4.2BSD/usr/man/man1/groups.1

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.TH GROUPS 1 "30 May 1983"
.UC 4
.SH NAME
groups \- show group memberships
.SH SYNOPSIS
.B
groups [user]
.SH DESCRIPTION
The
.I groups
command shows the groups to which you or the optionally specified
user belong.
Each user belongs to a group specified in the password file
.I /etc/passwd
and possibly to other groups as specified in the file
.IR /etc/group .
If you do not own a file but belong to the group which it is owned
by then you are granted group access to the file.
.PP
When a new file is created it is given
the group of the containing directory.
.SH "SEE ALSO"
setgroups(2)
.SH FILES
/etc/passwd, /etc/group
.SH BUGS
More groups should be allowed.