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chgrp
Example usage of chgrp command to change the files' groups
Developer	AT&T Bell Laboratories
Initial release	May 1975; 50 years ago
Written in	Plan 9: C
Operating system	Unix, Unix-like, Plan 9, Inferno, IBM i
Platform	Cross-platform
Type	Command
License	Plan 9: MIT License

chgrp, short for change group, is a shell command for changing the group associated with a Unix-based file system file – including special files such as directories. Changing the group of a file is restricted to a super-user (such as via sudo) or to the file's owning user if the user is in the specified group.

A file has access permissions for the owning user, a group and for others. Changing the group for a file changes access to it based on users' group memberships.

The chgrp command was originally developed as part of the Unix operating system by AT&T Bell Laboratories. It is available in most Unix-like systems, Plan 9, Inferno and IBM i.^[1]

The version of chgrp bundled in GNU coreutils was written by David MacKenzie.^[2]

Generally, the syntax can be described as:

chgrp [options] group files

• group specifies the group with which the files should be associated; may be either a symbolic name or an identifier
• files specifies one or more files, which may be the result of a glob expression like *.conf

Options:

• -R Recurse through directories
• -v Verbose output: log the name of each file changed
• -f Force or forge ahead even if an error occurs

The following demonstrates changing the group of files matching *.conf to staff – provided the user owns the files (is gbeeker) and is a member of staff. The change will allow members of the group staff to modify the files since the group-class permissions (read/write) will apply, not the others-class permissions (read only).

$ ls -l *.conf
-rw-rw-r--   1 gbeeker  wheel          3545 Nov 04 2011  prog.conf
-rw-rw-r--   1 gbeeker  wheel          3545 Nov 04 2011  prox.conf
$ chgrp staff *.conf
$ ls -l *.conf
-rw-rw-r--   1 gbeeker  staff          3545 Nov 04 2011  prog.conf
-rw-rw-r--   1 gbeeker  staff          3545 Nov 04 2011  prox.conf

• chmod – Shell command for changing access permissions of a file
• chown – Shell command for changing the owner of a file
• Group identifier (Unix) – Unix/POSIX system account group number; numeric value used to represent a specific group
• List of POSIX commands

• chgrp: change the file group ownership – Shell and Utilities Reference, The Single UNIX Specification, Version 5 from The Open Group
• chgrp(1) – Plan 9 Programmer's Manual, Volume 1
• chgrp(1) – Inferno General commands Manual