Linux sudo command

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Linux sudo command executes instructions as a system administrator, which means that the instructions executed by sudo are as if root executes them personally.

Permissions: In /etc/Users used in sudoers.

Syntax

sudo -V

sudo -h

sudo -l

sudo -v

sudo -k

sudo -s

sudo -H

sudo [ -b ] [ -p prompt ] [ -u username/#uid] -s

sudo command

Parameter description:

• -V Display the version number
• -h Display the version number and usage instructions of the command
• -l Display the permissions of oneself (the user who executes sudo)
• -v Because sudo asks for a password when executed for the first time or if it has not been executed within N minutes (N is preset to five), this parameter is to reconfirm, and if it exceeds N minutes, it will also ask for a password
• -k Force the user to enter a password the next time sudo is executed (regardless of whether it has exceeded N minutes)
• -b Place the command to be executed in the background
• -p prompt You can change the prompt of the password prompt, where 퍕l be replaced by the user's account name, and %h will display the host name
• -u username/#uid Without this parameter, it represents executing the command with root's identity, and with this parameter, it can execute the command with the username's identity (#uid is the user number of the username)
• -s Execute the shell specified by the environment variable SHELL, or /etc/passwd)
• -H Set the HOME (home directory) in the environment variables to the home directory of the user to change identity (if not specified, it will be the shell specified in -u The parameter is the system administrator root )
• command To execute as a system administrator (or with -u Command to be executed by another person (

Online examples

Usage of sudo command

$ sudo ls
[sudo] password for hnlinux: 
hnlinux is not in the sudoers file. This incident will be reported.

Specify the user to execute the command

# sudo -u userb ls -l

Display sudo settings

$ sudo -L //Display sudo settings
Available options in a sudoers 'Defaults' line:
syslog: Syslog facility if syslog is being used for logging
syslog_goodpri: Syslog priority to use when user authenticates successfully
syslog_badpri: Syslog priority to use when user authenticates unsuccessfully
long_otp_prompt: Put OTP prompt on its own line
ignore_dot: Ignore '.' in $PATH
mail_always: Always send mail when sudo is run
mail_badpass: Send mail if user authentication fails
mail_no_user: Send mail if the user is not in sudoers
mail_no_host: Send mail if the user is not in sudoers for this host
mail_no_perms: Send mail if the user is not allowed to run a command
tty_tickets: Use a separate timestamp for each user/tty combo
lecture: Lecture user the first time they run sudo
lecture_file: File containing the sudo lecture
authenticate: Require users to authenticate by default
root_sudo: Root may run sudo
log_host: Log the hostname in the (non-syslog) log file
log_year: Log the year in the (non-syslog) log file
shell_noargs: If sudo is invoked with no arguments, start a shell
set_home: Set $HOME to the target user when starting a shell with -s
always_set_home: Always set $HOME to the target user's home directory
path_info: Allow some information gathering to give useful error messages
fqdn: Require fully-qualified hostnames in the sudoers file
insults: Insult the user when they enter an incorrect password
requiretty: Only allow the user to run sudo if they have a tty
env_editor: Visudo will honor the EDITOR environment variable
rootpw: Prompt for root's password, not the users's
runaspw: Prompt for the runas_default user's password, not the users's
targetpw: Prompt for the target user's password, not the users's
use_loginclass: Apply defaults in the target user's login class if there is one
set_logname: Set the LOGNAME and USER environment variables
stay_setuid: Only set the effective uid to the target user, not the real uid
preserve_groups: Don't initialize the group vector to that of the target user
loglinelen: Length at which to wrap log file lines (0 for no wrap)
timestamp_timeout: Authentication timestamp timeout
passwd_timeout: Password prompt timeout
passwd_tries: Number of tries to enter a password
umask: Umask to use or 0777 to use user's
logfile: Path to log file
mailerpath: Path to mail program
mailerflags: Flags for mail program
mailto: Address to send mail to
mailfrom: Address to send mail from
mailsub: Subject line for mail messages
badpass_message: Incorrect password message
timestampdir: Path to authentication timestamp dir
timestampowner: Owner of the authentication timestamp dir
exempt_group: Users in this group are exempt from password and PATH requirements
passprompt: Default password prompt
passprompt_override: If set, passprompt will override system prompt in all cases.
runas_default: Default user to run commands as
secure_path: Value to override user's $PATH with
editor: Path to the editor for use by visudo
listpw: When to require a password for 'list' pseudocommand
verifypw: When to require a password for 'verify' pseudocommand
noexec: Preload the dummy exec functions contained in 'noexec_file'
noexec_file: File containing dummy exec functions
ignore_local_sudoers: If LDAP directory is up, do we ignore local sudoers file
closefrom: File descriptors >= %d will be closed before executing a command
closefrom_override: If set, users may override the value of `closefrom' with the -C option
setenv: Allow users to set arbitrary environment variables
env_reset: Reset the environment to a default set of variables
env_check: Environment variables to check for sanity
env_delete: Environment variables to remove
env_keep: Environment variables to preserve
role: SELinux role to use in the new security context
type: SELinux type to use in the new security context
askpass: Path to the askpass helper program
env_file: Path to the sudo-specific environment file
sudoers_locale: Locale to use while parsing sudoers
visiblepw: Allow sudo to prompt for a password even if it would be visible
pwfeedback: Provide visual feedback at the password prompt when there is user input
fast_glob: Use faster globbing that is less accurate but does not access the filesystem
umask_override: The umask specified in sudoers will override the user's, even if it is more permissive

Execute the previous command with root privileges

$ sudo !!

Edit text with a specific user identity

$ sudo -u uggc vi ~www/index.html
//Edit the index.html file in the www directory under the home directory as the uggc user

List current permissions

sudo -l

List version information of sudo

sudo -V

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