "/dev/tty" #elif defined _WIN32 # define CONSOLE_DEVICE "con$" # define CONSOLE_DEVICE_FOR_READING "conin$" # define CONSOLE_DEVICE_FOR_WRITING "conout$" #endif #ifndef CONSOLE_DEVICE_FOR_READING # define CONSOLE_DEVICE_FOR_READING CONSOLE_DEVICE #endif #ifdef CONSOLE_DEVICE_FOR_WRITING VALUE out; rb_io_t *ofptr; #endif int fd; #ifdef CONSOLE_DEVICE_FOR_WRITING fd = rb_cloexec_open(CONSOLE_DEVICE_FOR_WRITING, O_RDWR, 0); if (fd < 0) return Qnil; rb_update_max_fd(fd); args[1] = INT2FIX(O_WRONLY); args[0] = INT2NUM(fd); out = rb_class_new_instance(2, args, klass); #endif fd = rb_cloexec_open(CONSOLE_DEVICE_FOR_READING, O_RDWR, 0); if (fd < 0) { #ifdef CONSOLE_DEVICE_FOR_WRITING rb_io_close(out); #endif return Qnil; } rb_update_max_fd(fd); args[1] = INT2FIX(O_RDWR); args[0] = INT2NUM(fd); con = rb_class_new_instance(2, args, klass); GetOpenFile(con, fptr); fptr->pathv = rb_obj_freeze(rb_str_new2(CONSOLE_DEVICE)); #ifdef CONSOLE_DEVICE_FOR_WRITING GetOpenFile(out, ofptr); ofptr->pathv = fptr->pathv; fptr->tied_io_for_writing = out; ofptr->mode |= FMODE_SYNC; #endif fptr->mode |= FMODE_SYNC; rb_const_set(klass, id_console, con); } if (sym) { return rb_f_send(argc, argv, con); } return con; }
IO.copy_stream
copies src to dst. src and dst is either a filename or an IO
.
This method returns the number of bytes copied.
If optional arguments are not given, the start position of the copy is the beginning of the filename or the current file offset of the IO
. The end position of the copy is the end of file.
If copy_length is given, No more than copy_length bytes are copied.
If src_offset is given, it specifies the start position of the copy.
When src_offset is specified and src is an IO
, IO.copy_stream
doesn't move the current file offset.
static VALUE rb_io_s_copy_stream(int argc, VALUE *argv, VALUE io) { VALUE src, dst, length, src_offset; struct copy_stream_struct st; MEMZERO(&st, struct copy_stream_struct, 1); rb_scan_args(argc, argv, "22", &src, &dst, &length, &src_offset); st.src = src; st.dst = dst; if (NIL_P(length)) st.copy_length = (off_t)-1; else st.copy_length = NUM2OFFT(length); if (NIL_P(src_offset)) st.src_offset = (off_t)-1; else st.src_offset = NUM2OFFT(src_offset); rb_fd_init(&st.fds); rb_ensure(copy_stream_body, (VALUE)&st, copy_stream_finalize, (VALUE)&st); return OFFT2NUM(st.total); }
Synonym for IO.new
.
static VALUE rb_io_s_for_fd(int argc, VALUE *argv, VALUE klass) { VALUE io = rb_obj_alloc(klass); rb_io_initialize(argc, argv, io); return io; }
Executes the block for every line in the named I/O port, where lines are separated by sep.
If no block is given, an enumerator is returned instead.
IO.foreach("testfile") {|x| print "GOT ", x }
produces:
GOT This is line one GOT This is line two GOT This is line three GOT And so on...
If the last argument is a hash, it's the keyword argument to open. See IO.read
for detail.
static VALUE rb_io_s_foreach(int argc, VALUE *argv, VALUE self) { VALUE opt; int orig_argc = argc; struct foreach_arg arg; argc = rb_scan_args(argc, argv, "13:", NULL, NULL, NULL, NULL, &opt); RETURN_ENUMERATOR(self, orig_argc, argv); open_key_args(argc, argv, opt, &arg); if (NIL_P(arg.io)) return Qnil; return rb_ensure(io_s_foreach, (VALUE)&arg, rb_io_close, arg.io); }
Returns a new IO
object (a stream) for the given integer file descriptor fd
and mode
string. opt
may be used to specify parts of mode
in a more readable fashion. See also IO.sysopen
and IO.for_fd
.
IO.new
is called by various File
and IO
opening methods such as IO::open
, Kernel#open
, and File::open
.
Open Mode¶ ↑
When mode
is an integer it must be combination of the modes defined in File::Constants
(File::RDONLY
, +File::WRONLY | File::CREAT+). See the open(2) man page for more information.
When mode
is a string it must be in one of the following forms:
fmode fmode ":" ext_enc fmode ":" ext_enc ":" int_enc fmode ":" "BOM|UTF-*"
fmode
is an IO
open mode string, ext_enc
is the external encoding for the IO
and int_enc
is the internal encoding.
IO
Open Mode¶ ↑
Ruby allows the following open modes:
"r" Read-only, starts at beginning of file (default mode). "r+" Read-write, starts at beginning of file. "w" Write-only, truncates existing file to zero length or creates a new file for writing. "w+" Read-write, truncates existing file to zero length or creates a new file for reading and writing. "a" Write-only, each write call appends data at end of file. Creates a new file for writing if file does not exist. "a+" Read-write, each write call appends data at end of file. Creates a new file for reading and writing if file does not exist.
The following modes must be used separately, and along with one or more of the modes seen above.
"b" Binary file mode Suppresses EOL <-> CRLF conversion on Windows. And sets external encoding to ASCII-8BIT unless explicitly specified. "t" Text file mode
When the open mode of original IO
is read only, the mode cannot be changed to be writable. Similarly, the open mode cannot be changed from write only to readable.
When such a change is attempted the error is raised in different locations according to the platform.
IO
Encoding
¶ ↑
When ext_enc
is specified, strings read will be tagged by the encoding when reading, and strings output will be converted to the specified encoding when writing.
When ext_enc
and int_enc
are specified read strings will be converted from ext_enc
to int_enc
upon input, and written strings will be converted from int_enc
to ext_enc
upon output. See Encoding
for further details of transcoding on input and output.
If “BOM|UTF-8”, “BOM|UTF-16LE” or “BOM|UTF16-BE” are used, Ruby checks for a Unicode BOM in the input document to help determine the encoding. For UTF-16 encodings the file open mode must be binary. When present, the BOM is stripped and the external encoding from the BOM is used. When the BOM is missing the given Unicode encoding is used as ext_enc
. (The BOM-set encoding option is case insensitive, so “bom|utf-8” is also valid.)
Options¶ ↑
opt
can be used instead of mode
for improved readability. The following keys are supported:
- :mode
-
Same as
mode
parameter - :flags
-
Specifies file open flags as integer. If
mode
parameter is given, this parameter will be bitwise-ORed. - :external_encoding
-
External encoding for the
IO
. - :internal_encoding
-
Internal encoding for the
IO
. “-” is a synonym for the default internal encoding.If the value is
nil
no conversion occurs. - :encoding
-
Specifies external and internal encodings as “extern:intern”.
- :textmode
-
If the value is truth value, same as “t” in argument
mode
. - :binmode
-
If the value is truth value, same as “b” in argument
mode
. - :autoclose
-
If the value is
false
, thefd
will be kept open after thisIO
instance gets finalized.
Also, opt
can have same keys in String#encode
for controlling conversion between the external encoding and the internal encoding.
Example 1¶ ↑
fd = IO.sysopen("/dev/tty", "w") a = IO.new(fd,"w") $stderr.puts "Hello" a.puts "World"
Produces:
Hello World
Example 2¶ ↑
require 'fcntl' fd = STDERR.fcntl(Fcntl::F_DUPFD) io = IO.new(fd, mode: 'w:UTF-16LE', cr_newline: true) io.puts "Hello, World!" fd = STDERR.fcntl(Fcntl::F_DUPFD) io = IO.new(fd, mode: 'w', cr_newline: true, external_encoding: Encoding::UTF_16LE) io.puts "Hello, World!"
Both of above print “Hello, World!” in UTF-16LE to standard error output with converting EOL generated by puts
to CR.
static VALUE rb_io_initialize(int argc, VALUE *argv, VALUE io) { VALUE fnum, vmode; rb_io_t *fp; int fd, fmode, oflags = O_RDONLY; convconfig_t convconfig; VALUE opt; #if defined(HAVE_FCNTL) && defined(F_GETFL) int ofmode; #else struct stat st; #endif argc = rb_scan_args(argc, argv, "11:", &fnum, &vmode, &opt); rb_io_extract_modeenc(&vmode, 0, opt, &oflags, &fmode, &convconfig); fd = NUM2INT(fnum); if (rb_reserved_fd_p(fd)) { rb_raise(rb_eArgError, "The given fd is not accessible because RubyVM reserves it"); } #if defined(HAVE_FCNTL) && defined(F_GETFL) oflags = fcntl(fd, F_GETFL); if (oflags == -1) rb_sys_fail(0); #else if (fstat(fd, &st) == -1) rb_sys_fail(0); #endif rb_update_max_fd(fd); #if defined(HAVE_FCNTL) && defined(F_GETFL) ofmode = rb_io_oflags_fmode(oflags); if (NIL_P(vmode)) { fmode = ofmode; } else if ((~ofmode & fmode) & FMODE_READWRITE) { VALUE error = INT2FIX(EINVAL); rb_exc_raise(rb_class_new_instance(1, &error, rb_eSystemCallError)); } #endif if (!NIL_P(opt) && rb_hash_aref(opt, sym_autoclose) == Qfalse) { fmode |= FMODE_PREP; } MakeOpenFile(io, fp); fp->fd = fd; fp->mode = fmode; fp->encs = convconfig; clear_codeconv(fp); io_check_tty(fp); if (fileno(stdin) == fd) fp->stdio_file = stdin; else if (fileno(stdout) == fd) fp->stdio_file = stdout; else if (fileno(stderr) == fd) fp->stdio_file = stderr; if (fmode & FMODE_SETENC_BY_BOM) io_set_encoding_by_bom(io); return io; }
With no associated block, IO.open
is a synonym for IO.new
. If the optional code block is given, it will be passed io
as an argument, and the IO
object will automatically be closed when the block terminates. In this instance, IO.open
returns the value of the block.
See IO.new
for a description of the fd
, mode
and opt
parameters.
static VALUE rb_io_s_open(int argc, VALUE *argv, VALUE klass) { VALUE io = rb_class_new_instance(argc, argv, klass); if (rb_block_given_p()) { return rb_ensure(rb_yield, io, io_close, io); } return io; }
Creates a pair of pipe endpoints (connected to each other) and returns them as a two-element array of IO
objects: [
read_io, write_io ]
.
If a block is given, the block is called and returns the value of the block. read_io and write_io are sent to the block as arguments. If read_io and write_io are not closed when the block exits, they are closed. i.e. closing read_io and/or write_io doesn't cause an error.
Not available on all platforms.
If an encoding (encoding name or encoding object) is specified as an optional argument, read string from pipe is tagged with the encoding specified. If the argument is a colon separated two encoding names “A:B”, the read string is converted from encoding A (external encoding) to encoding B (internal encoding), then tagged with B. If two optional arguments are specified, those must be encoding objects or encoding names, and the first one is the external encoding, and the second one is the internal encoding. If the external encoding and the internal encoding is specified, optional hash argument specify the conversion option.
In the example below, the two processes close the ends of the pipe that they are not using. This is not just a cosmetic nicety. The read end of a pipe will not generate an end of file condition if there are any writers with the pipe still open. In the case of the parent process, the rd.read
will never return if it does not first issue a wr.close
.
rd, wr = IO.pipe if fork wr.close puts "Parent got: <#{rd.read}>" rd.close Process.wait else rd.close puts "Sending message to parent" wr.write "Hi Dad" wr.close end
produces:
Sending message to parent Parent got: <Hi Dad>
static VALUE rb_io_s_pipe(int argc, VALUE *argv, VALUE klass) { int pipes[2], state; VALUE r, w, args[3], v1, v2; VALUE opt; rb_io_t *fptr, *fptr2; struct io_encoding_set_args ies_args; int fmode = 0; VALUE ret; argc = rb_scan_args(argc, argv, "02:", &v1, &v2, &opt); if (rb_pipe(pipes) == -1) rb_sys_fail(0); args[0] = klass; args[1] = INT2NUM(pipes[0]); args[2] = INT2FIX(O_RDONLY); r = rb_protect(io_new_instance, (VALUE)args, &state); if (state) { close(pipes[0]); close(pipes[1]); rb_jump_tag(state); } GetOpenFile(r, fptr); ies_args.fptr = fptr; ies_args.v1 = v1; ies_args.v2 = v2; ies_args.opt = opt; rb_protect(io_encoding_set_v, (VALUE)&ies_args, &state); if (state) { close(pipes[1]); io_close(r); rb_jump_tag(state); } args[1] = INT2NUM(pipes[1]); args[2] = INT2FIX(O_WRONLY); w = rb_protect(io_new_instance, (VALUE)args, &state); if (state) { close(pipes[1]); if (!NIL_P(r)) rb_io_close(r); rb_jump_tag(state); } GetOpenFile(w, fptr2); rb_io_synchronized(fptr2); extract_binmode(opt, &fmode); #if DEFAULT_TEXTMODE if ((fptr->mode & FMODE_TEXTMODE) && (fmode & FMODE_BINMODE)) { fptr->mode &= ~FMODE_TEXTMODE; setmode(fptr->fd, O_BINARY); } #if defined(RUBY_TEST_CRLF_ENVIRONMENT) || defined(_WIN32) if (fptr->encs.ecflags & ECONV_DEFAULT_NEWLINE_DECORATOR) { fptr->encs.ecflags |= ECONV_UNIVERSAL_NEWLINE_DECORATOR; } #endif #endif fptr->mode |= fmode; #if DEFAULT_TEXTMODE if ((fptr2->mode & FMODE_TEXTMODE) && (fmode & FMODE_BINMODE)) { fptr2->mode &= ~FMODE_TEXTMODE; setmode(fptr2->fd, O_BINARY); } #endif fptr2->mode |= fmode; ret = rb_assoc_new(r, w); if (rb_block_given_p()) { VALUE rw[2]; rw[0] = r; rw[1] = w; return rb_ensure(rb_yield, ret, pipe_pair_close, (VALUE)rw); } return ret; }
Runs the specified command as a subprocess; the subprocess's standard input and output will be connected to the returned IO
object.
