Sudo allows a user to run commands as the superuser or another user with certain permissions. It is commonly used when a user needs elevated privileges for a specific task without logging in as the root user. The sudoers file defines which commands can be run with sudo for each user or group. To use sudo, a user must be granted permission via the sudoers file and enter their own password when prompted, unless the timestamp is still valid within the timeout period.
1. SUDO
sudo is a Linux command used to execute programs as the root, or "super
user." sudo is a shortening of "super user do." One uses sudo when they need to run
a command or program as root, but do not wish to log out or switch their entire
shell to root privileges (like they could do with the sudo command).
The file sudoers defines per user or per group what commands can be run with
sudo. This file is edited with the command visudoers
command: sudo /opt/lampp/lampp
The above command is used for check whether lampp is installed are not.....
command: sudo /opt/lampp/lampp/start
The above command is used for start the lampp
command: sudo /opt/lampp/lampp/stop
The above command is used for start the lampp
The following procedure will guide you to work in sudo:
1. Log in Linux graphical mode as usual, answering your username and
password
2. Open a terminal, shell window.
3. at the bash shell prompt $ type sudo -v
4. Linux will ask you for a password -- enter the password of your account For
the next 5 minutes it will not ask you for your password when you use sudo.
5. After Linux returns the bash shell prompt $ type sudo su - Since you already
have root privileges, it will not ask you for the root password
6.Linux will reply with something like [root@mislab01x root]#
Linux accepts your login as root and gives you the root path. You are now ready
to start X Windows as root!
7.at the prompt # type startx -- :1 vt8 This will start another X Windows session
with root privileges
8.You can now use all graphical tools requiring root privileges.
About sudo:
2. Allows a user with proper permissions to execute a command as the
superuser or other user.
Syntax
sudo -K | -L | -V | -h | -k | -l | -v
sudo [-HPSb] [-a auth_type] [-c class|-] [-p prompt] [-u username|#uid] {-e file [...] |
-i | -s | command}
-H The -H (HOME) option sets the HOME environment variable to the homedir
of the target user (root by default) as specified in passwd. By default, sudo
does not modify HOME (see set_home and always_set_home in sudoers).
-K The -K (sure kill) option is like -k except that it removes the user's
timestamp entirely. Like -k, this option does not require a password.
-L The -L (list defaults) option will list out the parameters that may be set in a
Defaults line along with a short description for each. This option is useful in
conjunction with grep.
-P The -P (preserve group vector) option causes sudo to preserve the invoking
user's group vector unaltered. By default, sudo will initialize the group
vector to the list of groups the target user is in. The real and effective group
IDs, however, are still set to match the target user.
-S The -S (stdin) option causes sudo to read the password from the standard
input instead of the terminal device.
-V The -V (version) option causes sudo to print the version number and exit. If
the invoking user is already root the -V option will print out a list of the
defaults sudo was compiled with as well as the machine's local network
addresses.
-a The -a (authentication type) option causes sudo to use the specified
authentication type when validating the user, as allowed by /etc/login.conf.
The system administrator may specify a list of sudo-specific authentication
methods by adding an "auth-sudo" entry in /etc/login.conf. This option is
only available on systems that support BSD authentication where sudo has
been configured with the --with-bsdauth option.
-b The -b (background) option tells sudo to run the given command in the
background. Note that if you use the -b option you cannot use shell job
control to manipulate the process.
-c The -c (class) option causes sudo to run the specified command with
resources limited by the specified login class. The class argument can be
either a class name as defined in /etc/login.conf, or a single '-' character.
Specifying a class of - indicates that the com-
3. mand should be run restricted by the default login capabilities for the user
the command is run as. If the class argument specifies an existing user
class, the command must be run as root, or the sudo command must be
run from a shell that is already root. This option
is only available on systems with BSD login classes where sudo has been
configured with the --with-logincap option.
-e The -e (edit) option indicates that, instead of running a command, the user
wishes to edit one or more files. In lieu of a command, the string
"sudoedit" is used when consulting the sudoers file. If the user is
authorized by sudoers the following steps are taken:
5. -h The -h (help) option causes sudo to print a usage message and exit.
-i The -i (simulate initial login) option runs the shell specified in the passwd
entry of the user that the command is being run as. The command name
argument given to the shell begins with a - to tell the shell to run as a login
shell. sudo attempts to change to that user's home directory before
running the shell. It also initializes the environment, leaving TERM
unchanged, setting HOME, SHELL, USER, LOGNAME, and PATH, and
unsetting all other environment variables. Note that because the shell to
use is determined before the sudoers file is parsed, a runas_default setting
in sudoers will specify the user to run the shell as but will not affect which
shell is actually run.
-k The -k (kill) option to sudo invalidates the user's timestamp by setting the
time on it to the epoch. The next time sudo is run a password will be
required. This option does not require a password and was added to allow
a user to revoke sudo permissions from a .logout file.
-l The -l (list) option will list out the allowed (and forbidden) commands for
the user on the current host.
-p The -p (prompt) option allows you to override the default password prompt
and use a custom one. The following percent (`%') escapes are supported:
7. -s The -s (shell) option runs the shell specified by the SHELL environment
variable if it is set or the shell as specified in passwd.
-u The -u (user) option causes sudo to run the specified command as a user
other than root. To specify a uid instead of a username, use #uid. Note that
if the targetpw Defaults option is set (see sudoers) it is not possible to run
commands with a uid not listed in the password database.
-v If given the -v (validate) option, sudo will update the user's timestamp,
prompting for the user's password if necessary. This extends the sudo
timeout for another 5 minutes (or whatever the timeout is set to in
sudoers) but does not run a command.
-- The -- flag indicates that sudo should stop processing command line
arguments. It is most useful in conjunction with the -s flag.