Forgot your password?
New user?
What is crontab?
Document Actions
su
su
Next: tail Up: Man Pages Previous: shutdown
su
NAME
su - run a shell with substitute user and group IDs
SYNOPSIS
su [-flmp] [-c command] [-s shell] [-login] [-fast] [-preserve-environment] [-command=command] [-shell=shell] [-] [-help] [-version] [user [arg...]]
DESCRIPTION
This documentation is no longer being maintained and may be inaccurate or incomplete. The Texinfo documentation is now the authoritative source.
This manual page documents the GNU version of su. su allows one user to temporarily become another user. It runs a shell with the real and effective user ID, group ID, and supplemental groups of USER. If no USER is given, the default is root, the super-user. The shell run is taken from USER's password entry, or /bin/sh if none is specified there. If USER has a password, su prompts for the password unless run by a user with real user ID 0 (the super-user). By default, su does not change the current directory. It sets the environment variables `HOME' and `SHELL' from the password entry for USER, and if USER is not the super- user, sets `USER' and `LOGNAME' to USER. By default, the shell is not a login shell. If one or more ARGs are given, they are passed as additional arguments to the shell. su does not handle /bin/sh or other shells specially (setting argv[0] to "-su", passing -c only to certain shells, etc.). On systems that have syslog, su can be compiled to report failed, and optionally successful, su attempts using sys- log.
OPTIONS
- -c COMMAND, -command=COMMAND
- Pass COMMAND, a single command line to run, to the shell with a -c option instead of starting an interactive shell.
- -f, -fast
- Pass the -f option to the shell. This probably only makes sense with csh and tcsh, for which the -f option prevents reading the startup file (.cshrc). With Bourne-like shells, the -f option disables filename pattern expansion, which is not a generally desirable thing to do.
- -help
- Print a usage message on standard output and exit successfully.
- -, -l, -login
- Make the shell a login shell. This means the following. Unset all environment variables except `TERM', `HOME', and `SHELL' (which are set as described above), and `USER' and `LOGNAME' (which are set, even for the super-user, as described above), and set `PATH' to a compiled-in default value. Change to USER's home directory. Prepend "-" to the shell's name, to make it read its login startup file(s).
- -m, -p, -preserve-environment
- Do not change the environment variables `HOME', `USER', `LOGNAME', or `SHELL'. Run the shell given in the environment variable `SHELL' instead of USER's shell from /etc/passwd, unless the user running su is not the superuser and USER's shell is restricted. A restricted shell is one that is not listed in the file /etc/shells, or in a compiled-in list if that file does not exist. Parts of what this option does can be overridden by -login and -shell.
- -s, -shell
- shell Run SHELL instead of USER's shell from /etc/passwd, unless the user running su is not the superuser and USER's shell is restricted.
- -version
- Print version information on standard output then exit successfully.
EXAMPLES
Next: tail Up: Man Pages Previous: shutdown
2005-05-10