id - phpMan

File:,  Node: id invocation,  Next: logname invocation,  Up: User information
20.1 `id': Print user identity
`id' prints information about the given user, or the process running it
if no user is specified.  Synopsis:
     id [OPTION]... [USERNAME]
   By default, it prints the real user ID, real group ID, effective
user ID if different from the real user ID, effective group ID if
different from the real group ID, and supplemental group IDs.  In
addition, if SELinux is enabled and the `POSIXLY_CORRECT' environment
variable is not set, then print `context=C', where C is the security
   Each of these numeric values is preceded by an identifying string and
followed by the corresponding user or group name in parentheses.
   The options cause `id' to print only part of the above information.
Also see *note Common options::.
     Print only the group ID.
     Print only the group ID and the supplementary groups.
     Print the user or group name instead of the ID number.  Requires
     `-u', `-g', or `-G'.
     Print the real, instead of effective, user or group ID.  Requires
     `-u', `-g', or `-G'.
     Print only the user ID.
     Print only the security context of the current user.  If SELinux
     is disabled then print a warning and set the exit status to 1.

   An exit status of zero indicates success, and a nonzero value
indicates failure.
   Primary and supplementary groups for a process are normally inherited
from its parent and are usually unchanged since login.  This means that
if you change the group database after logging in, `id' will not
reflect your changes within your existing login session.  Running `id'
with a user argument causes the user and group database to be consulted
afresh, and so will give a different result.