# phpman > man > sudo > **TLDR:** Execute a single command as the superuser or another user. > - Run a command as the superuser: `sudo {{less /var/log/syslog}}` - Edit a file as the superuser with your default editor: `sudo {{-e|--edit}} {{/etc/fstab}}` - Run a command as another user and/or group: `sudo {{-u|--user}} {{user}} {{-g|--group}} {{group}} {{id -a}}` - Repeat the last command prefixed with `sudo` (only in Bash, Zsh, etc.): `sudo !!` - Launch the default shell with superuser privileges and run login-specific files (`.profile`, `.bash_profile`, etc.): `sudo {{-i|--login}}` - Launch the default shell with superuser privileges without changing the environment: `sudo {{-s|--shell}}` - Launch the default shell as the specified user, loading the user's environment and reading login-specific files (`.profile`, `.bash_profile`, etc.): `sudo {{-i|--login}} {{-u|--user}} {{user}}` - List the allowed (and forbidden) commands for the invoking user in longer format: `sudo {{-ll|--list --list}}` *Source: tldr-pages* --- [SUDO(8)](https://www.chedong.com/phpMan.php/man/SUDO/8/markdown) BSD System Manager's Manual [SUDO(8)](https://www.chedong.com/phpMan.php/man/SUDO/8/markdown) ## NAME **sudo**, **sudoedit** — execute a command as another user ## SYNOPSIS **sudo** **-h** | **-K** | **-k** | **-V** **sudo** **-v** [**-ABknS**] [**-g** _group_] [**-h** _host_] [**-p** _prompt_] [**-u** _user_] **sudo** **-l** [**-ABknS**] [**-g** _group_] [**-h** _host_] [**-p** _prompt_] [**-U** _user_] [**-u** _user_] [_command_] **sudo** [**-ABbEHnPS**] [**-C** _num_] [**-D** _directory_] [**-g** _group_] [**-h** _host_] [**-p** _prompt_] [**-R** _directory_] [**-r** _role_] [**-t** _type_] [**-T** _timeout_] [**-u** _user_] [_VAR_=_value_] [**-i** | **-s**] [_command_] **sudoedit** [**-ABknS**] [**-C** _num_] [**-D** _directory_] [**-g** _group_] [**-h** _host_] [**-p** _prompt_] [**-R** _directory_] [**-r** _role_] [**-t** _type_] [**-T** _timeout_] [**-u** _user_] _file_ _..._ ## DESCRIPTION **sudo** allows a permitted user to execute a _command_ as the superuser or another user, as speci‐ fied by the security policy. The invoking user's real (_not_ effective) user-ID is used to de‐ termine the user name with which to query the security policy. **sudo** supports a plugin architecture for security policies, auditing, and input/output logging. Third parties can develop and distribute their own plugins to work seamlessly with the **sudo** front-end. The default security policy is _sudoers_, which is configured via the file _/etc/sudoers_, or via LDAP. See the _Plugins_ section for more information. The security policy determines what privileges, if any, a user has to run **sudo**. The policy may require that users authenticate themselves with a password or another authentication mechanism. If authentication is required, **sudo** will exit if the user's password is not entered within a configurable time limit. This limit is policy-specific; the default password prompt timeout for the _sudoers_ security policy is 0 minutes. Security policies may support credential caching to allow the user to run **sudo** again for a pe‐ riod of time without requiring authentication. By default, the _sudoers_ policy caches creden‐ tials on a per-terminal basis for 15 minutes. See the _timestamp_type_ and _timestamp_timeout_ op‐ tions in [sudoers(5)](https://www.chedong.com/phpMan.php/man/sudoers/5/markdown) for more information. By running **sudo** with the **-v** option, a user can up‐ date the cached credentials without running a _command_. On systems where **sudo** is the primary method of gaining superuser privileges, it is imperative to avoid syntax errors in the security policy configuration files. For the default security policy, [sudoers(5)](https://www.chedong.com/phpMan.php/man/sudoers/5/markdown), changes to the configuration files should be made using the [visudo(8)](https://www.chedong.com/phpMan.php/man/visudo/8/markdown) util‐ ity which will ensure that no syntax errors are introduced. When invoked as **sudoedit**, the **-e** option (described below), is implied. Security policies and audit plugins may log successful and failed attempts to run **sudo**. If an I/O plugin is configured, the running command's input and output may be logged as well. The options are as follows: ### -A --askpass Normally, if **sudo** requires a password, it will read it from the user's terminal. If the **-A** (_askpass_) option is specified, a (possibly graphical) helper program is executed to read the user's password and output the password to the standard out‐ put. If the SUDO_ASKPASS environment variable is set, it specifies the path to the helper program. Otherwise, if [sudo.conf(5)](https://www.chedong.com/phpMan.php/man/sudo.conf/5/markdown) contains a line specifying the askpass program, that value will be used. For example: # Path to askpass helper program Path askpass /usr/X11R6/bin/ssh-askpass If no askpass program is available, **sudo** will exit with an error. ### -B --bell tion has no effect if an askpass program is used. ### -b --background Run the given command in the background. Note that it is not possible to use shell job control to manipulate background processes started by **sudo**. Most interactive commands will fail to work properly in background mode. ### -C --close-from Close all file descriptors greater than or equal to _num_ before executing a command. Values less than three are not permitted. By default, **sudo** will close all open file descriptors other than standard input, standard output, and standard error when executing a command. The security policy may restrict the user's ability to use this option. The _sudoers_ policy only permits use of the **-C** option when the ad‐ ministrator has enabled the _closefrom_override_ option. ### -D --chdir Run the command in the specified _directory_ instead of the current working direc‐ tory. The security policy may return an error if the user does not have permission to specify the working directory. ### -E --preserve-env Indicates to the security policy that the user wishes to preserve their existing environment variables. The security policy may return an error if the user does not have permission to preserve the environment. ### --preserve-env=list Indicates to the security policy that the user wishes to add the comma-separated list of environment variables to those preserved from the user's environment. The security policy may return an error if the user does not have permission to pre‐ serve the environment. This option may be specified multiple times. ### -e --edit string "sudoedit" is used when consulting the security policy. If the user is au‐ thorized by the policy, the following steps are taken: 1. Temporary copies are made of the files to be edited with the owner set to the invoking user. 2. The editor specified by the policy is run to edit the temporary files. The _sudoers_ policy uses the SUDO_EDITOR, VISUAL and EDITOR environment variables (in that order). If none of SUDO_EDITOR, VISUAL or EDITOR are set, the first program listed in the _editor_ [sudoers(5)](https://www.chedong.com/phpMan.php/man/sudoers/5/markdown) option is used. 3. If they have been modified, the temporary files are copied back to their orig‐ inal location and the temporary versions are removed. To help prevent the editing of unauthorized files, the following restrictions are enforced unless explicitly allowed by the security policy: •• Symbolic links may not be edited (version 1.8.15 and higher). •• Symbolic links along the path to be edited are not followed when the parent di‐ rectory is writable by the invoking user unless that user is root (version 1.8.16 and higher). •• Files located in a directory that is writable by the invoking user may not be edited unless that user is root (version 1.8.16 and higher). Users are never allowed to edit device special files. If the specified file does not exist, it will be created. Note that unlike most commands run by _sudo_, the editor is run with the invoking user's environment unmod‐ ified. If the temporary file becomes empty after editing, the user will be prompted before it is installed. If, for some reason, **sudo** is unable to update a file with its edited version, the user will receive a warning and the edited copy will remain in a temporary file. ### -g --group Run the command with the primary group set to _group_ instead of the primary group specified by the target user's password database entry. The _group_ may be either a group name or a numeric group-ID (GID) prefixed with the ‘#’ character (e.g., #0 for GID 0). When running a command as a GID, many shells require that the ‘#’ be escaped with a backslash (‘\’). If no **-u** option is specified, the command will be run as the invoking user. In either case, the primary group will be set to _group_. The _sudoers_ policy permits any of the target user's groups to be specified via the **-g** option as long as the **-P** option is not in use. ### -H --set-home Request that the security policy set the HOME environment variable to the home di‐ rectory specified by the target user's password database entry. Depending on the policy, this may be the default behavior. ### -h --help ### -h --host Run the command on the specified _host_ if the security policy plugin supports remote commands. Note that the _sudoers_ plugin does not currently support running remote commands. This may also be used in conjunction with