The PID of the started process can be obtained by IO#pid
method.
cmd is a string or an array as follows.
cmd: "-" : fork commandline : command line string which is passed to a shell [env, cmdname, arg1, ..., opts] : command name and zero or more arguments (no shell) [env, [cmdname, argv0], arg1, ..., opts] : command name, argv[0] and zero or more arguments (no shell) (env and opts are optional.)
If cmd is a String
“-
'', then a new instance of Ruby is started as the subprocess.
If cmd is an Array
of String
, then it will be used as the subprocess's argv
bypassing a shell. The array can contains a hash at first for environments and a hash at last for options similar to spawn
.
The default mode for the new file object is “r'', but mode may be set to any of the modes listed in the description for class IO
. The last argument opt qualifies mode.
# set IO encoding IO.popen("nkf -e filename", :external_encoding=>"EUC-JP") {|nkf_io| euc_jp_string = nkf_io.read } # merge standard output and standard error using # spawn option. See the document of Kernel.spawn. IO.popen(["ls", "/", :err=>[:child, :out]]) {|ls_io| ls_result_with_error = ls_io.read } # spawn options can be mixed with IO options IO.popen(["ls", "/"], :err=>[:child, :out]) {|ls_io| ls_result_with_error = ls_io.read }
Raises exceptions which IO.pipe
and Kernel.spawn
raise.
If a block is given, Ruby will run the command as a child connected to Ruby with a pipe. Ruby's end of the pipe will be passed as a parameter to the block. At the end of block, Ruby closes the pipe and sets $?
. In this case IO.popen
returns the value of the block.
If a block is given with a cmd of “-
'', the block will be run in two separate processes: once in the parent, and once in a child. The parent process will be passed the pipe object as a parameter to the block, the child version of the block will be passed nil
, and the child's standard in and standard out will be connected to the parent through the pipe. Not available on all platforms.
f = IO.popen("uname") p f.readlines f.close puts "Parent is #{Process.pid}" IO.popen("date") {|f| puts f.gets } IO.popen("-") {|f| $stderr.puts "#{Process.pid} is here, f is #{f.inspect}"} p $? IO.popen(%w"sed -e s|^|<foo>| -e s&$&;zot;&", "r+") {|f| f.puts "bar"; f.close_write; puts f.gets }
produces:
["Linux\n"] Parent is 21346 Thu Jan 15 22:41:19 JST 2009 21346 is here, f is #<IO:fd 3> 21352 is here, f is nil #<Process::Status: pid 21352 exit 0> <foo>bar;zot;
static VALUE rb_io_s_popen(int argc, VALUE *argv, VALUE klass) { const char *modestr; VALUE pname, pmode = Qnil, port, tmp, opt = Qnil, env = Qnil, execarg_obj = Qnil; int oflags, fmode; convconfig_t convconfig; if (argc > 1 && !NIL_P(opt = rb_check_hash_type(argv[argc-1]))) --argc; if (argc > 1 && !NIL_P(env = rb_check_hash_type(argv[0]))) --argc, ++argv; switch (argc) { case 2: pmode = argv[1]; case 1: pname = argv[0]; break; default: { int ex = !NIL_P(opt); rb_error_arity(argc + ex, 1 + ex, 2 + ex); } } tmp = rb_check_array_type(pname); if (!NIL_P(tmp)) { long len = RARRAY_LEN(tmp); #if SIZEOF_LONG > SIZEOF_INT if (len > INT_MAX) { rb_raise(rb_eArgError, "too many arguments"); } #endif execarg_obj = rb_execarg_new((int)len, RARRAY_CONST_PTR(tmp), FALSE); RB_GC_GUARD(tmp); } else { SafeStringValue(pname); execarg_obj = Qnil; if (!is_popen_fork(pname)) execarg_obj = rb_execarg_new(1, &pname, TRUE); } if (!NIL_P(execarg_obj)) { if (!NIL_P(opt)) opt = rb_execarg_extract_options(execarg_obj, opt); if (!NIL_P(env)) rb_execarg_setenv(execarg_obj, env); } rb_io_extract_modeenc(&pmode, 0, opt, &oflags, &fmode, &convconfig); modestr = rb_io_oflags_modestr(oflags); port = pipe_open(execarg_obj, modestr, fmode, &convconfig); if (NIL_P(port)) { /* child */ if (rb_block_given_p()) { rb_yield(Qnil); rb_io_flush(rb_stdout); rb_io_flush(rb_stderr); _exit(0); } return Qnil; } RBASIC_SET_CLASS(port, klass); if (rb_block_given_p()) { return rb_ensure(rb_yield, port, pipe_close, port); } return port; }
Opens the file, optionally seeks to the given offset
, then returns length
bytes (defaulting to the rest of the file). read
ensures the file is closed before returning.
Options¶ ↑
The options hash accepts the following keys:
- encoding
-
string or encoding
Specifies the encoding of the read string.
encoding:
will be ignored iflength
is specified. SeeEncoding.aliases
for possible encodings. - mode
-
string
Specifies the mode argument for open(). It must start with an “r” otherwise it will cause an error. See
IO.new
for the list of possible modes. - open_args
-
array of strings
Specifies arguments for open() as an array. This key can not be used in combination with either
encoding:
ormode:
.
Examples:
IO.read("testfile") #=> "This is line one\nThis is line two\nThis is line three\nAnd so on...\n" IO.read("testfile", 20) #=> "This is line one\nThi" IO.read("testfile", 20, 10) #=> "ne one\nThis is line " IO.read("binfile", mode: "rb") #=> "\xF7\x00\x00\x0E\x12"
static VALUE rb_io_s_read(int argc, VALUE *argv, VALUE io) { VALUE opt, offset; struct foreach_arg arg; argc = rb_scan_args(argc, argv, "13:", NULL, NULL, &offset, NULL, &opt); open_key_args(argc, argv, opt, &arg); if (NIL_P(arg.io)) return Qnil; if (!NIL_P(offset)) { struct seek_arg sarg; int state = 0; sarg.io = arg.io; sarg.offset = offset; sarg.mode = SEEK_SET; rb_protect(seek_before_access, (VALUE)&sarg, &state); if (state) { rb_io_close(arg.io); rb_jump_tag(state); } if (arg.argc == 2) arg.argc = 1; } return rb_ensure(io_s_read, (VALUE)&arg, rb_io_close, arg.io); }
Reads the entire file specified by name as individual lines, and returns those lines in an array. Lines are separated by sep.
a = IO.readlines("testfile") a[0] #=> "This is line one\n"
If the last argument is a hash, it's the keyword argument to open. See IO.read
for detail.
static VALUE rb_io_s_readlines(int argc, VALUE *argv, VALUE io) { VALUE opt; struct foreach_arg arg; argc = rb_scan_args(argc, argv, "13:", NULL, NULL, NULL, NULL, &opt); open_key_args(argc, argv, opt, &arg); if (NIL_P(arg.io)) return Qnil; return rb_ensure(io_s_readlines, (VALUE)&arg, rb_io_close, arg.io); }
Calls select(2) system call. It monitors given arrays of IO
objects, waits until one or more of IO
objects are ready for reading, are ready for writing, and have pending exceptions respectively, and returns an array that contains arrays of those IO
objects. It will return nil
if optional timeout value is given and no IO
object is ready in timeout seconds.
IO.select
peeks the buffer of IO
objects for testing readability. If the IO
buffer is not empty, IO.select
immediately notifies readability. This “peek” only happens for IO
objects. It does not happen for IO-like objects such as OpenSSL::SSL::SSLSocket
.
The best way to use IO.select
is invoking it after nonblocking methods such as read_nonblock
, write_nonblock
, etc. The methods raise an exception which is extended by IO::WaitReadable
or IO::WaitWritable
. The modules notify how the caller should wait with IO.select
. If IO::WaitReadable
is raised, the caller should wait for reading. If IO::WaitWritable
is raised, the caller should wait for writing.
So, blocking read (readpartial
) can be emulated using read_nonblock
and IO.select
as follows:
begin result = io_like.read_nonblock(maxlen) rescue IO::WaitReadable IO.select([io_like]) retry rescue IO::WaitWritable IO.select(nil, [io_like]) retry end
Especially, the combination of nonblocking methods and IO.select
is preferred for IO
like objects such as OpenSSL::SSL::SSLSocket
. It has to_io
method to return underlying IO
object. IO.select
calls to_io
to obtain the file descriptor to wait.
This means that readability notified by IO.select
doesn't mean readability from OpenSSL::SSL::SSLSocket
object.
The most likely situation is that OpenSSL::SSL::SSLSocket
buffers some data. IO.select
doesn't see the buffer. So IO.select
can block when OpenSSL::SSL::SSLSocket#readpartial
doesn't block.
However, several more complicated situations exist.
SSL is a protocol which is sequence of records. The record consists of multiple bytes. So, the remote side of SSL sends a partial record, IO.select
notifies readability but OpenSSL::SSL::SSLSocket
cannot decrypt a byte and OpenSSL::SSL::SSLSocket#readpartial
will blocks.
Also, the remote side can request SSL renegotiation which forces the local SSL engine to write some data. This means OpenSSL::SSL::SSLSocket#readpartial
may invoke write
system call and it can block. In such a situation, OpenSSL::SSL::SSLSocket#read_nonblock
raises IO::WaitWritable
instead of blocking. So, the caller should wait for ready for writability as above example.
The combination of nonblocking methods and IO.select
is also useful for streams such as tty, pipe socket socket when multiple processes read from a stream.
Finally, Linux kernel developers don't guarantee that readability of select(2) means readability of following read(2) even for a single process. See select(2) manual on GNU/Linux system.
Invoking IO.select
before IO#readpartial
works well as usual. However it is not the best way to use IO.select
.
The writability notified by select(2) doesn't show how many bytes writable. IO#write
method blocks until given whole string is written. So, IO#write(two or more bytes)
can block after writability is notified by IO.select
. IO#write_nonblock
is required to avoid the blocking.
Blocking write (write
) can be emulated using write_nonblock
and IO.select
as follows: IO::WaitReadable
should also be rescued for SSL renegotiation in OpenSSL::SSL::SSLSocket
.
while 0 < string.bytesize begin written = io_like.write_nonblock(string) rescue IO::WaitReadable IO.select([io_like]) retry rescue IO::WaitWritable IO.select(nil, [io_like]) retry end string = string.byteslice(written..-1) end
Parameters¶ ↑
- read_array
-
an array of
IO
objects that wait until ready for read - write_array
-
an array of
IO
objects that wait until ready for write - error_array
-
an array of
IO
objects that wait for exceptions - timeout
-
a numeric value in second
Example¶ ↑
rp, wp = IO.pipe mesg = "ping " 100.times { # IO.select follows IO#read. Not the best way to use IO.select. rs, ws, = IO.select([rp], [wp]) if r = rs[0] ret = r.read(5) print ret case ret when /ping/ mesg = "pong\n" when /pong/ mesg = "ping " end end if w = ws[0] w.write(mesg) end }
produces:
ping pong ping pong ping pong (snipped) ping
static VALUE rb_f_select(int argc, VALUE *argv, VALUE obj) { VALUE timeout; struct select_args args; struct timeval timerec; int i; rb_scan_args(argc, argv, "13", &args.read, &args.write, &args.except, &timeout); if (NIL_P(timeout)) { args.timeout = 0; } else { timerec = rb_time_interval(timeout); args.timeout = &timerec; } for (i = 0; i < numberof(args.fdsets); ++i) rb_fd_init(&args.fdsets[i]); return rb_ensure(select_call, (VALUE)&args, select_end, (VALUE)&args); }
Opens the given path, returning the underlying file descriptor as a Fixnum
.
IO.sysopen("testfile") #=> 3
static VALUE rb_io_s_sysopen(int argc, VALUE *argv) { VALUE fname, vmode, vperm; VALUE intmode; int oflags, fd; mode_t perm; rb_scan_args(argc, argv, "12", &fname, &vmode, &vperm); FilePathValue(fname); if (NIL_P(vmode)) oflags = O_RDONLY; else if (!NIL_P(intmode = rb_check_to_integer(vmode, "to_int"))) oflags = NUM2INT(intmode); else { SafeStringValue(vmode); oflags = rb_io_modestr_oflags(StringValueCStr(vmode)); } if (NIL_P(vperm)) perm = 0666; else perm = NUM2MODET(vperm); RB_GC_GUARD(fname) = rb_str_new4(fname); fd = rb_sysopen(fname, oflags, perm); return INT2NUM(fd); }
Try to convert obj into an IO
, using to_io
method. Returns converted IO
or nil
if obj cannot be converted for any reason.
