module File::Constants
File::Constants provides file-related constants.  All possible file constants are listed in the documentation but they may not all be present on your platform.
If the underlying platform doesn’t define a constant the corresponding Ruby constant is not defined.
Your platform documentations (e.g. man open(2)) may describe more detailed information.
Constants
- APPEND
- append on each write 
- BINARY
- disable line code conversion 
- CREAT
- create file if it does not exist 
- DIRECT
- Try to minimize cache effects of the I/O to and from this file. 
- DSYNC
- any write operation perform synchronously except some meta data 
- EXCL
- error if - CREATand the file exists
- FNM_CASEFOLD
- Makes - File.fnmatchpatterns case insensitive (but not- Dir.globpatterns).
- FNM_DOTMATCH
- The ‘*’ wildcard matches filenames starting with “.” in - File.fnmatchand- Dir.globpatterns
- FNM_EXTGLOB
- Allows file globbing through “{a,b}” in - File.fnmatchpatterns.
- FNM_NOESCAPE
- Disables escapes in - File.fnmatchand- Dir.globpatterns
- FNM_PATHNAME
- Wildcards in - File.fnmatchand- Dir.globpatterns do not match directory separators
- FNM_SHORTNAME
- Makes patterns to match short names if existing. Valid only on Microsoft Windows. 
- FNM_SYSCASE
- System default case insensitiveness, equals to - FNM_CASEFOLDor 0.
- LOCK_EX
- exclusive lock. see - File#flock
- LOCK_NB
- non-blocking lock. used with - LOCK_SHor- LOCK_EX. see- File#flock
- LOCK_SH
- shared lock. see - File#flock
- LOCK_UN
- unlock. see - File#flock
- NOATIME
- do not change atime 
- NOCTTY
- not to make opened - IOthe controlling terminal device
- NOFOLLOW
- do not follow symlinks 
- NONBLOCK
- do not block on open or for data to become available 
- NULL
- Name of the null device 
- RDONLY
- open for reading only 
- RDWR
- open for reading and writing 
- RSYNC
- any read operation perform synchronously. used with - SYNCor- DSYNC.
- SHARE_DELETE
- can delete opened file 
- SYNC
- any write operation perform synchronously 
- TMPFILE
- Create an unnamed temporary file 
- TRUNC
- truncate size to 0 
- WRONLY
- open for writing only