Copyright (c) 1983 Regents of the University of California.
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@(#)groups.1 6.1 (Berkeley) 04/29/85

C 5 groups - show group memberships groups [user] The 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 /etc/passwd and possibly to other groups as specified in the file /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.

When a new file is created it is given the group of the containing directory.

setgroups(2) /etc/passwd, /etc/group More groups should be allowed.