IO.try_convert(STDOUT) #=> STDOUT IO.try_convert("STDOUT") #=> nil require 'zlib' f = open("/tmp/zz.gz") #=> #<File:/tmp/zz.gz> z = Zlib::GzipReader.open(f) #=> #<Zlib::GzipReader:0x81d8744> IO.try_convert(z) #=> #<File:/tmp/zz.gz>
static VALUE rb_io_s_try_convert(VALUE dummy, VALUE io) { return rb_io_check_io(io); }
Opens the file, optionally seeks to the given offset, writes string, then returns the length written. write
ensures the file is closed before returning. If offset is not given in write mode, the file is truncated. Otherwise, it is not truncated.
If the last argument is a hash, it specifies option for internal open(). The key would be the following. open_args: is exclusive to others.
encoding: string or encoding specifies encoding of the read string. encoding will be ignored if length is specified. mode: string specifies mode argument for open(). it should start with "w" or "a" or "r+" otherwise it would cause error. perm: fixnum specifies perm argument for open(). open_args: array specifies arguments for open() as an array. IO.write("testfile", "0123456789", 20) # => 10 # File could contain: "This is line one\nThi0123456789two\nThis is line three\nAnd so on...\n" IO.write("testfile", "0123456789") #=> 10 # File would now read: "0123456789"
static VALUE rb_io_s_write(int argc, VALUE *argv, VALUE io) { return io_s_write(argc, argv, 0); }
Public Instance Methods
String Output—Writes obj to ios. obj will be converted to a string using to_s
.
$stdout << "Hello " << "world!\n"
produces:
Hello world!
VALUE rb_io_addstr(VALUE io, VALUE str) { rb_io_write(io, str); return io; }
Announce an intention to access data from the current file in a specific pattern. On platforms that do not support the posix_fadvise(2) system call, this method is a no-op.
advice is one of the following symbols:
- :normal
-
No advice to give; the default assumption for an open file.
- :sequential
-
The data will be accessed sequentially with lower offsets read before higher ones.
- :random
-
The data will be accessed in random order.
- :willneed
-
The data will be accessed in the near future.
- :dontneed
-
The data will not be accessed in the near future.
- :noreuse
-
The data will only be accessed once.
The semantics of a piece of advice are platform-dependent. See man 2 posix_fadvise for details.
“data” means the region of the current file that begins at offset and extends for len bytes. If len is 0, the region ends at the last byte of the file. By default, both offset and len are 0, meaning that the advice applies to the entire file.
If an error occurs, one of the following exceptions will be raised:
IOError
-
The
IO
stream is closed. Errno::EBADF
-
The file descriptor of the current file is invalid.
Errno::EINVAL
-
An invalid value for advice was given.
Errno::ESPIPE
-
The file descriptor of the current file refers to a FIFO or pipe. (Linux raises
Errno::EINVAL
in this case). TypeError
-
Either advice was not a
Symbol
, or one of the other arguments was not anInteger
. RangeError
-
One of the arguments given was too big/small.
- This list is not exhaustive; other
Errno
-
exceptions are also possible.
static VALUE rb_io_advise(int argc, VALUE *argv, VALUE io) { VALUE advice, offset, len; off_t off, l; rb_io_t *fptr; rb_scan_args(argc, argv, "12", &advice, &offset, &len); advice_arg_check(advice); io = GetWriteIO(io); GetOpenFile(io, fptr); off = NIL_P(offset) ? 0 : NUM2OFFT(offset); l = NIL_P(len) ? 0 : NUM2OFFT(len); #ifdef HAVE_POSIX_FADVISE return do_io_advise(fptr, advice, off, l); #else ((void)off, (void)l); /* Ignore all hint */ return Qnil; #endif }
Sets auto-close flag.
f = open("/dev/null") IO.for_fd(f.fileno) # ... f.gets # may cause IOError f = open("/dev/null") IO.for_fd(f.fileno).autoclose = true # ... f.gets # won't cause IOError
static VALUE rb_io_set_autoclose(VALUE io, VALUE autoclose) { rb_io_t *fptr; GetOpenFile(io, fptr); if (!RTEST(autoclose)) fptr->mode |= FMODE_PREP; else fptr->mode &= ~FMODE_PREP; return io; }
Returns true
if the underlying file descriptor of ios will be closed automatically at its finalization, otherwise false
.
static VALUE rb_io_autoclose_p(VALUE io) { rb_io_t *fptr = RFILE(io)->fptr; rb_io_check_closed(fptr); return (fptr->mode & FMODE_PREP) ? Qfalse : Qtrue; }
static VALUE console_beep(VALUE io) { rb_io_t *fptr; int fd; GetOpenFile(io, fptr); fd = GetWriteFD(fptr); #ifdef _WIN32 (void)fd; MessageBeep(0); #else if (write(fd, "\a", 1) < 0) rb_sys_fail(0); #endif return io; }
Puts ios into binary mode. Once a stream is in binary mode, it cannot be reset to nonbinary mode.
-
newline conversion disabled
-
encoding conversion disabled
-
content is treated as ASCII-8BIT
static VALUE rb_io_binmode_m(VALUE io) { VALUE write_io; rb_io_ascii8bit_binmode(io); write_io = GetWriteIO(io); if (write_io != io) rb_io_ascii8bit_binmode(write_io); return io; }
Returns true
if ios is binmode.
static VALUE rb_io_binmode_p(VALUE io) { rb_io_t *fptr; GetOpenFile(io, fptr); return fptr->mode & FMODE_BINMODE ? Qtrue : Qfalse; }
This is a deprecated alias for each_byte
.
static VALUE rb_io_bytes(VALUE io) { rb_warn("IO#bytes is deprecated; use #each_byte instead"); if (!rb_block_given_p()) return rb_enumeratorize(io, ID2SYM(rb_intern("each_byte")), 0, 0); return rb_io_each_byte(io); }
This is a deprecated alias for each_char
.
static VALUE rb_io_chars(VALUE io) { rb_warn("IO#chars is deprecated; use #each_char instead"); if (!rb_block_given_p()) return rb_enumeratorize(io, ID2SYM(rb_intern("each_char")), 0, 0); return rb_io_each_char(io); }
Closes ios and flushes any pending writes to the operating system. The stream is unavailable for any further data operations; an IOError
is raised if such an attempt is made. I/O streams are automatically closed when they are claimed by the garbage collector.
If ios is opened by IO.popen
, close
sets $?
.
Calling this method on closed IO
object is just ignored since Ruby 2.3.
static VALUE rb_io_close_m(VALUE io) { rb_io_t *fptr = rb_io_get_fptr(io); if (fptr->fd < 0) { return Qnil; } rb_io_close(io); return Qnil; }
Sets a close-on-exec flag.
f = open("/dev/null") f.close_on_exec = true system("cat", "/proc/self/fd/#{f.fileno}") # cat: /proc/self/fd/3: No such file or directory f.closed? #=> false
Ruby sets close-on-exec flags of all file descriptors by default since Ruby 2.0.0. So you don't need to set by yourself. Also, unsetting a close-on-exec flag can cause file descriptor leak if another thread use fork() and exec() (via system() method for example). If you really needs file descriptor inheritance to child process, use spawn()'s argument such as fd=>fd.
static VALUE rb_io_set_close_on_exec(VALUE io, VALUE arg) { int flag = RTEST(arg) ? FD_CLOEXEC : 0; rb_io_t *fptr; VALUE write_io; int fd, ret; write_io = GetWriteIO(io); if (io != write_io) { GetOpenFile(write_io, fptr); if (fptr && 0 <= (fd = fptr->fd)) { if ((ret = fcntl(fptr->fd, F_GETFD)) == -1) rb_sys_fail_path(fptr->pathv); if ((ret & FD_CLOEXEC) != flag) { ret = (ret & ~FD_CLOEXEC) | flag; ret = fcntl(fd, F_SETFD, ret); if (ret == -1) rb_sys_fail_path(fptr->pathv); } } } GetOpenFile(io, fptr); if (fptr && 0 <= (fd = fptr->fd)) { if ((ret = fcntl(fd, F_GETFD)) == -1) rb_sys_fail_path(fptr->pathv); if ((ret & FD_CLOEXEC) != flag) { ret = (ret & ~FD_CLOEXEC) | flag; ret = fcntl(fd, F_SETFD, ret); if (ret == -1) rb_sys_fail_path(fptr->pathv); } } return Qnil; }
Returns true
if ios will be closed on exec.
f = open("/dev/null") f.close_on_exec? #=> false f.close_on_exec = true f.close_on_exec? #=> true f.close_on_exec = false f.close_on_exec? #=> false
static VALUE rb_io_close_on_exec_p(VALUE io) { rb_io_t *fptr; VALUE write_io; int fd, ret; write_io = GetWriteIO(io); if (io != write_io) { GetOpenFile(write_io, fptr); if (fptr && 0 <= (fd = fptr->fd)) { if ((ret = fcntl(fd, F_GETFD)) == -1) rb_sys_fail_path(fptr->pathv); if (!(ret & FD_CLOEXEC)) return Qfalse; } } GetOpenFile(io, fptr); if (fptr && 0 <= (fd = fptr->fd)) { if ((ret = fcntl(fd, F_GETFD)) == -1) rb_sys_fail_path(fptr->pathv); if (!(ret & FD_CLOEXEC)) return Qfalse; } return Qtrue; }
Closes the read end of a duplex I/O stream (i.e., one that contains both a read and a write stream, such as a pipe). Will raise an IOError
if the stream is not duplexed.
f = IO.popen("/bin/sh","r+") f.close_read f.readlines
produces:
prog.rb:3:in `readlines': not opened for reading (IOError) from prog.rb:3
static VALUE rb_io_close_read(VALUE io) { rb_io_t *fptr; VALUE write_io; fptr = rb_io_get_fptr(rb_io_taint_check(io)); if (fptr->fd < 0) return Qnil; if (is_socket(fptr->fd, fptr->pathv)) { #ifndef SHUT_RD # define SHUT_RD 0 #endif if (shutdown(fptr->fd, SHUT_RD) < 0) rb_sys_fail_path(fptr->pathv); fptr->mode &= ~FMODE_READABLE; if (!(fptr->mode & FMODE_WRITABLE)) return rb_io_close(io); return Qnil; } write_io = GetWriteIO(io); if (io != write_io) { rb_io_t *wfptr; wfptr = rb_io_get_fptr(rb_io_taint_check(write_io)); wfptr->pid = fptr->pid; fptr->pid = 0; RFILE(io)->fptr = wfptr; /* bind to write_io temporarily to get rid of memory/fd leak */ fptr->tied_io_for_writing = 0; RFILE(write_io)->fptr = fptr; rb_io_fptr_cleanup(fptr, FALSE); /* should not finalize fptr because another thread may be reading it */ return Qnil; } if ((fptr->mode & (FMODE_DUPLEX|FMODE_WRITABLE)) == FMODE_WRITABLE) { rb_raise(rb_eIOError, "closing non-duplex IO for reading"); } return rb_io_close(io); }
Closes the write end of a duplex I/O stream (i.e., one that contains both a read and a write stream, such as a pipe). Will raise an IOError
if the stream is not duplexed.
f = IO.popen("/bin/sh","r+") f.close_write f.print "nowhere"
produces:
prog.rb:3:in `write': not opened for writing (IOError) from prog.rb:3:in `print' from prog.rb:3
static VALUE rb_io_close_write(VALUE io) { rb_io_t *fptr; VALUE write_io; write_io = GetWriteIO(io); fptr = rb_io_get_fptr(rb_io_taint_check(write_io)); if (fptr->fd < 0) return Qnil; if (is_socket(fptr->fd, fptr->pathv)) { #ifndef SHUT_WR # define SHUT_WR 1 #endif if (shutdown(fptr->fd, SHUT_WR) < 0) rb_sys_fail_path(fptr->pathv); fptr->mode &= ~FMODE_WRITABLE; if (!(fptr->mode & FMODE_READABLE)) return rb_io_close(write_io); return Qnil; } if ((fptr->mode & (FMODE_DUPLEX|FMODE_READABLE)) == FMODE_READABLE) { rb_raise(rb_eIOError, "closing non-duplex IO for writing"); } if (io != write_io) { fptr = rb_io_get_fptr(rb_io_taint_check(io)); fptr->tied_io_for_writing = 0; } rb_io_close(write_io); return Qnil; }
Returns true
if ios is completely closed (for duplex streams, both reader and writer), false
otherwise.
f = File.new("testfile") f.close #=> nil f.closed? #=> true f = IO.popen("/bin/sh","r+") f.close_write #=> nil f.closed? #=> false f.close_read #=> nil f.closed? #=> true
static VALUE rb_io_closed(VALUE io) { rb_io_t *fptr; VALUE write_io; rb_io_t *write_fptr; write_io = GetWriteIO(io); if (io != write_io) { write_fptr = RFILE(write_io)->fptr; if (write_fptr && 0 <= write_fptr->fd) { return Qfalse; } } fptr = rb_io_get_fptr(io); return 0 <= fptr->fd ? Qfalse : Qtrue; }
This is a deprecated alias for each_codepoint
.
static VALUE rb_io_codepoints(VALUE io) { rb_warn("IO#codepoints is deprecated; use #each_codepoint instead"); if (!rb_block_given_p()) return rb_enumeratorize(io, ID2SYM(rb_intern("each_codepoint")), 0, 0); return rb_io_each_codepoint(io); }
Yields self
within cooked mode.
