chgrp is a utility that changes the group associated with a file.

A file belongs to a user and to a group where one or more users could be associated.

It is similar to chown but chgrp only changes the group and not the owner of the file, while chown can change both of them. Usage

chgrp [options] group file-list

or <p class="codigo">chgrp [options] –reference=rfile file-list</p>

group:
Is the name or numeric group ID of the new group to assigned to file-list
file-list
Is a list of the pathnames of the files whose group association is going to be changed.
rfile
Is the pathname of a file whose group is going to become the new group associated to the file-list

Options

   -c, --changes
          Verbosely describe the action for each file whose group actually
          changes.

   -f, --silent, --quiet
          Do  not  print  error messages about files whose group cannot be
          changed.

   -h, --no-dereference
          Act on symbolic links themselves instead of what they point  to.
          Only available if the lchown system call is provided.

   -v, --verbose
          Verbosely  describe  the  action  or  non-action taken for every
          file.

   -R, --recursive
          Recursively change the group ownership of directories and  their
          contents.

Be aware that only the owner of a file or root will be able to change the group associated with that file.