ID(8) Maintenance Commands and Procedures ID(8)

NAME

id - return user identity

SYNOPSIS

/usr/bin/id [-p] [user]


/usr/bin/id -a [-p] [user]


/usr/bin/id -G [-n] [user]


/usr/bin/id -g [-nr] [user]


/usr/bin/id -u [-nr] [user]


/usr/xpg4/bin/id [-p] [user]


/usr/xpg4/bin/id -a [-p] [user]


/usr/xpg4/bin/id -G [-n] [user]


/usr/xpg4/bin/id -g [-nr] [user]


/usr/xpg4/bin/id -u [-nr] [user]

DESCRIPTION

If no user operand is provided, the id utility writes the user and group
IDs and the corresponding user and group names of the invoking process to
standard output. If the effective and real IDs do not match, both are
written. If multiple groups are supported by the underlying system,
/usr/xpg4/bin/id also writes the supplementary group affiliations of the
invoking process.


If a user operand is provided and the process has the appropriate
privileges, the user and group IDs of the selected user are written. In
this case, effective IDs are assumed to be identical to real IDs. If the
selected user has more than one allowable group membership listed in the
group database, /usr/xpg4/bin/id writes them in the same manner as the
supplementary groups described in the preceding paragraph.

Formats

The following formats are used when the LC_MESSAGES locale category
specifies the "C" locale. In other locales, the strings uid, gid, euid,
egid, and groups may be replaced with more appropriate strings
corresponding to the locale.

"uid=%u(%s) gid=%u(%s)\n" <real user ID>, <user-name>,
<real group ID>, <group-name>


If the effective and real user IDs do not match, the following are
inserted immediately before the \n character in the previous format:

" euid=%u(%s)"


with the following arguments added at the end of the argument list:

<effective user ID>, <effective user-name>


If the effective and real group IDs do not match, the following is
inserted directly before the \n character in the format string (and after
any addition resulting from the effective and real user IDs not
matching):

" egid=%u(%s)"


with the following arguments added at the end of the argument list:

<effectivegroup-ID>, <effectivegroupname>


If the process has supplementary group affiliations or the selected user
is allowed to belong to multiple groups, the first is added directly
before the NEWLINE character in the format string:

" groups=%u(%s)"


with the following arguments added at the end of the argument list:

<supplementary group ID>, <supplementary group name>


and the necessary number of the following added after that for any
remaining supplementary group IDs:

",%u(%s)"


and the necessary number of the following arguments added at the end of
the argument list:

<supplementary group ID>, <supplementary group name>


If any of the user ID, group ID, effective user ID, effective group ID or
supplementary/multiple group IDs cannot be mapped by the system into
printable user or group names, the corresponding (%s) and name argument
is omitted from the corresponding format string.


When any of the options are specified, the output format is as described
under OPTIONS.

OPTIONS

The following options are supported by both /usr/bin/id and
/usr/xpg4/bin/id. The -p and -a options are invalid if specified with any
of the -G, -g, or -u options.

-p
Reports additionally the current project membership of the invoking
process. The project is reported using the format:

"projid=%u(%s)"


which is inserted prior to the \n character of the default format
described in the Formats section. The arguments

<project ID>,<project name>


are appended to the end of the argument list. If the project ID
cannot be mapped by the system into a printable project name, the
corresponding (%s) and name argument is omitted from the
corresponding format string.


-a
Reports user name, user ID and all the groups to which the user
belongs.


-G
Outputs all different group IDs (effective, real and supplementary)
only, using the format "%u\n". If there is more than one distinct
group affiliation, output each such affiliation, using the format "
%u", before the NEWLINE character is output.


-g
Outputs only the effective group ID, using the format "%u\n".


-n
Outputs the name in the format "%s" instead of the numeric ID using
the format "%u".


-r
Outputs the real ID instead of the effective ID.


-u
Outputs only the effective user ID, using the format "%u\n".

OPERANDS

The following operand is supported:

user
The user (login) name for which information is to be written.

ENVIRONMENT VARIABLES

See environ(7) for descriptions of the following environment variables
that affect the execution of id: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES, and
NLSPATH.

EXIT STATUS

The following exit values are returned:

0
Successful completion.


>0
An error occurred.

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:

/usr/bin/id


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Stable |
+--------------------+-----------------+

/usr/xpg4/bin/id


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+

SEE ALSO

fold(1), logname(1), who(1), getgid(2), getgroups(2), getprojid(2),
getuid(2), attributes(7), environ(7), standards(7)

NOTES

Output produced by the -G option and by the default case could
potentially produce very long lines on systems that support large numbers
of supplementary groups.

September 10, 2013 ID(8)