Su (computing)

The Unix su (subsitute user) command is used to assume the login shell of another user without logging out. It is commonly used to change to root user permissions for administrative work. Desktop environments such as KDE and GNOME have programs that pop up a password query box before allowing a user to run commands that would typically require such access.

A related command called sudo executes a command as another user but does not start a login shell, similar to using su -c.

See also: Unix security