STDIN.cooked(&:gets)
will read and return a line with echo back and line editing.
You must require 'io/console' to use this method.
static VALUE console_cooked(VALUE io) { return ttymode(io, rb_yield, set_cookedmode, NULL); }
Enables cooked mode.
If the terminal mode needs to be back, use io.cooked { … }.
You must require 'io/console' to use this method.
static VALUE console_set_cooked(VALUE io) { conmode t; rb_io_t *fptr; int fd; GetOpenFile(io, fptr); fd = GetReadFD(fptr); if (!getattr(fd, &t)) rb_sys_fail(0); set_cookedmode(&t, NULL); if (!setattr(fd, &t)) rb_sys_fail(0); return io; }
static VALUE console_cursor_pos(VALUE io) { rb_io_t *fptr; int fd; rb_console_size_t ws; GetOpenFile(io, fptr); fd = GetWriteFD(fptr); if (!GetConsoleScreenBufferInfo((HANDLE)rb_w32_get_osfhandle(fd), &ws)) { rb_syserr_fail(LAST_ERROR, 0); } return rb_assoc_new(UINT2NUM(ws.dwCursorPosition.X), UINT2NUM(ws.dwCursorPosition.Y)); }
static VALUE console_cursor_set(VALUE io, VALUE cpos) { cpos = rb_convert_type(cpos, T_ARRAY, "Array", "to_ary"); if (RARRAY_LEN(cpos) != 2) rb_raise(rb_eArgError, "expected 2D coordinate"); return console_goto(io, RARRAY_AREF(cpos, 0), RARRAY_AREF(cpos, 1)); }
Executes the block for every line in ios, where lines are separated by sep. ios must be opened for reading or an IOError
will be raised.
If no block is given, an enumerator is returned instead.
f = File.new("testfile") f.each {|line| puts "#{f.lineno}: #{line}" }
produces:
1: This is line one 2: This is line two 3: This is line three 4: And so on...
static VALUE rb_io_each_line(int argc, VALUE *argv, VALUE io) { VALUE str, rs; long limit; RETURN_ENUMERATOR(io, argc, argv); prepare_getline_args(argc, argv, &rs, &limit, io); if (limit == 0) rb_raise(rb_eArgError, "invalid limit: 0 for each_line"); while (!NIL_P(str = rb_io_getline_1(rs, limit, io))) { rb_yield(str); } return io; }
Calls the given block once for each byte (0..255) in ios, passing the byte as an argument. The stream must be opened for reading or an IOError
will be raised.
If no block is given, an enumerator is returned instead.
f = File.new("testfile") checksum = 0 f.each_byte {|x| checksum ^= x } #=> #<File:testfile> checksum #=> 12
static VALUE rb_io_each_byte(VALUE io) { rb_io_t *fptr; RETURN_ENUMERATOR(io, 0, 0); GetOpenFile(io, fptr); do { while (fptr->rbuf.len > 0) { char *p = fptr->rbuf.ptr + fptr->rbuf.off++; fptr->rbuf.len--; rb_yield(INT2FIX(*p & 0xff)); errno = 0; } rb_io_check_byte_readable(fptr); READ_CHECK(fptr); } while (io_fillbuf(fptr) >= 0); return io; }
Calls the given block once for each character in ios, passing the character as an argument. The stream must be opened for reading or an IOError
will be raised.
If no block is given, an enumerator is returned instead.
f = File.new("testfile") f.each_char {|c| print c, ' ' } #=> #<File:testfile>
static VALUE rb_io_each_char(VALUE io) { rb_io_t *fptr; rb_encoding *enc; VALUE c; RETURN_ENUMERATOR(io, 0, 0); GetOpenFile(io, fptr); rb_io_check_char_readable(fptr); enc = io_input_encoding(fptr); READ_CHECK(fptr); while (!NIL_P(c = io_getc(fptr, enc))) { rb_yield(c); } return io; }
Passes the Integer
ordinal of each character in ios, passing the codepoint as an argument. The stream must be opened for reading or an IOError
will be raised.
If no block is given, an enumerator is returned instead.
static VALUE rb_io_each_codepoint(VALUE io) { rb_io_t *fptr; rb_encoding *enc; unsigned int c; int r, n; RETURN_ENUMERATOR(io, 0, 0); GetOpenFile(io, fptr); rb_io_check_char_readable(fptr); READ_CHECK(fptr); if (NEED_READCONV(fptr)) { SET_BINARY_MODE(fptr); r = 1; /* no invalid char yet */ for (;;) { make_readconv(fptr, 0); for (;;) { if (fptr->cbuf.len) { if (fptr->encs.enc) r = rb_enc_precise_mbclen(fptr->cbuf.ptr+fptr->cbuf.off, fptr->cbuf.ptr+fptr->cbuf.off+fptr->cbuf.len, fptr->encs.enc); else r = ONIGENC_CONSTRUCT_MBCLEN_CHARFOUND(1); if (!MBCLEN_NEEDMORE_P(r)) break; if (fptr->cbuf.len == fptr->cbuf.capa) { rb_raise(rb_eIOError, "too long character"); } } if (more_char(fptr) == MORE_CHAR_FINISHED) { clear_readconv(fptr); if (!MBCLEN_CHARFOUND_P(r)) { enc = fptr->encs.enc; goto invalid; } return io; } } if (MBCLEN_INVALID_P(r)) { enc = fptr->encs.enc; goto invalid; } n = MBCLEN_CHARFOUND_LEN(r); if (fptr->encs.enc) { c = rb_enc_codepoint(fptr->cbuf.ptr+fptr->cbuf.off, fptr->cbuf.ptr+fptr->cbuf.off+fptr->cbuf.len, fptr->encs.enc); } else { c = (unsigned char)fptr->cbuf.ptr[fptr->cbuf.off]; } fptr->cbuf.off += n; fptr->cbuf.len -= n; rb_yield(UINT2NUM(c)); } } NEED_NEWLINE_DECORATOR_ON_READ_CHECK(fptr); enc = io_input_encoding(fptr); while (io_fillbuf(fptr) >= 0) { r = rb_enc_precise_mbclen(fptr->rbuf.ptr+fptr->rbuf.off, fptr->rbuf.ptr+fptr->rbuf.off+fptr->rbuf.len, enc); if (MBCLEN_CHARFOUND_P(r) && (n = MBCLEN_CHARFOUND_LEN(r)) <= fptr->rbuf.len) { c = rb_enc_codepoint(fptr->rbuf.ptr+fptr->rbuf.off, fptr->rbuf.ptr+fptr->rbuf.off+fptr->rbuf.len, enc); fptr->rbuf.off += n; fptr->rbuf.len -= n; rb_yield(UINT2NUM(c)); } else if (MBCLEN_INVALID_P(r)) { invalid: rb_raise(rb_eArgError, "invalid byte sequence in %s", rb_enc_name(enc)); } else if (MBCLEN_NEEDMORE_P(r)) { char cbuf[8], *p = cbuf; int more = MBCLEN_NEEDMORE_LEN(r); if (more > numberof(cbuf)) goto invalid; more += n = fptr->rbuf.len; if (more > numberof(cbuf)) goto invalid; while ((n = (int)read_buffered_data(p, more, fptr)) > 0 && (p += n, (more -= n) > 0)) { if (io_fillbuf(fptr) < 0) goto invalid; if ((n = fptr->rbuf.len) > more) n = more; } r = rb_enc_precise_mbclen(cbuf, p, enc); if (!MBCLEN_CHARFOUND_P(r)) goto invalid; c = rb_enc_codepoint(cbuf, p, enc); rb_yield(UINT2NUM(c)); } else { continue; } } return io; }
Executes the block for every line in ios, where lines are separated by sep. ios must be opened for reading or an IOError
will be raised.
If no block is given, an enumerator is returned instead.
f = File.new("testfile") f.each {|line| puts "#{f.lineno}: #{line}" }
produces:
1: This is line one 2: This is line two 3: This is line three 4: And so on...
static VALUE rb_io_each_line(int argc, VALUE *argv, VALUE io) { VALUE str, rs; long limit; RETURN_ENUMERATOR(io, argc, argv); prepare_getline_args(argc, argv, &rs, &limit, io); if (limit == 0) rb_raise(rb_eArgError, "invalid limit: 0 for each_line"); while (!NIL_P(str = rb_io_getline_1(rs, limit, io))) { rb_yield(str); } return io; }
Enables/disables echo back. On some platforms, all combinations of this flags and raw/cooked mode may not be valid.
You must require 'io/console' to use this method.
static VALUE console_set_echo(VALUE io, VALUE f) { conmode t; rb_io_t *fptr; int fd; GetOpenFile(io, fptr); fd = GetReadFD(fptr); if (!getattr(fd, &t)) rb_sys_fail(0); if (RTEST(f)) set_echo(&t, NULL); else set_noecho(&t, NULL); if (!setattr(fd, &t)) rb_sys_fail(0); return io; }
Returns true
if echo back is enabled.
You must require 'io/console' to use this method.
static VALUE console_echo_p(VALUE io) { conmode t; rb_io_t *fptr; int fd; GetOpenFile(io, fptr); fd = GetReadFD(fptr); if (!getattr(fd, &t)) rb_sys_fail(0); return echo_p(&t) ? Qtrue : Qfalse; }
Returns true if ios is at end of file that means there are no more data to read. The stream must be opened for reading or an IOError
will be raised.
f = File.new("testfile") dummy = f.readlines f.eof #=> true
If ios is a stream such as pipe or socket, IO#eof?
blocks until the other end sends some data or closes it.
r, w = IO.pipe Thread.new { sleep 1; w.close } r.eof? #=> true after 1 second blocking r, w = IO.pipe Thread.new { sleep 1; w.puts "a" } r.eof? #=> false after 1 second blocking r, w = IO.pipe r.eof? # blocks forever
Note that IO#eof?
reads data to the input byte buffer. So IO#sysread
may not behave as you intend with IO#eof?
, unless you call IO#rewind
first (which is not available for some streams).
VALUE rb_io_eof(VALUE io) { rb_io_t *fptr; GetOpenFile(io, fptr); rb_io_check_char_readable(fptr); if (READ_CHAR_PENDING(fptr)) return Qfalse; if (READ_DATA_PENDING(fptr)) return Qfalse; READ_CHECK(fptr); #if defined(RUBY_TEST_CRLF_ENVIRONMENT) || defined(_WIN32) if (!NEED_READCONV(fptr) && NEED_NEWLINE_DECORATOR_ON_READ(fptr)) { return eof(fptr->fd) ? Qtrue : Qfalse; } #endif if (io_fillbuf(fptr) < 0) { return Qtrue; } return Qfalse; }
Returns true if ios is at end of file that means there are no more data to read. The stream must be opened for reading or an IOError
will be raised.
f = File.new("testfile") dummy = f.readlines f.eof #=> true
If ios is a stream such as pipe or socket, IO#eof?
blocks until the other end sends some data or closes it.
r, w = IO.pipe Thread.new { sleep 1; w.close } r.eof? #=> true after 1 second blocking r, w = IO.pipe Thread.new { sleep 1; w.puts "a" } r.eof? #=> false after 1 second blocking r, w = IO.pipe r.eof? # blocks forever
Note that IO#eof?
reads data to the input byte buffer. So IO#sysread
may not behave as you intend with IO#eof?
, unless you call IO#rewind
first (which is not available for some streams).
VALUE rb_io_eof(VALUE io) { rb_io_t *fptr; GetOpenFile(io, fptr); rb_io_check_char_readable(fptr); if (READ_CHAR_PENDING(fptr)) return Qfalse; if (READ_DATA_PENDING(fptr)) return Qfalse; READ_CHECK(fptr); #if defined(RUBY_TEST_CRLF_ENVIRONMENT) || defined(_WIN32) if (!NEED_READCONV(fptr) && NEED_NEWLINE_DECORATOR_ON_READ(fptr)) { return eof(fptr->fd) ? Qtrue : Qfalse; } #endif if (io_fillbuf(fptr) < 0) { return Qtrue; } return Qfalse; }
Reads from the IO
until the given pattern
matches or the timeout
is over.
It returns an array with the read buffer, followed by the matches. If a block is given, the result is yielded to the block and returns nil.
When called without a block, it waits until the input that matches the given pattern
is obtained from the IO
or the time specified as the timeout passes. An array is returned when the pattern is obtained from the IO
. The first element of the array is the entire string obtained from the IO
until the pattern matches, followed by elements indicating which the pattern which matched to the anchor in the regular expression.
The optional timeout parameter defines, in seconds, the total time to wait for the pattern. If the timeout expires or eof is found, nil is returned or yielded. However, the buffer in a timeout session is kept for the next expect call. The default timeout is 9999999 seconds.
