Linux in a Nutshell, Fifth Edition

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Chapter 3: Linux Commands

This is the Title of the Book, eMatter Edition

Copyright © 2006 O’Reilly & Associates, Inc. All rights reserved.

-c command, --command=command

Execute command in the new shell and then exit immediately.

If command is more than one word, it should be enclosed in

quotes. For example:

su -c 'find / -name \*.c -print' nobody

-f, --fast

Start the shell with the -f option, which suppresses the reading

of the .cshrc or .tcshrc file. Applies to csh and tcsh.

-m, -p, --preserve-environment

Do not reset environment variables.

-s shell, --shell=shell

Execute shell, not the shell specified in /etc/passwd, unless shell

is restricted.

--help

Print a help message and then exit.

--version

Print version information and then exit.

Examples

Become root and obtain all of root’s user environment:

$ su -

Become root long enough to restart the Apache httpd web server,

then revert to the current user:

$ su -c /etc/rc.d/init.d/httpd restart

sudo

sudo [options] [command]

If you are allowed, execute command as the superuser. Authorized

users of sudo and the commands they are permitted to execute are

listed in the sudo configuration file, /etc/sudoers. If an unautho-

rized user attempts to run a command, sudo will inform an

administrator via email. By default, it will send the message to the

root account. Users attempting to run commands are prompted for

their password. Once authenticated, sudo sets a timestamp ...