module FileUtils

Namespace for file utility methods for copying, moving, removing, etc.

What’s Here ↑

First, what’s elsewhere. Module FileUtils:

Here, module FileUtils provides methods that are useful for:

Creating ↑

Deleting ↑

Querying ↑

Setting ↑

Comparing ↑

Copying ↑

Moving ↑

Options ↑

Path Arguments ↑

Some methods in FileUtils accept path arguments, which are interpreted as paths to filesystem entries:

About the Examples ↑

Some examples here involve trees of file entries. For these, we sometimes display trees using the tree command-line utility, which is a recursive directory-listing utility that produces a depth-indented listing of files and directories.

We use a helper method to launch the command and control the format:

def tree(dirpath = '.')
  command = "tree --noreport --charset=ascii #{dirpath}"
  system(command)
end

To illustrate:

tree('src0')
# => src0
#    |-- sub0
#    |   |-- src0.txt
#    |   `-- src1.txt
#    `-- sub1
#        |-- src2.txt
#        `-- src3.txt

Avoiding the TOCTTOU Vulnerability ↑

For certain methods that recursively remove entries, there is a potential vulnerability called the Time-of-check to time-of-use, or TOCTTOU, vulnerability that can exist when:

To avoid that vulnerability, you can use this method to remove entries:

Also available are these methods, each of which calls FileUtils.remove_entry_secure:

Finally, this method for moving entries calls FileUtils.remove_entry_secure if the source and destination are on different file systems (which means that the “move” is really a copy and remove):

Method FileUtils.remove_entry_secure removes securely by applying a special pre-process:

WARNING: You must ensure that ALL parent directories cannot be moved by other untrusted users. For example, parent directories should not be owned by untrusted users, and should not be world writable except when the sticky bit is set.

For details of this security vulnerability, see Perl cases: