Create a shell with the effective user ID of another
user (that is,
user). If no
user is specified, create a shell for a
privileged user (that is, become a superuser). Enter
EOF to terminate.
You can run the shell with particular options by passing them
shell_args (e.g., if the shell runs sh, you can specify
command to execute
command via sh,
or -r to create a restricted shell).
Go through the entire login sequence (i.e., change to