the **-l** option to list a user's privileges for the remote host. ### -i --login Run the shell specified by the target user's password database entry as a login shell. This means that login-specific resource files such as _.profile_, _.bash_profile_, or _.login_ will be read by the shell. If a command is specified, it is passed to the shell as a simple command using the **-c** option. The command and any arguments are concatenated, separated by spaces, after escaping each character (including white space) with a backslash (‘\’) except for alphanumerics, under‐ scores, hyphens, and dollar signs. If no command is specified, an interactive shell is executed. **sudo** attempts to change to that user's home directory before running the shell. The command is run with an environment similar to the one a user would receive at log in. Note that most shells behave differently when a com‐ mand is specified as compared to an interactive session; consult the shell's manual for details. The _Command_ _environment_ section in the [sudoers(5)](https://www.chedong.com/phpMan.php/man/sudoers/5/markdown) manual documents how the **-i** option affects the environment in which a command is run when the _sudoers_ policy is in use. ### -K --remove-timestamp Similar to the **-k** option, except that it removes the user's cached credentials en‐ tirely and may not be used in conjunction with a command or other option. This op‐ tion does not require a password. Not all security policies support credential caching. ### -k --reset-timestamp When used without a command, invalidates the user's cached credentials. In other words, 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. When used in conjunction with a command or an option that may require a password, this option will cause **sudo** to ignore the user's cached credentials. As a result, **sudo** will prompt for a password (if one is required by the security policy) and will not update the user's cached credentials. Not all security policies support credential caching. ### -l --list voking user (or the user specified by the **-U** option) on the current host. A longer list format is used if this option is specified multiple times and the security policy supports a verbose output format. If a _command_ is specified and is permitted by the security policy, the fully-quali‐ fied path to the command is displayed along with any command line arguments. If a _command_ is specified but not allowed by the policy, **sudo** will exit with a status value of 1. ### -n --non-interactive Avoid prompting the user for input of any kind. If a password is required for the command to run, **sudo** will display an error message and exit. ### -P --preserve-groups Preserve the invoking user's group vector unaltered. By default, the _sudoers_ pol‐ icy will initialize the group vector to the list of groups the target user is a member of. The real and effective group-IDs, however, are still set to match the target user. ### -p --prompt Use a custom password prompt with optional escape sequences. The following percent (‘%’) escape sequences are supported by the _sudoers_ policy: %H expanded to the host name including the domain name (only if the machine's host name is fully qualified or the _fqdn_ option is set in [sudoers(5)](https://www.chedong.com/phpMan.php/man/sudoers/5/markdown)) %h expanded to the local host name without the domain name %p expanded to the name of the user whose password is being requested (respects the _rootpw_, _targetpw_, and _runaspw_ flags in [sudoers(5)](https://www.chedong.com/phpMan.php/man/sudoers/5/markdown)) %U expanded to the login name of the user the command will be run as (defaults to root unless the **-u** option is also specified) %u expanded to the invoking user's login name %% two consecutive ‘%’ characters are collapsed into a single ‘%’ character The custom prompt will override the default prompt specified by either the security policy or the SUDO_PROMPT environment variable. On systems that use PAM, the cus‐ tom prompt will also override the prompt specified by a PAM module unless the _passprompt_override_ flag is disabled in _sudoers_. ### -R --chroot Change to the specified root _directory_ (see [chroot(8)](https://www.chedong.com/phpMan.php/man/chroot/8/markdown)) before running the command. The security policy may return an error if the user does not have permission to specify the root directory. ### -r --role Run the command with an SELinux security context that includes the specified _role_. ### -S --stdin Write the prompt to the standard error and read the password from the standard in‐ put instead of using the terminal device. ### -s --shell Run the shell specified by the SHELL environment variable if it