groups − print the groups a user is in
groups [OPTION]... [USERNAME]...
Print group memberships for each USERNAME or, if no USERNAME is specified, for the current process (which may differ if the groups database has changed).
display this help and exit
output version information and exit
Written by David MacKenzie and James Youngman.
© 2017 Free Software Foundation, Inc. License GPLv3+:
GNU GPL version 3 or later
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.
or available locally via: info '(coreutils) groups invocation'