# File ext/pty/lib/expect.rb, line 33 def expect(pat,timeout=9999999) buf = '' case pat when String e_pat = Regexp.new(Regexp.quote(pat)) when Regexp e_pat = pat else raise TypeError, "unsupported pattern class: #{pat.class}" end @unusedBuf ||= '' while true if not @unusedBuf.empty? c = @unusedBuf.slice!(0).chr elsif !IO.select([self],nil,nil,timeout) or eof? then result = nil @unusedBuf = buf break else c = getc.chr end buf << c if $expect_verbose STDOUT.print c STDOUT.flush end if mat=e_pat.match(buf) then result = [buf,*mat.to_a[1..-1]] break end end if block_given? then yield result else return result end nil end
Returns the Encoding
object that represents the encoding of the file. If io is in write mode and no encoding is specified, returns nil
.
static VALUE rb_io_external_encoding(VALUE io) { rb_io_t *fptr; GetOpenFile(io, fptr); if (fptr->encs.enc2) { return rb_enc_from_encoding(fptr->encs.enc2); } if (fptr->mode & FMODE_WRITABLE) { if (fptr->encs.enc) return rb_enc_from_encoding(fptr->encs.enc); return Qnil; } return rb_enc_from_encoding(io_read_encoding(fptr)); }
Provides a mechanism for issuing low-level commands to control or query file-oriented I/O streams. Arguments and results are platform dependent. If arg is a number, its value is passed directly. If it is a string, it is interpreted as a binary sequence of bytes (Array#pack
might be a useful way to build this string). On Unix platforms, see fcntl(2)
for details. Not implemented on all platforms.
static VALUE rb_io_fcntl(int argc, VALUE *argv, VALUE io) { VALUE req, arg; rb_scan_args(argc, argv, "11", &req, &arg); return rb_fcntl(io, req, arg); }
Immediately writes all buffered data in ios to disk.
If the underlying operating system does not support fdatasync(2), IO#fsync
is called instead (which might raise a NotImplementedError
).
static VALUE rb_io_fdatasync(VALUE io) { rb_io_t *fptr; io = GetWriteIO(io); GetOpenFile(io, fptr); if (io_fflush(fptr) < 0) rb_sys_fail(0); if ((int)rb_thread_io_blocking_region(nogvl_fdatasync, fptr, fptr->fd) == 0) return INT2FIX(0); /* fall back */ return rb_io_fsync(io); }
Returns an integer representing the numeric file descriptor for ios.
$stdin.fileno #=> 0 $stdout.fileno #=> 1
static VALUE rb_io_fileno(VALUE io) { rb_io_t *fptr = RFILE(io)->fptr; int fd; rb_io_check_closed(fptr); fd = fptr->fd; return INT2FIX(fd); }
Flushes any buffered data within ios to the underlying operating system (note that this is Ruby internal buffering only; the OS may buffer the data as well).
$stdout.print "no newline" $stdout.flush
produces:
no newline
VALUE rb_io_flush(VALUE io) { return rb_io_flush_raw(io, 1); }
Immediately writes all buffered data in ios to disk. Note that fsync
differs from using IO#sync=
. The latter ensures that data is flushed from Ruby's buffers, but does not guarantee that the underlying operating system actually writes it to disk.
NotImplementedError
is raised if the underlying operating system does not support fsync(2).
static VALUE rb_io_fsync(VALUE io) { rb_io_t *fptr; io = GetWriteIO(io); GetOpenFile(io, fptr); if (io_fflush(fptr) < 0) rb_sys_fail(0); if ((int)rb_thread_io_blocking_region(nogvl_fsync, fptr, fptr->fd) < 0) rb_sys_fail_path(fptr->pathv); return INT2FIX(0); }
Gets the next 8-bit byte (0..255) from ios. Returns nil
if called at end of file.
f = File.new("testfile") f.getbyte #=> 84 f.getbyte #=> 104
VALUE rb_io_getbyte(VALUE io) { rb_io_t *fptr; int c; GetOpenFile(io, fptr); rb_io_check_byte_readable(fptr); READ_CHECK(fptr); if (fptr->fd == 0 && (fptr->mode & FMODE_TTY) && RB_TYPE_P(rb_stdout, T_FILE)) { rb_io_t *ofp; GetOpenFile(rb_stdout, ofp); if (ofp->mode & FMODE_TTY) { rb_io_flush(rb_stdout); } } if (io_fillbuf(fptr) < 0) { return Qnil; } fptr->rbuf.off++; fptr->rbuf.len--; c = (unsigned char)fptr->rbuf.ptr[fptr->rbuf.off-1]; return INT2FIX(c & 0xff); }
Reads a one-character string from ios. Returns nil
if called at end of file.
f = File.new("testfile") f.getc #=> "h" f.getc #=> "e"
static VALUE rb_io_getc(VALUE io) { rb_io_t *fptr; rb_encoding *enc; GetOpenFile(io, fptr); rb_io_check_char_readable(fptr); enc = io_input_encoding(fptr); READ_CHECK(fptr); return io_getc(fptr, enc); }
Reads and returns a character in raw mode.
You must require 'io/console' to use this method.
static VALUE console_getch(int argc, VALUE *argv, VALUE io) { rawmode_arg_t opts, *optp = rawmode_opt(argc, argv, &opts); return ttymode(io, getc_call, set_rawmode, optp); }
Reads and returns a line without echo back. Prints prompt
unless it is nil
.
You must require 'io/console' to use this method.
static VALUE console_getpass(int argc, VALUE *argv, VALUE io) { VALUE str, wio; rb_check_arity(argc, 0, 1); wio = rb_io_get_write_io(io); if (wio == io && io == rb_stdin) wio = rb_stderr; prompt(argc, argv, wio); str = rb_ensure(getpass_call, io, puts_call, wio); return str_chomp(str); }
Reads the next “line'' from the I/O stream; lines are separated by sep. A separator of nil
reads the entire contents, and a zero-length separator reads the input a paragraph at a time (two successive newlines in the input separate paragraphs). The stream must be opened for reading or an IOError
will be raised. The line read in will be returned and also assigned to $_
. Returns nil
if called at end of file. If the first argument is an integer, or optional second argument is given, the returning string would not be longer than the given value in bytes.
File.new("testfile").gets #=> "This is line one\n" $_ #=> "This is line one\n" File.new("testfile").gets(4)#=> "This"
If IO
contains multibyte characters byte then gets(1)
returns character entirely:
# Russian characters take 2 bytes File.write("testfile", "\u{442 435 441 442}") File.open("testfile") {|f|f.gets(1)} #=> "\u0442" File.open("testfile") {|f|f.gets(2)} #=> "\u0442" File.open("testfile") {|f|f.gets(3)} #=> "\u0442\u0435" File.open("testfile") {|f|f.gets(4)} #=> "\u0442\u0435"
static VALUE rb_io_gets_m(int argc, VALUE *argv, VALUE io) { VALUE str; str = rb_io_getline(argc, argv, io); rb_lastline_set(str); return str; }
static VALUE console_goto(VALUE io, VALUE x, VALUE y) { rb_io_t *fptr; int fd; COORD pos; GetOpenFile(io, fptr); fd = GetWriteFD(fptr); pos.X = NUM2UINT(x); pos.Y = NUM2UINT(y); if (!SetConsoleCursorPosition((HANDLE)rb_w32_get_osfhandle(fd), pos)) { rb_syserr_fail(LAST_ERROR, 0); } return io; }
Flushes input buffer in kernel.
You must require 'io/console' to use this method.
static VALUE console_iflush(VALUE io) { rb_io_t *fptr; int fd; GetOpenFile(io, fptr); fd = GetReadFD(fptr); #if defined HAVE_TERMIOS_H || defined HAVE_TERMIO_H if (tcflush(fd, TCIFLUSH)) rb_sys_fail(0); #endif (void)fd; return io; }
Return a string describing this IO
object.
static VALUE rb_io_inspect(VALUE obj) { rb_io_t *fptr; VALUE result; static const char closed[] = " (closed)"; fptr = RFILE(obj)->fptr; if (!fptr) return rb_any_to_s(obj); result = rb_str_new_cstr("#<"); rb_str_append(result, rb_class_name(CLASS_OF(obj))); rb_str_cat2(result, ":"); if (NIL_P(fptr->pathv)) { if (fptr->fd < 0) { rb_str_cat(result, closed+1, strlen(closed)-1); } else { rb_str_catf(result, "fd %d", fptr->fd); } } else { rb_str_append(result, fptr->pathv); if (fptr->fd < 0) { rb_str_cat(result, closed, strlen(closed)); } } return rb_str_cat2(result, ">"); }
Returns the Encoding
of the internal string if conversion is specified. Otherwise returns nil
.
static VALUE rb_io_internal_encoding(VALUE io) { rb_io_t *fptr; GetOpenFile(io, fptr); if (!fptr->encs.enc2) return Qnil; return rb_enc_from_encoding(io_read_encoding(fptr)); }
Provides a mechanism for issuing low-level commands to control or query I/O devices. Arguments and results are platform dependent. If arg is a number, its value is passed directly. If it is a string, it is interpreted as a binary sequence of bytes. On Unix platforms, see ioctl(2)
for details. Not implemented on all platforms.
static VALUE rb_io_ioctl(int argc, VALUE *argv, VALUE io) { VALUE req, arg; rb_scan_args(argc, argv, "11", &req, &arg); return rb_ioctl(io, req, arg); }
Flushes input and output buffers in kernel.
You must require 'io/console' to use this method.
static VALUE console_ioflush(VALUE io) { rb_io_t *fptr; #if defined HAVE_TERMIOS_H || defined HAVE_TERMIO_H int fd1, fd2; #endif GetOpenFile(io, fptr); #if defined HAVE_TERMIOS_H || defined HAVE_TERMIO_H fd1 = GetReadFD(fptr); fd2 = GetWriteFD(fptr); if (fd2 != -1 && fd1 != fd2) { if (tcflush(fd1, TCIFLUSH)) rb_sys_fail(0); if (tcflush(fd2, TCOFLUSH)) rb_sys_fail(0); } else { if (tcflush(fd1, TCIOFLUSH)) rb_sys_fail(0); } #endif return io; }
Returns true
if ios is associated with a terminal device (tty), false
otherwise.
File.new("testfile").isatty #=> false File.new("/dev/tty").isatty #=> true
static VALUE rb_io_isatty(VALUE io) { rb_io_t *fptr; GetOpenFile(io, fptr); if (isatty(fptr->fd) == 0) return Qfalse; return Qtrue; }
Returns the current line number in ios. The stream must be opened for reading. lineno
counts the number of times gets
is called rather than the number of newlines encountered. The two values will differ if gets
is called with a separator other than newline.
Methods that use $/
like each
, lines
and readline
will also increment lineno
.
See also the $.
variable.
f = File.new("testfile") f.lineno #=> 0 f.gets #=> "This is line one\n" f.lineno #=> 1 f.gets #=> "This is line two\n" f.lineno #=> 2
static VALUE rb_io_lineno(VALUE io) { rb_io_t *fptr; GetOpenFile(io, fptr); rb_io_check_char_readable(fptr); return INT2NUM(fptr->lineno); }
Manually sets the current line number to the given value. $.
is updated only on the next read.
f = File.new("testfile") f.gets #=> "This is line one\n" $. #=> 1 f.lineno = 1000 f.lineno #=> 1000 $. #=> 1 # lineno of last read f.gets #=> "This is line two\n" $. #=> 1001 # lineno of last read
static VALUE rb_io_set_lineno(VALUE io, VALUE lineno) { rb_io_t *fptr; GetOpenFile(io, fptr); rb_io_check_char_readable(fptr); fptr->lineno = NUM2INT(lineno); return lineno; }
This is a deprecated alias for each_line
.
static VALUE rb_io_lines(int argc, VALUE *argv, VALUE io) { rb_warn("IO#lines is deprecated; use #each_line instead"); if (!rb_block_given_p()) return rb_enumeratorize(io, ID2SYM(rb_intern("each_line")), argc, argv); return rb_io_each_line(argc, argv, io); }
Yields self
with disabling echo back.
STDIN.noecho(&:gets)
will read and return a line without echo back.
You must require 'io/console' to use this method.
static VALUE console_noecho(VALUE io) { return ttymode(io, rb_yield, set_noecho, NULL); }
Yields self
in non-blocking mode.
When false
is given as an argument, self
is yielded in blocking mode. The original mode is restored after the block is executed.
static VALUE rb_io_nonblock_block(int argc, VALUE *argv, VALUE io) { int nb = 1; rb_io_t *fptr; int f, restore[2]; GetOpenFile(io, fptr); if (argc > 0) { VALUE v; rb_scan_args(argc, argv, "01", &v); nb = RTEST(v); } f = io_nonblock_mode(fptr->fd); restore[0] = fptr->fd; restore[1] = f; if (!io_nonblock_set(fptr->fd, f, nb)) return rb_yield(io); return rb_ensure(rb_yield, io, io_nonblock_restore, (VALUE)restore); }
Enables non-blocking mode on a stream when set to true
, and blocking mode when set to false
.
static VALUE rb_io_nonblock_set(VALUE io, VALUE nb) { rb_io_t *fptr; GetOpenFile(io, fptr); if (RTEST(nb)) rb_io_set_nonblock(fptr); else io_nonblock_set(fptr->fd, io_nonblock_mode(fptr->fd), RTEST(nb)); return io; }
Returns true
if an IO
object is in non-blocking mode.
static VALUE rb_io_nonblock_p(VALUE io) { rb_io_t *fptr; GetOpenFile(io, fptr); if (io_nonblock_mode(fptr->fd) & O_NONBLOCK) return Qtrue; return Qfalse; }
Returns number of bytes that can be read without blocking. Returns zero if no information available.
static VALUE io_nread(VALUE io) { rb_io_t *fptr; int len; ioctl_arg n; GetOpenFile(io, fptr); rb_io_check_readable(fptr); len = rb_io_read_pending(fptr); if (len > 0) return INT2FIX(len); if (!FIONREAD_POSSIBLE_P(fptr->fd)) return INT2FIX(0); if (ioctl(fptr->fd, FIONREAD, &n)) return INT2FIX(0); if (n > 0) return ioctl_arg2num(n); return INT2FIX(0); }
Flushes output buffer in kernel.
