chgrp

  • This function’s solution assumes a Unix-like operating system.

    The chgrp function in PHP will change the group of a file to a different group ID, assuming the PHP process has sufficient privileges to do so.

    PHP

    chgrp('/path/to/foobar', 501);

    Ruby’s File.chown class method is used to accomplish the same task.

    Ruby

    File.chown(nil, 501, '/path/to/foobar')

    The first argument of File.chown is the user, the second is the group, and the third is the file. Above, the user is set to nil. This will leave the user unchanged.

    Changing the Group by Name

    One nice feature of PHP’s chown is that the $group argument is mixed. It can accept either a group ID or a group name.

    PHP

    chown('/path/to/foobar', 'herbert');

    File.chown from Ruby is not as flexible. It only accepts numeric IDs. To change the group by name, we must first perform a lookup to get the group ID from the name.

    The Etc module from the Ruby Standard Library contains a method getgrnam that returns a Struct of information about a group by name, which includes the group ID. We can use this lookup the group ID and then pass it to File.chown.

    Ruby

    require 'etc'
 
gid = Etc.getgrnam('herbert').gid
File.chown(nil, gid, '/path/to/foobar')

    Changing the Group with FileUtils

    An alternative to using File and Etc to change the group of a file is to use FileUtils, also from the Ruby Standard Library. FileUtils.chown can change the group by either group ID or name.

    Ruby

    require 'fileutils'
 
# equivalent
FileUtils.chown(nil, 501, '/path/to/foobar')
FileUtils.chown(nil, 'herbert', '/path/to/foobar')

    The first argument of FileUtils.chown is the user, the second is the group, and the third is the file. Above, the user is set to nil. This will leave the user unchanged.

    Another useful method is FileUtils.chown_R, whose usage is the same but will recursively change all files in a given path.

    see also

← chdir chmod →

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