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id(1) [opendarwin man page]

ID(1)							    BSD General Commands Manual 						     ID(1)

NAME
id -- return user identity SYNOPSIS
id [user] id -G [-n] [user] id -P [user] id -g [-nr] [user] id -p [user] id -u [-nr] [user] DESCRIPTION
The id utility displays the user and group names and numeric IDs, of the calling process, to the standard output. If the real and effective IDs are different, both are displayed, otherwise only the real ID is displayed. If a user (login name or user ID) is specified, the user and group IDs of that user are displayed. In this case, the real and effective IDs are assumed to be the same. The options are as follows: -G Display the different group IDs (effective, real and supplementary) as white-space separated numbers, in no particular order. -P Display the id as a password file entry. -g Display the effective group ID as a number. -n Display the name of the user or group ID for the -G, -g and -u options instead of the number. If any of the ID numbers cannot be mapped into names, the number will be displayed as usual. -p Make the output human-readable. If the user name returned by getlogin(2) is different from the login name referenced by the user ID, the name returned by getlogin(2) is displayed, preceded by the keyword ``login''. The user ID as a name is displayed, preceded by the keyword ``uid''. If the effective user ID is different from the real user ID, the real user ID is displayed as a name, preceded by the keyword ``euid''. If the effective group ID is different from the real group ID, the real group ID is displayed as a name, preceded by the keyword ``rgid''. The list of groups to which the user belongs is then displayed as names, preceded by the keyword ``groups''. Each display is on a separate line. -r Display the real ID for the -g and -u options instead of the effective ID. -u Display the effective user ID as a number. DIAGNOSTICS
The id utility exits 0 on success, and >0 if an error occurs. SEE ALSO
who(1) STANDARDS
The id function is expected to conform to IEEE Std 1003.2 (``POSIX.2''). HISTORY
The historic groups(1) command is equivalent to ``id -Gn [user]''. The historic whoami(1) command is equivalent to ``id -un''. The id command appeared in 4.4BSD. BSD
June 6, 1993 BSD

Check Out this Related Man Page

NEWGRP(1)						    BSD General Commands Manual 						 NEWGRP(1)

NAME
newgrp -- change to a new primary group SYNOPSIS
newgrp [-l] [group] DESCRIPTION
The newgrp command changes a user to a new primary group (real and effective group ID) by starting a new shell. The user remains logged in and the current directory and file creation mask remain unchanged. The user is always given a new shell even if the primary group change fails. The newgrp command accepts the following options: -l The environment is changed to what would be expected if the user actually logged in again. This simulates a full login. The group is a group name or non-negative numeric group ID from the group database. The real and effective group IDs are set to group or the group ID associated with the group name. If group is not specified, newgrp restores the user's real and effective group IDs to the user's primary group specified in the password database. The user's supplementary group IDs are restored to the set specified for the user in the group database. If the user is not a member of the specified group, and the group requires a password, the user will be prompted for the group password. FILES
/etc/group The group database /etc/master.passwd The user database /etc/passwd A Version 7 format password file EXIT STATUS
If a new shell is started the exit status is the exit status of the shell. Otherwise the exit status will be >0. SEE ALSO
csh(1), groups(1), login(1), sh(1), su(1), umask(2), group(5), passwd(5), environ(7) STANDARDS
The newgrp command conforms to IEEE Std 1003.1-2001 (``POSIX.1''). HISTORY
A newgrp command appeared in Version 6 AT&T UNIX. A newgrp command appeared in NetBSD 5.0. BUGS
There is no convenient way to enter a password into /etc/group. The use of group passwords is strongly discouraged since they are inherently insecure. It is not possible to stop users from obtaining the encrypted password from the group database. BSD
June 6, 2007 BSD
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