You must require 'io/console' to use this method.
static VALUE console_oflush(VALUE io) { rb_io_t *fptr; int fd; GetOpenFile(io, fptr); fd = GetWriteFD(fptr); #if defined HAVE_TERMIOS_H || defined HAVE_TERMIO_H if (tcflush(fd, TCOFLUSH)) rb_sys_fail(0); #endif (void)fd; return io; }
Returns pathname configuration variable using fpathconf().
name should be a constant under Etc
which begins with PC_
.
The return value is an integer or nil. nil means indefinite limit. (fpathconf() returns -1 but errno is not set.)
require 'etc' IO.pipe {|r, w| p w.pathconf(Etc::PC_PIPE_BUF) #=> 4096 }
static VALUE io_pathconf(VALUE io, VALUE arg) { int name; long ret; rb_io_t *fptr; name = NUM2INT(arg); GetOpenFile(io, fptr); errno = 0; ret = fpathconf(fptr->fd, name); if (ret == -1) { if (errno == 0) /* no limit */ return Qnil; rb_sys_fail("fpathconf"); } return LONG2NUM(ret); }
Returns the process ID of a child process associated with ios. This will be set by IO.popen
.
pipe = IO.popen("-") if pipe $stderr.puts "In parent, child pid is #{pipe.pid}" else $stderr.puts "In child, pid is #{$$}" end
produces:
In child, pid is 26209 In parent, child pid is 26209
static VALUE rb_io_pid(VALUE io) { rb_io_t *fptr; GetOpenFile(io, fptr); if (!fptr->pid) return Qnil; return PIDT2NUM(fptr->pid); }
Returns the current offset (in bytes) of ios.
f = File.new("testfile") f.pos #=> 0 f.gets #=> "This is line one\n" f.pos #=> 17
static VALUE rb_io_tell(VALUE io) { rb_io_t *fptr; off_t pos; GetOpenFile(io, fptr); pos = io_tell(fptr); if (pos < 0 && errno) rb_sys_fail_path(fptr->pathv); pos -= fptr->rbuf.len; return OFFT2NUM(pos); }
Seeks to the given position (in bytes) in ios. It is not guaranteed that seeking to the right position when ios is textmode.
f = File.new("testfile") f.pos = 17 f.gets #=> "This is line two\n"
static VALUE rb_io_set_pos(VALUE io, VALUE offset) { rb_io_t *fptr; off_t pos; pos = NUM2OFFT(offset); GetOpenFile(io, fptr); pos = io_seek(fptr, pos, SEEK_SET); if (pos < 0 && errno) rb_sys_fail_path(fptr->pathv); return OFFT2NUM(pos); }
static VALUE console_key_pressed_p(VALUE io, VALUE k) { int vk = -1; if (FIXNUM_P(k)) { vk = NUM2UINT(k); } else { const struct vktable *t; if (SYMBOL_P(k)) { k = rb_sym2str(k); } else { StringValueCStr(k); } t = console_win32_vk(RSTRING_PTR(k), RSTRING_LEN(k)); if (!t || (vk = (short)t->vk) == -1) { rb_raise(rb_eArgError, "unknown virtual key code: %"PRIsVALUE, k); } } return GetKeyState(vk) & 0x80 ? Qtrue : Qfalse; }
Writes the given object(s) to ios. Returns nil
.
The stream must be opened for writing. Each given object that isn't a string will be converted by calling its to_s
method. When called without arguments, prints the contents of $_
.
If the output field separator ($,
) is not nil
, it is inserted between objects. If the output record separator ($\
) is not nil
, it is appended to the output.
$stdout.print("This is ", 100, " percent.\n")
produces:
This is 100 percent.
VALUE rb_io_print(int argc, const VALUE *argv, VALUE out) { int i; VALUE line; /* if no argument given, print `$_' */ if (argc == 0) { argc = 1; line = rb_lastline_get(); argv = &line; } for (i=0; i<argc; i++) { if (!NIL_P(rb_output_fs) && i>0) { rb_io_write(out, rb_output_fs); } rb_io_write(out, argv[i]); } if (argc > 0 && !NIL_P(rb_output_rs)) { rb_io_write(out, rb_output_rs); } return Qnil; }
Formats and writes to ios, converting parameters under control of the format string. See Kernel#sprintf
for details.
VALUE rb_io_printf(int argc, const VALUE *argv, VALUE out) { rb_io_write(out, rb_f_sprintf(argc, argv)); return Qnil; }
If obj is Numeric
, write the character whose code is the least-significant byte of obj, otherwise write the first byte of the string representation of obj to ios. Note: This method is not safe for use with multi-byte characters as it will truncate them.
$stdout.putc "A" $stdout.putc 65
produces:
AA
static VALUE rb_io_putc(VALUE io, VALUE ch) { VALUE str; if (RB_TYPE_P(ch, T_STRING)) { str = rb_str_substr(ch, 0, 1); } else { char c = NUM2CHR(ch); str = rb_str_new(&c, 1); } rb_io_write(io, str); return ch; }
Writes the given object(s) to ios. Writes a newline after any that do not already end with a newline sequence. Returns nil
.
The stream must be opened for writing. If called with an array argument, writes each element on a new line. Each given object that isn't a string or array will be converted by calling its to_s
method. If called without arguments, outputs a single newline.
$stdout.puts("this", "is", ["a", "test"])
produces:
this is a test
Note that puts
always uses newlines and is not affected by the output record separator ($\
).
VALUE rb_io_puts(int argc, const VALUE *argv, VALUE out) { int i; VALUE line; /* if no argument given, print newline. */ if (argc == 0) { rb_io_write(out, rb_default_rs); return Qnil; } for (i=0; i<argc; i++) { if (RB_TYPE_P(argv[i], T_STRING)) { line = argv[i]; goto string; } if (rb_exec_recursive(io_puts_ary, argv[i], out)) { continue; } line = rb_obj_as_string(argv[i]); string: rb_io_write(out, line); if (RSTRING_LEN(line) == 0 || !str_end_with_asciichar(line, '\n')) { rb_io_write(out, rb_default_rs); } } return Qnil; }
Yields self
within raw mode.
STDIN.raw(&:gets)
will read and return a line without echo back and line editing.
You must require 'io/console' to use this method.
static VALUE console_raw(int argc, VALUE *argv, VALUE io) { rawmode_arg_t opts, *optp = rawmode_opt(argc, argv, &opts); return ttymode(io, rb_yield, set_rawmode, optp); }
Enables raw mode.
If the terminal mode needs to be back, use io.raw { … }.
You must require 'io/console' to use this method.
static VALUE console_set_raw(int argc, VALUE *argv, VALUE io) { conmode t; rb_io_t *fptr; int fd; rawmode_arg_t opts, *optp = rawmode_opt(argc, argv, &opts); GetOpenFile(io, fptr); fd = GetReadFD(fptr); if (!getattr(fd, &t)) rb_sys_fail(0); set_rawmode(&t, optp); if (!setattr(fd, &t)) rb_sys_fail(0); return io; }
Reads length bytes from the I/O stream.
length must be a non-negative integer or nil
.
If length is a positive integer, read
tries to read length bytes without any conversion (binary mode). It returns nil
if an EOF is encountered before anything can be read. Fewer than length bytes are returned if an EOF is encountered during the read. In the case of an integer length, the resulting string is always in ASCII-8BIT encoding.
If length is omitted or is nil
, it reads until EOF and the encoding conversion is applied, if applicable. A string is returned even if EOF is encountered before any data is read.
If length is zero, it returns an empty string (""
).
If the optional outbuf argument is present, it must reference a String, which will receive the data. The outbuf will contain only the received data after the method call even if it is not empty at the beginning.
When this method is called at end of file, it returns nil
or ""
, depending on length: read
, read(nil)
, and read(0)
return ""
, read(positive_integer)
returns nil
.
f = File.new("testfile") f.read(16) #=> "This is line one" # read whole file open("file") do |f| data = f.read # This returns a string even if the file is empty. # ... end # iterate over fixed length records open("fixed-record-file") do |f| while record = f.read(256) # ... end end # iterate over variable length records, # each record is prefixed by its 32-bit length open("variable-record-file") do |f| while len = f.read(4) len = len.unpack("N")[0] # 32-bit length record = f.read(len) # This returns a string even if len is 0. end end
Note that this method behaves like the fread() function in C. This means it retries to invoke read(2) system calls to read data with the specified length (or until EOF). This behavior is preserved even if ios is in non-blocking mode. (This method is non-blocking flag insensitive as other methods.) If you need the behavior like a single read(2) system call, consider readpartial
, read_nonblock
, and sysread
.
static VALUE io_read(int argc, VALUE *argv, VALUE io) { rb_io_t *fptr; long n, len; VALUE length, str; #if defined(RUBY_TEST_CRLF_ENVIRONMENT) || defined(_WIN32) int previous_mode; #endif rb_scan_args(argc, argv, "02", &length, &str); if (NIL_P(length)) { GetOpenFile(io, fptr); rb_io_check_char_readable(fptr); return read_all(fptr, remain_size(fptr), str); } len = NUM2LONG(length); if (len < 0) { rb_raise(rb_eArgError, "negative length %ld given", len); } io_setstrbuf(&str,len); GetOpenFile(io, fptr); rb_io_check_byte_readable(fptr); if (len == 0) { io_set_read_length(str, 0); return str; } READ_CHECK(fptr); #if defined(RUBY_TEST_CRLF_ENVIRONMENT) || defined(_WIN32) previous_mode = set_binary_mode_with_seek_cur(fptr); #endif n = io_fread(str, 0, len, fptr); io_set_read_length(str, n); #if defined(RUBY_TEST_CRLF_ENVIRONMENT) || defined(_WIN32) if (previous_mode == O_TEXT) { setmode(fptr->fd, O_TEXT); } #endif if (n == 0) return Qnil; OBJ_TAINT(str); return str; }
Reads at most maxlen bytes from ios using the read(2) system call after O_NONBLOCK is set for the underlying file descriptor.
If the optional outbuf argument is present, it must reference a String, which will receive the data. The outbuf will contain only the received data after the method call even if it is not empty at the beginning.
read_nonblock
just calls the read(2) system call. It causes all errors the read(2) system call causes: Errno::EWOULDBLOCK, Errno::EINTR, etc. The caller should care such errors.
If the exception is Errno::EWOULDBLOCK or Errno::EAGAIN, it is extended by IO::WaitReadable
. So IO::WaitReadable
can be used to rescue the exceptions for retrying read_nonblock.
read_nonblock
causes EOFError
on EOF.
If the read byte buffer is not empty, read_nonblock
reads from the buffer like readpartial. In this case, the read(2) system call is not called.
When read_nonblock
raises an exception kind of IO::WaitReadable
, read_nonblock
should not be called until io is readable for avoiding busy loop. This can be done as follows.
# emulates blocking read (readpartial). begin result = io.read_nonblock(maxlen) rescue IO::WaitReadable IO.select([io]) retry end
Although IO#read_nonblock
doesn't raise IO::WaitWritable
. OpenSSL::Buffering#read_nonblock
can raise IO::WaitWritable
. If IO
and SSL should be used polymorphically, IO::WaitWritable
should be rescued too. See the document of OpenSSL::Buffering#read_nonblock
for sample code.
Note that this method is identical to readpartial except the non-blocking flag is set.
By specifying `exception: false`, the options hash allows you to indicate that read_nonblock
should not raise an IO::WaitReadable
exception, but return the symbol :wait_readable instead.
# File prelude.rb, line 73 def read_nonblock(len, buf = nil, exception: true) __read_nonblock(len, buf, exception) end
Reads a byte as with IO#getbyte
, but raises an EOFError
on end of file.
static VALUE rb_io_readbyte(VALUE io) { VALUE c = rb_io_getbyte(io); if (NIL_P(c)) { rb_eof_error(); } return c; }
Reads a one-character string from ios. Raises an EOFError
on end of file.
f = File.new("testfile") f.readchar #=> "h" f.readchar #=> "e"
static VALUE rb_io_readchar(VALUE io) { VALUE c = rb_io_getc(io); if (NIL_P(c)) { rb_eof_error(); } return c; }
Reads a line as with IO#gets
, but raises an EOFError
on end of file.
static VALUE rb_io_readline(int argc, VALUE *argv, VALUE io) { VALUE line = rb_io_gets_m(argc, argv, io); if (NIL_P(line)) { rb_eof_error(); } return line; }
Reads all of the lines in ios, and returns them in anArray. Lines are separated by the optional sep. If sep is nil
, the rest of the stream is returned as a single record. If the first argument is an integer, or optional second argument is given, the returning string would not be longer than the given value in bytes. The stream must be opened for reading or an IOError
will be raised.
f = File.new("testfile") f.readlines[0] #=> "This is line one\n"
static VALUE rb_io_readlines(int argc, VALUE *argv, VALUE io) { VALUE line, ary, rs; long limit; prepare_getline_args(argc, argv, &rs, &limit, io); if (limit == 0) rb_raise(rb_eArgError, "invalid limit: 0 for readlines"); ary = rb_ary_new(); while (!NIL_P(line = rb_io_getline_1(rs, limit, io))) { rb_ary_push(ary, line); } return ary; }
Reads at most maxlen bytes from the I/O stream. It blocks only if ios has no data immediately available. It doesn't block if some data available.