is set or the shell specified by the invoking user's password database entry. If a command is speci‐ fied, it is passed to the shell as a simple command using the **-c** option. The com‐ mand and any arguments are concatenated, separated by spaces, after escaping each character (including white space) with a backslash (‘\’) except for alphanumerics, underscores, hyphens, and dollar signs. If no command is specified, an interactive shell is executed. Note that most shells behave differently when a command is specified as compared to an interactive session; consult the shell's manual for de‐ tails. ### -t --type Run the command with an SELinux security context that includes the specified _type_. If no _type_ is specified, the default type is derived from the role. ### -U --other-user Used in conjunction with the **-l** option to list the privileges for _user_ instead of for the invoking user. The security policy may restrict listing other users' priv‐ ileges. The _sudoers_ policy only allows root or a user with the ALL privilege on the current host to use this option. ### -T --command-timeout Used to set a timeout for the command. If the timeout expires before the command has exited, the command will be terminated. The security policy may restrict the ability to set command timeouts. The _sudoers_ policy requires that user-specified timeouts be explicitly enabled. ### -u --user Run the command as a user other than the default target user (usually _root_). The _user_ may be either a user name or a numeric user-ID (UID) prefixed with the ‘#’ character (e.g., #0 for UID 0). When running commands as a UID, many shells re‐ quire that the ‘#’ be escaped with a backslash (‘\’). Some security policies may restrict UIDs to those listed in the password database. The _sudoers_ policy allows UIDs that are not in the password database as long as the _targetpw_ option is not set. Other security policies may not support this. ### -V --version Print the **sudo** version string as well as the version string of any configured plug‐ ins. If the invoking user is already root, the **-V** option will display the argu‐ ments passed to configure when **sudo** was built; plugins may display additional in‐ formation such as default options. ### -v --validate Update the user's cached credentials, authenticating the user if necessary. For the _sudoers_ plugin, this extends the **sudo** timeout for another 15 minutes by de‐ fault, but does not run a command. Not all security policies support cached cre‐ dentials. **--** The **--** option indicates that **sudo** should stop processing command line arguments. Options that take a value may only be specified once unless otherwise indicated in the descrip‐ tion. This is to help guard against problems caused by poorly written scripts that invoke **sudo** with user-controlled input. Environment variables to be set for the command may also be passed on the command line in the form of _VAR_=_value_, e.g., LD_LIBRARY_PATH=_/usr/local/pkg/lib_. Variables passed on the command line are subject to restrictions imposed by the security policy plugin. The _sudoers_ policy subjects variables passed on the command line to the same restrictions as normal environment variables with one important exception. If the _setenv_ option is set in _sudoers_, the command to be run has the SETENV tag set or the command matched is ALL, the user may set variables that would otherwise be forbidden. See [sudoers(5)](https://www.chedong.com/phpMan.php/man/sudoers/5/markdown) for more information. ## COMMAND EXECUTION When **sudo** executes a command, the security policy specifies the execution environment for the command. Typically, the real and effective user and group and IDs are set to match those of the target user, as specified in the password database, and the group vector is initialized based on the group database (unless the **-P** option was specified). The following parameters may be specified by security policy: •• real and effective user-ID •• real and effective group-ID •• supplementary group-IDs •• the environment list •• current working directory •• file creation mode mask (umask) •• SELinux role and type •• scheduling priority (aka nice value) ### Process model There are two distinct ways **sudo** can run a command. If an I/O logging plugin is configured or if the security policy explicitly requests it, a new pseudo-terminal (“pty”) is allocated and [fork(2)](https://www.chedong.com/phpMan.php/man/fork/2/markdown) is used to create a second **sudo** process, re‐ ferred to as the _monitor_. The _monitor_ creates a new terminal session with itself as the leader and the pty as its controlling terminal, calls [fork(2)](https://www.chedong.com/phpMan.php/man/fork/2/markdown), sets