SU(1)
NAME
su − substitute user ID temporarily
USAGE
su [ userid ]
DESCRIPTION
Su makes a temporary substitution of the current userid for the one specified. However, you must first supply the correct password of the specified userid. If you provide this information, su invokes a new Shell, either sh(1) or csh(1), and recognizes you as the user for which you supplied the userid. It is important to note that su does not change the current directory when the substitution takes place. The user environment remains unchanged except for HOME and SHELL, which are taken from the password file for the user being substituted. See environ(7) for more information about the user environment. The new user ID stays in force until the Shell exits.
If you do not supply a userid, su assumes it to be root. To remind the super-user of his or her responsibilities, the Shell substitutes a pound sign (#) for its usual prompt.
All attempts to become another user using su are logged in the log file /etc/sulog.
CAUTIONS
Local administrative rules cause restrictions to be placed on who can su to root, even with the root password. These rules vary from site to site.
FILES
/etc/passwd
system’s password file
/etc/sulog
log file