If the optional outbuf argument is present, it must reference a String, which will receive the data. The outbuf will contain only the received data after the method call even if it is not empty at the beginning.
It raises EOFError
on end of file.
readpartial is designed for streams such as pipe, socket, tty, etc. It blocks only when no data immediately available. This means that it blocks only when following all conditions hold.
-
the byte buffer in the
IO
object is empty. -
the content of the stream is empty.
-
the stream is not reached to EOF.
When readpartial blocks, it waits data or EOF on the stream. If some data is reached, readpartial returns with the data. If EOF is reached, readpartial raises EOFError
.
When readpartial doesn't blocks, it returns or raises immediately. If the byte buffer is not empty, it returns the data in the buffer. Otherwise if the stream has some content, it returns the data in the stream. Otherwise if the stream is reached to EOF, it raises EOFError
.
r, w = IO.pipe # buffer pipe content w << "abc" # "" "abc". r.readpartial(4096) #=> "abc" "" "" r.readpartial(4096) # blocks because buffer and pipe is empty. r, w = IO.pipe # buffer pipe content w << "abc" # "" "abc" w.close # "" "abc" EOF r.readpartial(4096) #=> "abc" "" EOF r.readpartial(4096) # raises EOFError r, w = IO.pipe # buffer pipe content w << "abc\ndef\n" # "" "abc\ndef\n" r.gets #=> "abc\n" "def\n" "" w << "ghi\n" # "def\n" "ghi\n" r.readpartial(4096) #=> "def\n" "" "ghi\n" r.readpartial(4096) #=> "ghi\n" "" ""
Note that readpartial behaves similar to sysread. The differences are:
-
If the byte buffer is not empty, read from the byte buffer instead of “sysread for buffered
IO
(IOError)”. -
It doesn't cause Errno::EWOULDBLOCK and Errno::EINTR. When readpartial meets EWOULDBLOCK and EINTR by read system call, readpartial retry the system call.
The latter means that readpartial is nonblocking-flag insensitive. It blocks on the situation IO#sysread
causes Errno::EWOULDBLOCK as if the fd is blocking mode.
static VALUE io_readpartial(int argc, VALUE *argv, VALUE io) { VALUE ret; ret = io_getpartial(argc, argv, io, Qnil, 0); if (NIL_P(ret)) rb_eof_error(); return ret; }
Returns true if input available without blocking, or false. Returns nil if no information available.
static VALUE io_ready_p(VALUE io) { rb_io_t *fptr; struct timeval tv = {0, 0}; GetOpenFile(io, fptr); rb_io_check_readable(fptr); if (rb_io_read_pending(fptr)) return Qtrue; if (wait_for_single_fd(fptr, RB_WAITFD_IN, &tv)) return Qtrue; return Qfalse; }
Reassociates ios with the I/O stream given in other_IO or to a new stream opened on path. This may dynamically change the actual class of this stream.
f1 = File.new("testfile") f2 = File.new("testfile") f2.readlines[0] #=> "This is line one\n" f2.reopen(f1) #=> #<File:testfile> f2.readlines[0] #=> "This is line one\n"
static VALUE rb_io_reopen(int argc, VALUE *argv, VALUE file) { VALUE fname, nmode, opt; int oflags; rb_io_t *fptr; if (rb_scan_args(argc, argv, "11:", &fname, &nmode, &opt) == 1) { VALUE tmp = rb_io_check_io(fname); if (!NIL_P(tmp)) { return io_reopen(file, tmp); } } FilePathValue(fname); rb_io_taint_check(file); fptr = RFILE(file)->fptr; if (!fptr) { fptr = RFILE(file)->fptr = ZALLOC(rb_io_t); } if (!NIL_P(nmode) || !NIL_P(opt)) { int fmode; convconfig_t convconfig; rb_io_extract_modeenc(&nmode, 0, opt, &oflags, &fmode, &convconfig); if (IS_PREP_STDIO(fptr) && ((fptr->mode & FMODE_READWRITE) & (fmode & FMODE_READWRITE)) != (fptr->mode & FMODE_READWRITE)) { rb_raise(rb_eArgError, "%s can't change access mode from \"%s\" to \"%s\"", PREP_STDIO_NAME(fptr), rb_io_fmode_modestr(fptr->mode), rb_io_fmode_modestr(fmode)); } fptr->mode = fmode; fptr->encs = convconfig; } else { oflags = rb_io_fmode_oflags(fptr->mode); } fptr->pathv = fname; if (fptr->fd < 0) { fptr->fd = rb_sysopen(fptr->pathv, oflags, 0666); fptr->stdio_file = 0; return file; } if (fptr->mode & FMODE_WRITABLE) { if (io_fflush(fptr) < 0) rb_sys_fail(0); } fptr->rbuf.off = fptr->rbuf.len = 0; if (fptr->stdio_file) { int e = rb_freopen(rb_str_encode_ospath(fptr->pathv), rb_io_oflags_modestr(oflags), fptr->stdio_file); if (e) rb_syserr_fail_path(e, fptr->pathv); fptr->fd = fileno(fptr->stdio_file); rb_fd_fix_cloexec(fptr->fd); #ifdef USE_SETVBUF if (setvbuf(fptr->stdio_file, NULL, _IOFBF, 0) != 0) rb_warn("setvbuf() can't be honoured for %"PRIsVALUE, fptr->pathv); #endif if (fptr->stdio_file == stderr) { if (setvbuf(fptr->stdio_file, NULL, _IONBF, BUFSIZ) != 0) rb_warn("setvbuf() can't be honoured for %"PRIsVALUE, fptr->pathv); } else if (fptr->stdio_file == stdout && isatty(fptr->fd)) { if (setvbuf(fptr->stdio_file, NULL, _IOLBF, BUFSIZ) != 0) rb_warn("setvbuf() can't be honoured for %"PRIsVALUE, fptr->pathv); } } else { int tmpfd = rb_sysopen(fptr->pathv, oflags, 0666); int err = 0; if (rb_cloexec_dup2(tmpfd, fptr->fd) < 0) err = errno; (void)close(tmpfd); if (err) { rb_syserr_fail_path(err, fptr->pathv); } } return file; }
Positions ios to the beginning of input, resetting lineno
to zero.
f = File.new("testfile") f.readline #=> "This is line one\n" f.rewind #=> 0 f.lineno #=> 0 f.readline #=> "This is line one\n"
Note that it cannot be used with streams such as pipes, ttys, and sockets.
static VALUE rb_io_rewind(VALUE io) { rb_io_t *fptr; GetOpenFile(io, fptr); if (io_seek(fptr, 0L, 0) < 0 && errno) rb_sys_fail_path(fptr->pathv); if (io == ARGF.current_file) { ARGF.lineno -= fptr->lineno; } fptr->lineno = 0; if (fptr->readconv) { clear_readconv(fptr); } return INT2FIX(0); }
Scans the current string until the match is exhausted, yielding each match as it is encountered in the string. A block is not necessary though, as the results will simply be aggregated into the final array.
"123 456".block_scanf("%d") # => [123, 456]
If a block is given, the value from that is returned from the yield is added to an output array.
"123 456".block_scanf("%d") do |digit,| # the ',' unpacks the Array digit + 100 end # => [223, 556]
See Scanf
for details on creating a format string.
You will need to require 'scanf' to use IO#scanf
.
# File lib/scanf.rb, line 614 def scanf(str,&b) #:yield: current_match return block_scanf(str,&b) if b return [] unless str.size > 0 start_position = pos rescue 0 matched_so_far = 0 source_buffer = "" result_buffer = [] final_result = [] fstr = Scanf::FormatString.new(str) loop do if eof || (tty? &&! fstr.match(source_buffer)) final_result.concat(result_buffer) break end source_buffer << gets current_match = fstr.match(source_buffer) spec = fstr.last_spec_tried if spec.matched if spec.mid_match? result_buffer.replace(current_match) next end elsif (fstr.matched_count == fstr.spec_count - 1) if /\A\s*\z/.match(fstr.string_left) break if spec.count_space? result_buffer.replace(current_match) next end end final_result.concat(current_match) matched_so_far += source_buffer.size source_buffer.replace(fstr.string_left) matched_so_far -= source_buffer.size break if fstr.last_spec fstr.prune end begin seek(start_position + matched_so_far, IO::SEEK_SET) rescue Errno::ESPIPE end soak_up_spaces if fstr.last_spec && fstr.space return final_result end
Seeks to a given offset anInteger in the stream according to the value of whence:
:CUR or IO::SEEK_CUR | Seeks to _amount_ plus current position ----------------------+-------------------------------------------------- :END or IO::SEEK_END | Seeks to _amount_ plus end of stream (you | probably want a negative value for _amount_) ----------------------+-------------------------------------------------- :SET or IO::SEEK_SET | Seeks to the absolute location given by _amount_
Example:
f = File.new("testfile") f.seek(-13, IO::SEEK_END) #=> 0 f.readline #=> "And so on...\n"
static VALUE rb_io_seek_m(int argc, VALUE *argv, VALUE io) { VALUE offset, ptrname; int whence = SEEK_SET; if (rb_scan_args(argc, argv, "11", &offset, &ptrname) == 2) { whence = interpret_seek_whence(ptrname); } return rb_io_seek(io, offset, whence); }
If single argument is specified, read string from io is tagged with the encoding specified. If encoding is a colon separated two encoding names “A:B”, the read string is converted from encoding A (external encoding) to encoding B (internal encoding), then tagged with B. If two arguments are specified, those must be encoding objects or encoding names, and the first one is the external encoding, and the second one is the internal encoding. If the external encoding and the internal encoding is specified, optional hash argument specify the conversion option.
static VALUE rb_io_set_encoding(int argc, VALUE *argv, VALUE io) { rb_io_t *fptr; VALUE v1, v2, opt; if (!RB_TYPE_P(io, T_FILE)) { return rb_funcall2(io, id_set_encoding, argc, argv); } argc = rb_scan_args(argc, argv, "11:", &v1, &v2, &opt); GetOpenFile(io, fptr); io_encoding_set(fptr, v1, v2, opt); return io; }
Returns status information for ios as an object of type File::Stat
.
f = File.new("testfile") s = f.stat "%o" % s.mode #=> "100644" s.blksize #=> 4096 s.atime #=> Wed Apr 09 08:53:54 CDT 2003
static VALUE rb_io_stat(VALUE obj) { rb_io_t *fptr; struct stat st; GetOpenFile(obj, fptr); if (fstat(fptr->fd, &st) == -1) { rb_sys_fail_path(fptr->pathv); } return rb_stat_new(&st); }
Returns the current “sync mode'' of ios. When sync mode is true, all output is immediately flushed to the underlying operating system and is not buffered by Ruby internally. See also IO#fsync
.
f = File.new("testfile") f.sync #=> false
static VALUE rb_io_sync(VALUE io) { rb_io_t *fptr; io = GetWriteIO(io); GetOpenFile(io, fptr); return (fptr->mode & FMODE_SYNC) ? Qtrue : Qfalse; }
Sets the “sync mode'' to true
or false
. When sync mode is true, all output is immediately flushed to the underlying operating system and is not buffered internally. Returns the new state. See also IO#fsync
.
f = File.new("testfile") f.sync = true
(produces no output)
static VALUE rb_io_set_sync(VALUE io, VALUE sync) { rb_io_t *fptr; io = GetWriteIO(io); GetOpenFile(io, fptr); if (RTEST(sync)) { fptr->mode |= FMODE_SYNC; } else { fptr->mode &= ~FMODE_SYNC; } return sync; }
Reads maxlen bytes from ios using a low-level read and returns them as a string. Do not mix with other methods that read from ios or you may get unpredictable results.
If the optional outbuf argument is present, it must reference a String, which will receive the data. The outbuf will contain only the received data after the method call even if it is not empty at the beginning.
Raises SystemCallError
on error and EOFError
at end of file.
f = File.new("testfile") f.sysread(16) #=> "This is line one"
static VALUE rb_io_sysread(int argc, VALUE *argv, VALUE io) { VALUE len, str; rb_io_t *fptr; long n, ilen; struct read_internal_arg arg; rb_scan_args(argc, argv, "11", &len, &str); ilen = NUM2LONG(len); io_setstrbuf(&str,ilen); if (ilen == 0) return str; GetOpenFile(io, fptr); rb_io_check_byte_readable(fptr); if (READ_DATA_BUFFERED(fptr)) { rb_raise(rb_eIOError, "sysread for buffered IO"); } /* * FIXME: removing rb_thread_wait_fd() here changes sysread semantics * on non-blocking IOs. However, it's still currently possible * for sysread to raise Errno::EAGAIN if another thread read()s * the IO after we return from rb_thread_wait_fd() but before * we call read() */ rb_thread_wait_fd(fptr->fd); rb_io_check_closed(fptr); io_setstrbuf(&str, ilen); rb_str_locktmp(str); arg.fd = fptr->fd; arg.str_ptr = RSTRING_PTR(str); arg.len = ilen; rb_ensure(read_internal_call, (VALUE)&arg, rb_str_unlocktmp, str); n = arg.len; if (n == -1) { rb_sys_fail_path(fptr->pathv); } io_set_read_length(str, n); if (n == 0 && ilen > 0) { rb_eof_error(); } OBJ_TAINT(str); return str; }
Seeks to a given offset in the stream according to the value of whence (see IO#seek
for values of whence). Returns the new offset into the file.
f = File.new("testfile") f.sysseek(-13, IO::SEEK_END) #=> 53 f.sysread(10) #=> "And so on."
static VALUE rb_io_sysseek(int argc, VALUE *argv, VALUE io) { VALUE offset, ptrname; int whence = SEEK_SET; rb_io_t *fptr; off_t pos; if (rb_scan_args(argc, argv, "11", &offset, &ptrname) == 2) { whence = interpret_seek_whence(ptrname); } pos = NUM2OFFT(offset); GetOpenFile(io, fptr); if ((fptr->mode & FMODE_READABLE) && (READ_DATA_BUFFERED(fptr) || READ_CHAR_PENDING(fptr))) { rb_raise(rb_eIOError, "sysseek for buffered IO"); } if ((fptr->mode & FMODE_WRITABLE) && fptr->wbuf.len) { rb_warn("sysseek for buffered IO"); } errno = 0; pos = lseek(fptr->fd, pos, whence); if (pos == -1 && errno) rb_sys_fail_path(fptr->pathv); return OFFT2NUM(pos); }
Writes the given string to ios using a low-level write. Returns the number of bytes written. Do not mix with other methods that write to ios or you may get unpredictable results. Raises SystemCallError
on error.
f = File.new("out", "w") f.syswrite("ABCDEF") #=> 6
static VALUE rb_io_syswrite(VALUE io, VALUE str) { rb_io_t *fptr; long n; if (!RB_TYPE_P(str, T_STRING)) str = rb_obj_as_string(str); io = GetWriteIO(io); GetOpenFile(io, fptr); rb_io_check_writable(fptr); str = rb_str_new_frozen(str); if (fptr->wbuf.len) { rb_warn("syswrite for buffered IO"); } n = rb_write_internal(fptr->fd, RSTRING_PTR(str), RSTRING_LEN(str)); RB_GC_GUARD(str); if (n == -1) rb_sys_fail_path(fptr->pathv); return LONG2FIX(n); }
Returns the current offset (in bytes) of ios.
f = File.new("testfile") f.pos #=> 0 f.gets #=> "This is line one\n" f.pos #=> 17
static VALUE rb_io_tell(VALUE io) { rb_io_t *fptr; off_t pos; GetOpenFile(io, fptr); pos = io_tell(fptr); if (pos < 0 && errno) rb_sys_fail_path(fptr->pathv); pos -= fptr->rbuf.len; return OFFT2NUM(pos); }
Returns ios.
static VALUE rb_io_to_io(VALUE io) { return io; }
Returns true
if ios is associated with a terminal device (tty), false
otherwise.
File.new("testfile").isatty #=> false File.new("/dev/tty").isatty #=> true
static VALUE rb_io_isatty(VALUE io) { rb_io_t *fptr; GetOpenFile(io, fptr); if (isatty(fptr->fd) == 0) return Qfalse; return Qtrue; }
Pushes back bytes (passed as a parameter) onto ios, such that a subsequent buffered read will return it. Only one byte may be pushed back before a subsequent read operation (that is, you will be able to read only the last of several bytes that have been pushed back). Has no effect with unbuffered reads (such as IO#sysread
).
f = File.new("testfile") #=> #<File:testfile> b = f.getbyte #=> 0x38 f.ungetbyte(b) #=> nil f.getbyte #=> 0x38
VALUE rb_io_ungetbyte(VALUE io, VALUE b) { rb_io_t *fptr; GetOpenFile(io, fptr); rb_io_check_byte_readable(fptr); if (NIL_P(b)) return Qnil; if (FIXNUM_P(b)) { char cc = FIX2INT(b); b = rb_str_new(&cc, 1); } else { SafeStringValue(b); } io_ungetbyte(b, fptr); return Qnil; }
Pushes back one character (passed as a parameter) onto ios, such that a subsequent buffered character read will return it. Only one character may be pushed back before a subsequent read operation (that is, you will be able to read only the last of several characters that have been pushed back). Has no effect with unbuffered reads (such as IO#sysread
).
f = File.new("testfile") #=> #<File:testfile> c = f.getc #=> "8" f.ungetc(c) #=> nil f.getc #=> "8"
VALUE rb_io_ungetc(VALUE io, VALUE c) { rb_io_t *fptr; long len; GetOpenFile(io, fptr); rb_io_check_char_readable(fptr); if (NIL_P(c)) return Qnil; if (FIXNUM_P(c)) { c = rb_enc_uint_chr(FIX2UINT(c), io_read_encoding(fptr)); } else if (RB_TYPE_P(c, T_BIGNUM)) { c = rb_enc_uint_chr(NUM2UINT(c), io_read_encoding(fptr)); } else { SafeStringValue(c); } if (NEED_READCONV(fptr)) { SET_BINARY_MODE(fptr); len = RSTRING_LEN(c); #if SIZEOF_LONG > SIZEOF_INT if (len > INT_MAX) rb_raise(rb_eIOError, "ungetc failed"); #endif make_readconv(fptr, (int)len); if (fptr->cbuf.capa - fptr->cbuf.len < len) rb_raise(rb_eIOError, "ungetc failed"); if (fptr->cbuf.off < len) { MEMMOVE(fptr->cbuf.ptr+fptr->cbuf.capa-fptr->cbuf.len, fptr->cbuf.ptr+fptr->cbuf.off, char, fptr->cbuf.len); fptr->cbuf.off = fptr->cbuf.capa-fptr->cbuf.len; } fptr->cbuf.off -= (int)len; fptr->cbuf.len += (int)len; MEMMOVE(fptr->cbuf.ptr+fptr->cbuf.off, RSTRING_PTR(c), char, len); } else { NEED_NEWLINE_DECORATOR_ON_READ_CHECK(fptr); io_ungetbyte(c, fptr); } return Qnil; }
Waits until IO
is readable without blocking and returns self
, or nil
when times out. Returns true
immediately when buffered data is available.
static VALUE io_wait_readable(int argc, VALUE *argv, VALUE io) { rb_io_t *fptr; struct timeval timerec; struct timeval *tv; GetOpenFile(io, fptr); rb_io_check_readable(fptr); tv = get_timeout(argc, argv, &timerec); if (rb_io_read_pending(fptr)) return Qtrue; if (wait_for_single_fd(fptr, RB_WAITFD_IN, tv)) { return io; } return Qnil; }
Waits until IO
is readable without blocking and returns self
, or nil
when times out. Returns true
immediately when buffered data is available.
static VALUE io_wait_readable(int argc, VALUE *argv, VALUE io) { rb_io_t *fptr; struct timeval timerec; struct timeval *tv; GetOpenFile(io, fptr); rb_io_check_readable(fptr); tv = get_timeout(argc, argv, &timerec); if (rb_io_read_pending(fptr)) return Qtrue; if (wait_for_single_fd(fptr, RB_WAITFD_IN, tv)) { return io; } return Qnil; }
Waits until IO
is writable without blocking and returns self
or nil
when times out.
static VALUE io_wait_writable(int argc, VALUE *argv, VALUE io) { rb_io_t *fptr; struct timeval timerec; struct timeval *tv; GetOpenFile(io, fptr); rb_io_check_writable(fptr); tv = get_timeout(argc, argv, &timerec); if (wait_for_single_fd(fptr, RB_WAITFD_OUT, tv)) { return io; } return Qnil; }
Returns console size.
You must require 'io/console' to use this method.
static VALUE console_winsize(VALUE io) { rb_io_t *fptr; int fd; rb_console_size_t ws; GetOpenFile(io, fptr); fd = GetWriteFD(fptr); if (!getwinsize(fd, &ws)) rb_sys_fail(0); return rb_assoc_new(INT2NUM(winsize_row(&ws)), INT2NUM(winsize_col(&ws))); }
Tries to set console size. The effect depends on the platform and the running environment.
You must require 'io/console' to use this method.
static VALUE console_set_winsize(VALUE io, VALUE size) { rb_io_t *fptr; rb_console_size_t ws; #if defined _WIN32 HANDLE wh; int newrow, newcol; #endif VALUE row, col, xpixel, ypixel; const VALUE *sz; int fd; long sizelen; GetOpenFile(io, fptr); size = rb_Array(size); if ((sizelen = RARRAY_LEN(size)) != 2 && sizelen != 4) { rb_raise(rb_eArgError, "wrong number of arguments (given %ld, expected 2 or 4)", sizelen); } sz = RARRAY_CONST_PTR(size); row = sz[0], col = sz[1], xpixel = ypixel = Qnil; if (sizelen == 4) xpixel = sz[2], ypixel = sz[3]; fd = GetWriteFD(fptr); #if defined TIOCSWINSZ ws.ws_row = ws.ws_col = ws.ws_xpixel = ws.ws_ypixel = 0; #define SET(m) ws.ws_##m = NIL_P(m) ? 0 : (unsigned short)NUM2UINT(m) SET(row); SET(col); SET(xpixel); SET(ypixel); #undef SET if (!setwinsize(fd, &ws)) rb_sys_fail(0); #elif defined _WIN32 wh = (HANDLE)rb_w32_get_osfhandle(fd); #define SET(m) new##m = NIL_P(m) ? 0 : (unsigned short)NUM2UINT(m) SET(row); SET(col); #undef SET if (!NIL_P(xpixel)) (void)NUM2UINT(xpixel); if (!NIL_P(ypixel)) (void)NUM2UINT(ypixel); if (!GetConsoleScreenBufferInfo(wh, &ws)) { rb_syserr_fail(LAST_ERROR, "GetConsoleScreenBufferInfo"); } if ((ws.dwSize.X < newcol && (ws.dwSize.X = newcol, 1)) || (ws.dwSize.Y < newrow && (ws.dwSize.Y = newrow, 1))) { if (!SetConsoleScreenBufferSize(wh, ws.dwSize)) { rb_syserr_fail(LAST_ERROR, "SetConsoleScreenBufferInfo"); } } ws.srWindow.Left = 0; ws.srWindow.Top = 0; ws.srWindow.Right = newcol; ws.srWindow.Bottom = newrow; if (!SetConsoleWindowInfo(wh, FALSE, &ws.srWindow)) { rb_syserr_fail(LAST_ERROR, "SetConsoleWindowInfo"); } #endif return io; }
Writes the given string to ios. The stream must be opened for writing. If the argument is not a string, it will be converted to a string using to_s
. Returns the number of bytes written.
count = $stdout.write("This is a test\n") puts "That was #{count} bytes of data"
produces:
This is a test That was 15 bytes of data
static VALUE io_write_m(VALUE io, VALUE str) { return io_write(io, str, 0); }
Writes the given string to ios using the write(2) system call after O_NONBLOCK is set for the underlying file descriptor.
It returns the number of bytes written.
write_nonblock
just calls the write(2) system call. It causes all errors the write(2) system call causes: Errno::EWOULDBLOCK, Errno::EINTR, etc. The result may also be smaller than string.length (partial write). The caller should care such errors and partial write.
If the exception is Errno::EWOULDBLOCK or Errno::EAGAIN, it is extended by IO::WaitWritable
. So IO::WaitWritable
can be used to rescue the exceptions for retrying write_nonblock.
# Creates a pipe. r, w = IO.pipe # write_nonblock writes only 65536 bytes and return 65536. # (The pipe size is 65536 bytes on this environment.) s = "a" #100000 p w.write_nonblock(s) #=> 65536 # write_nonblock cannot write a byte and raise EWOULDBLOCK (EAGAIN). p w.write_nonblock("b") # Resource temporarily unavailable (Errno::EAGAIN)
If the write buffer is not empty, it is flushed at first.
When write_nonblock
raises an exception kind of IO::WaitWritable
, write_nonblock
should not be called until io is writable for avoiding busy loop. This can be done as follows.
begin result = io.write_nonblock(string) rescue IO::WaitWritable, Errno::EINTR IO.select(nil, [io]) retry end
Note that this doesn't guarantee to write all data in string. The length written is reported as result and it should be checked later.
On some platforms such as Windows, write_nonblock
is not supported according to the kind of the IO
object. In such cases, write_nonblock
raises Errno::EBADF
.
By specifying `exception: false`, the options hash allows you to indicate that write_nonblock
should not raise an IO::WaitWritable
exception, but return the symbol :wait_writable instead.
# File prelude.rb, line 131 def write_nonblock(buf, exception: true) __write_nonblock(buf, exception) end
Private Instance Methods
# File lib/scanf.rb, line 682 def block_scanf(str) final = [] # Sub-ideal, since another FS gets created in scanf. # But used here to determine the number of specifiers. fstr = Scanf::FormatString.new(str) last_spec = fstr.last_spec begin current = scanf(str) break if current.empty? final.push(yield(current)) end until eof || fstr.last_spec_tried == last_spec return final end
# File lib/scanf.rb, line 673 def soak_up_spaces c = getc ungetc(c) if c until eof ||! c || /\S/.match(c.chr) c = getc end ungetc(c) if (c && /\S/.match(c.chr)) end