up the execution environment as described above, and then uses the [execve(2)](https://www.chedong.com/phpMan.php/man/execve/2/markdown) system call to run the command in the child process. The _monitor_ exists to relay job control signals between the user's existing terminal and the pty the command is being run in. This makes it possible to suspend and resume the com‐ mand. Without the monitor, the command would be in what POSIX terms an “orphaned process group” and it would not receive any job control signals from the kernel. When the command ex‐ its or is terminated by a signal, the _monitor_ passes the command's exit status to the main **sudo** process and exits. After receiving the command's exit status, the main **sudo** passes the com‐ mand's exit status to the security policy's close function and exits. If no pty is used, **sudo** calls [fork(2)](https://www.chedong.com/phpMan.php/man/fork/2/markdown), sets up the execution environment as described above, and uses the [execve(2)](https://www.chedong.com/phpMan.php/man/execve/2/markdown) system call to run the command in the child process. The main **sudo** process waits until the command has completed, then passes the command's exit status to the se‐ curity policy's close function and exits. As a special case, if the policy plugin does not de‐ fine a close function, **sudo** will execute the command directly instead of calling [fork(2)](https://www.chedong.com/phpMan.php/man/fork/2/markdown) first. The _sudoers_ policy plugin will only define a close function when I/O logging is enabled, a pty is required, an SELinux role is specified, the command has an associated timeout, or the _pam_session_ or _pam_setcred_ options are enabled. Note that _pam_session_ and _pam_setcred_ are en‐ abled by default on systems using PAM. On systems that use PAM, the security policy's close function is responsible for closing the PAM session. It may also log the command's exit status. ### Signal handling When the command is run as a child of the **sudo** process, **sudo** will relay signals it receives to the command. The SIGINT and SIGQUIT signals are only relayed when the command is being run in a new pty or when the signal was sent by a user process, not the kernel. This prevents the command from receiving SIGINT twice each time the user enters control-C. Some signals, such as SIGSTOP and SIGKILL, cannot be caught and thus will not be relayed to the command. As a gen‐ eral rule, SIGTSTP should be used instead of SIGSTOP when you wish to suspend a command being run by **sudo**. As a special case, **sudo** will not relay signals that were sent by the command it is running. This prevents the command from accidentally killing itself. On some systems, the [reboot(8)](https://www.chedong.com/phpMan.php/man/reboot/8/markdown) command sends SIGTERM to all non-system processes other than itself before rebooting the sys‐ tem. This prevents **sudo** from relaying the SIGTERM signal it received back to [reboot(8)](https://www.chedong.com/phpMan.php/man/reboot/8/markdown), which might then exit before the system was actually rebooted, leaving it in a half-dead state simi‐ lar to single user mode. Note, however, that this check only applies to the command run by **sudo** and not any other processes that the command may create. As a result, running a script that calls [reboot(8)](https://www.chedong.com/phpMan.php/man/reboot/8/markdown) or [shutdown(8)](https://www.chedong.com/phpMan.php/man/shutdown/8/markdown) via **sudo** may cause the system to end up in this undefined state unless the [reboot(8)](https://www.chedong.com/phpMan.php/man/reboot/8/markdown) or [shutdown(8)](https://www.chedong.com/phpMan.php/man/shutdown/8/markdown) are run using the **exec**() family of functions instead of **system**() (which interposes a shell between the command and the calling process). If no I/O logging plugins are loaded and the policy plugin has not defined a **close**() function, set a command timeout, or required that the command be run in a new pty, **sudo** may execute the command directly instead of running it as a child process. ### Plugins Plugins may be specified via Plugin directives in the [sudo.conf(5)](https://www.chedong.com/phpMan.php/man/sudo.conf/5/markdown) file. They may be loaded as dynamic shared objects (on systems that support them), or compiled directly into the **sudo** bi‐ nary. If no [sudo.conf(5)](https://www.chedong.com/phpMan.php/man/sudo.conf/5/markdown) file is present, or if it doesn't contain any Plugin lines, **sudo** will use [sudoers(5)](https://www.chedong.com/phpMan.php/man/sudoers/5/markdown) for the policy, auditing, and I/O logging plugins. See the [sudo.conf(5)](https://www.chedong.com/phpMan.php/man/sudo.conf/5/markdown) manual for details of the _/etc/sudo.conf_ file and the [sudo_plugin(5)](https://www.chedong.com/phpMan.php/man/sudoplugin/5/markdown) manual for more information about the **sudo** plugin architecture. ## EXIT VALUE Upon successful execution of a command, the exit status from **sudo** will be the exit status of the program that was executed. If the command terminated due to receipt of a signal, **sudo** will send itself the same signal that terminated the command. If the **-l** option was specified without a command, **sudo** will exit with a value of 0 if the user is allowed to run **sudo** and they authenticated successfully (as required by the security pol‐ icy). If a command is specified with the **-l** option, the exit value will only be 0 if the com‐ mand is permitted by the security policy, otherwise it will be 1. If there is an authentication failure, a configuration/permission problem, or if the given com‐ mand cannot be executed, **sudo** exits with a value of 1. In the latter case, the error string is printed to the standard error. If **sudo** cannot [stat(2)](https://www.chedong.com/phpMan.php/man/stat/2/markdown) one or more entries in the user's PATH, an error is printed to the standard error. (If the directory does not exist or if it is not really a directory, the entry is ignored and no error is printed.) This should not happen un‐ der normal circumstances. The most common reason for [stat(2)](https://www.chedong.com/phpMan.php/man/stat/2/markdown) to return “permission denied” is if you are running an automounter and one of the directories in your PATH is on a machine that is currently unreachable. ## SECURITY NOTES **sudo** tries to be safe when executing external commands. To prevent command spoofing, **sudo** checks "." and "" (both denoting current directory) last when searching for a command in the user's PATH (if one or both are in the PATH). Depending on the security policy, the user's PATH environment variable may be modified, replaced, or passed un‐ changed to the program that **sudo** executes. Users should _never_ be granted **sudo** privileges to execute files that are writable by the user or that reside in a directory that is writable by the user. If the user can modify or replace the command there is no way to limit what additional commands they can run. Please note that **sudo** will normally only log the command it explicitly runs. If a user runs a command such as sudo su or sudo sh, subsequent commands run from that shell are not subject to **sudo**'s security policy. The same is true for commands that offer shell escapes (including most editors). If I/O logging is enabled, subsequent commands will have their input and/or output logged, but there will not be traditional logs for those commands. Because of this, care must be taken when giving users access to commands via **sudo** to verify that the command does not in‐ advertently give the user an effective root shell. For information on ways to address this, please see the _Preventing_ _shell_ _escapes_ section in [sudoers(5)](https://www.chedong.com/phpMan.php/man/sudoers/5/markdown). To prevent the disclosure of potentially sensitive information, **sudo** disables core dumps by de‐ fault while it is executing (they are re-enabled for the command that is run). This historical practice dates from a time when most operating systems allowed set-user-ID processes to dump core by default. To aid in debugging **sudo** crashes, you may wish to re-enable core dumps by setting “disable_coredump” to false in the [sudo.conf(5)](https://www.chedong.com/phpMan.php/man/sudo.conf/5/markdown) file as follows: Set disable_coredump false See the [sudo.conf(5)](https://www.chedong.com/phpMan.php/man/sudo.conf/5/markdown) manual for more information. ## ENVIRONMENT **sudo** utilizes the following environment variables. The security policy has control over the actual content of the command's environment. EDITOR Default editor to use in **-e** (sudoedit) mode if neither SUDO_EDITOR nor VISUAL is set. MAIL Set to the mail spool of the target user when the **-i** option is specified, or when _env_reset_ is enabled in _sudoers_ (unless MAIL is present in the _env_keep_ list). HOME Set to the home directory of the target user when the **-i** or **-H** options are specified, when the **-s** option is specified and _set_home_ is set in _sudoers_, when _always_set_home_ is enabled in _sudoers_, or when _env_reset_ is enabled in _sudoers_ and _HOME_ is not present in the _env_keep_ list. LOGNAME Set to the login name of the target user when the **-i** option is specified, when the _set_logname_ option is enabled in _sudoers_, or when the _env_reset_ option is enabled