Check to Se if User Is art of Sudo

sudo (Southuper User DO) command in Linux is generally used equally a prefix of some control that just superuser are allowed to run. If you prefix "sudo" with whatsoever control, it will run that command with elevated privileges or in other words allow a user with proper permissions to execute a command every bit another user, such as the superuser. This is the equivalent of "run as administrator" option in Windows. The option of sudo lets usa have multiple administrators.
These users who can utilise the sudo command demand to have an entry in the sudoers file located at "/etc/sudoers". Remember that to edit or view the sudoers file you have to use sudo control. To edit the sudoers file information technology is recommended to use "visudo" command.
By default, sudo requires that users authenticate themselves with a password which is the user's password, non the root password itself.

sudoers file:

Syntax:

sudo -V | -h | -50 | -5 | -k | -K | -s | [ -H ] [-P ] [-Due south ] [ -b ] |
[ -p prompt ] [ -c course|- ] [ -a auth_type ] [-r function ] [-t type ]
[ -u username|#uid ] commandsudo -V | -h | -50 | -L | -5 | -m | -K | -s | [ -H ] [-P ] [-S ] [ -b ] |
[ -p prompt ] [ -c course|- ] [ -a auth_type ] [-r role ] [-t type ]
[ -u username|#uid ] control

Options

1. -Five: The -V (version) option causes sudo to impress the version number and go out. If the invoking user is already root, the -V selection volition print out a list of the defaults sudo was compiled with.

ii. -fifty: The -l (listing) option will print out the commands allowed (and forbidden) the user on the current host.

This shows the current user can use all commands as sudo.

3. -h or –assist: The -h (help) pick causes sudo to print a usage message and exit.

4. -v: If, given the -v (validate) pick, sudo will update the user'southward timestamp, prompting for the user's password if necessary. This extends the sudo timeout for another v minutes (or as given in sudoers) simply does not run a command. This does non give any output.

5. -k: The -k (kill) option to sudo invalidates the user's timestamp.And so, the next time sudo is run a password will be required. This choice does not require a password and was added to allow a user to revoke sudo permissions from a .logout file.

six. -K: Similar to the -k option, the -K (sure impale) option is used to remove the user's timestamp entirely. As well, this option does not require a password.

7. -b: The -b (background) option tells sudo to run the given command in the background. Notation that if you lot use the -b option you cannot use vanquish job command to manipulate the process.

8. -p:The -p (prompt) option allows y'all to override the default password prompt and employ a custom one. The following per centum ('%') escapes are supported:

%u is expanded to the invoking user's login name;

%U is expanded to the login name of the user the command volition be run every bit (which defaults to root);

%h is expanded to the local hostname without the domain proper noun;

%H is expanded to the local hostname including the domain name (just if the machine'south hostname is fully qualified or the "fqdn" sudoers option is prepare);

%% (two consecutive % characters) are collapsed into a single % grapheme.

Normally we become this for a sudo control:

Using sudo -p nosotros go,

9. -north: Employ -n choice as shown below, which will execute the command without prompting for the password. This is very helpful when we desire to run some of the sudo commands as background jobs (or in a shell script), where nosotros don't want sudo to ask for the password. -north option stands for non-interactive.

10. -u: The -u (user) option causes sudo to run the specified control as a user other than root. To specify a uid instead of a username, employ #uid.

xi. -s: The -s (shell) option runs the shell specified past the Vanquish environment variable if information technology is set or the trounce every bit specified in the file passwd.

12. -H: The -H (HOME) option sets the HOME environment variable to the dwelling house directory of the target user (root by default) every bit specified in passwd. Past default, sudo does not alter HOME.

13. -South: The -S (stdin) choice causes sudo to read the password from standard input instead of the final device.

fourteen. -a: The -a (authentication type) option causes sudo to use the specified authentication blazon when validating the user, every bit immune past /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.

15. –: The — flag indicates that sudo should stop processing command line arguments. It is about useful in conjunction with the -s flag.

Environment Variables

These environment variables are used by sudo

Tag	Description
EDITOR	Default editor to use in -eastward (sudoedit) mode if VISUAL is non ready
HOME	In -s or -H fashion (or if sudo was configured with the –enable-crush-sets-home pick), set to homedir of the target user
PATH	Prepare to a sane value if the secure_path sudoers selection is set.
Vanquish	Used to decide vanquish to run with -due south option
SUDO_PROMPT	Used as the default password prompt
SUDO_COMMAND	Ready to the command run past sudo
SUDO_USER	Prepare to the login of the user who invoked sudo
SUDO_UID	Set to the uid of the user who invoked sudo
SUDO_GID	Fix to the gid of the user who invoked sudo
SUDO_PS1	If set, PS1 will be gear up to its value
USER	Prepare to the target user (root unless the -u pick is specified)
VISUAL	Default editor to utilize in -e (sudoedit) mode

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Source: https://www.geeksforgeeks.org/sudo-command-in-linux-with-examples/

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