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)