Section 1: su
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SU(1) SU(1)
NAME
su - Change user ID or become super-user
SYNOPSIS
su [OPTS] [-] [username [ARGS]]
DESCRIPTION
su is used to become another user during a login session.
Invoked without a username, su defaults to becoming the
super user. The optional argument - may be used to pro-
vide an environment similiar to what the user would expect
had the user logged in directly.
The user will be prompted for a password, if appropriate.
Invalid passwords will produce an error message. All
attempts, both valid and invalid, are logged to detect
abuses of the system.
An optional command can be executed. This is done by the
shell specified in /etc/passwd for the target user unless
the -s or -m options are used. Any arguments supplied
after the username will be passed to the invoked shell
(shell must support the -c command line option in order
for a command to be passed to it).
The current environment is passed to the new shell. The
value of $PATH is reset to /bin:/usr/bin for normal users,
or /sbin:/bin:/usr/sbin:/usr/bin for the super user. This
may be changed with the ENV_PATH and ENV_SUPATH defini-
tions in /etc/login.defs. When using the -m or -p options,
the users environment is not changed.
A subsystem login is indicated by the presense of a "*" as
the first character of the login shell. The given home
directory will be used as the root of a new filesystem
which the user is actually logged into.
OPTIONS
- make this a login shell
-c, --commmand=
pass command to the invoked shell using its -c
option
-m, -p, --preserve-environment
do not reset environment variables, and keep the
same shell
-s, --shell=
use shell instead of the default in /etc/passwd
NOTES
The -m, -p and -s options are restricted by the target
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SU(1) SU(1)
user's shell being listed in /etc/shells. If it's not
listed, then it's assumed to be a restricted account, a
normal su is performed, and those options are ignored
silently.
CAVEATS
This version of su has many compilation options, only some
of which may be in use at any particular site.
Files
/etc/passwd - user account information
/etc/shadow - encrypted passwords and age information
/etc/shells - valid user shells
$HOME/.profile - initialization script for default shell
SEE ALSO
login(1), sh(1), login.defs(5), shells(5)
AUTHOR
Julianne Frances Haugh (jfh@bga.com)
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