su(1M) — ADMINISTRATOR COMMANDS

NAME

su − become super-user or another user

SYNOPSIS

su [ − ] [ name [ arg ... ] ]

DESCRIPTION

su allows one to become another user without logging off. The default user name is root (that is, super-user).

To use su, the appropriate password must be supplied (unless one is already root). If the password is correct, su will execute a new shell with the real and effective user and group IDs and supplementary group list set to that of the specified user. The new shell will be the optional program named in the shell field of the specified user’s password file entry [see passwd(4)] or /usr/bin/sh if none is specified [see sh(1)]. Note that if /usr/bin/sh is not available, /sbin/sh will be used as the default. To restore normal user ID privileges, type an EOF character (CTRL-d) to the new shell.

Any additional arguments given on the command line are passed to the program invoked as the shell. When using programs such as sh, an arg of the form −c string executes string via the shell and an arg of −r gives the user a restricted shell.

The following statements are true only if the optional program named in the shell field of the specified user’s password file entry is like sh. If the first argument to su is a −, the environment will be changed to what would be expected if the user actually logged in as the specified user. This is done by invoking the program used as the shell with an arg0 value whose first character is −, thus causing first the system’s profile (/etc/profile) and then the specified user’s profile (.profile in the new HOME directory) to be executed. Otherwise, the environment is passed along with the possible exception of $PATH, which is set to /sbin:/usr/sbin:/usr/bin:/etc for root. Note that if the optional program used as the shell is /usr/bin/sh, the user’s .profile can check arg0 for −sh or −su to determine if it was invoked by login or su, respectively. If the user’s program is other than /usr/bin/sh, then .profile is invoked with an arg0 of −program by both login and su.

All attempts to become another user using su are logged in the log file /var/adm/sulog.

EXAMPLES

To become user bin while retaining your previously exported environment, execute:

su bin

To become user bin but change the environment to what would be expected if bin had originally logged in, execute:

su − bin

To execute command with the temporary environment and permissions of user bin, type:

su − bin −c "command args"

FILES

/etc/passwdsystem’s password file
/etc/profilesystem’s profile
$HOME/.profileuser’s profile
/var/adm/suloglog file
/etc/default/suthe default parameters that live here are:

SULOG:
If defined, all attempts to su to
another user are logged in the indicated file.

CONSOLE:
If defined, all attempts to suroot
are logged on the console.

PATH:
Default path.

SUPATH:
Default path for a user invoking suroot.

Museum