in _sudoers_ (unless LOGNAME is present in the _env_keep_ list). PATH May be overridden by the security policy. SHELL Used to determine shell to run with **-s** option. SUDO_ASKPASS Specifies the path to a helper program used to read the password if no termi‐ nal is available or if the **-A** option is specified. SUDO_COMMAND Set to the command run by sudo, including command line arguments. The command line arguments are truncated at 4096 characters to prevent a potential execu‐ tion error. SUDO_EDITOR Default editor to use in **-e** (sudoedit) mode. SUDO_GID Set to the group-ID of the user who invoked sudo. SUDO_PROMPT Used as the default password prompt unless the **-p** option was specified. SUDO_PS1 If set, PS1 will be set to its value for the program being run. SUDO_UID Set to the user-ID of the user who invoked sudo. SUDO_USER Set to the login name of the user who invoked sudo. USER Set to the same value as LOGNAME, described above. VISUAL Default editor to use in **-e** (sudoedit) mode if SUDO_EDITOR is not set. ## FILES /etc/sudo.conf **sudo** front-end configuration ## EXAMPLES Note: the following examples assume a properly configured security policy. To get a file listing of an unreadable directory: $ sudo ls /usr/local/protected To list the home directory of user yaz on a machine where the file system holding ~yaz is not exported as root: $ sudo -u yaz ls ~yaz To edit the _index.html_ file as user www: $ sudoedit -u www ~www/htdocs/index.html To view system logs only accessible to root and users in the adm group: $ sudo -g adm more /var/log/syslog To run an editor as jim with a different primary group: $ sudoedit -u jim -g audio ~jim/sound.txt To shut down a machine: $ sudo shutdown -r +15 "quick reboot" To make a usage listing of the directories in the /home partition. Note that this runs the commands in a sub-shell to make the cd and file redirection work. $ sudo sh -c "cd /home ; du -s * | sort -rn > USAGE" ## DIAGNOSTICS Error messages produced by **sudo** include: editing files in a writable directory is not permitted By default, **sudoedit** does not permit editing a file when any of the parent directories are writable by the invoking user. This avoids a race condition that could allow the user to overwrite an arbitrary file. See the _sudoedit_checkdir_ option in [sudoers(5)](https://www.chedong.com/phpMan.php/man/sudoers/5/markdown) for more information. editing symbolic links is not permitted By default, **sudoedit** does not follow symbolic links when opening files. See the _sudoedit_follow_ option in [sudoers(5)](https://www.chedong.com/phpMan.php/man/sudoers/5/markdown) for more information. effective uid is not 0, is sudo installed setuid root? **sudo** was not run with root privileges. The **sudo** binary must be owned by the root user and have the set-user-ID bit set. Also, it must not be located on a file system mounted with the ‘nosuid’ option or on an NFS file system that maps uid 0 to an unprivileged uid. effective uid is not 0, is sudo on a file system with the 'nosuid' option set or an NFS file system without root privileges? **sudo** was not run with root privileges. The **sudo** binary has the proper owner and permis‐ sions but it still did not run with root privileges. The most common reason for this is that the file system the **sudo** binary is located on is mounted with the ‘nosuid’ option or it is an NFS file system that maps uid 0 to an unprivileged uid. fatal error, unable to load plugins An error occurred while loading or initializing the plugins specified in [sudo.conf(5)](https://www.chedong.com/phpMan.php/man/sudo.conf/5/markdown). invalid environment variable name One or more environment variable names specified via the **-E** option contained an equal sign (‘=’). The arguments to the **-E** option should be environment variable names without an associated value. no password was provided When **sudo** tried to read the password, it did not receive any characters. This may happen if no terminal is available (or the **-S** option is specified) and the standard input has been redirected from _/dev/null_. a terminal is required to read the password **sudo** needs to read the password but there is no mechanism available for it to do so. A terminal is not present to read the password from, **sudo** has not been configured to read from the standard input, the **-S** option was not used, and no askpass helper has been spec‐ ified either via the [sudo.conf(5)](https://www.chedong.com/phpMan.php/man/sudo.conf/5/markdown) file or the SUDO_ASKPASS environment variable. no writable temporary directory found **sudoedit** was unable to find a usable temporary directory in which to store its intermedi‐ ate files. The “no new privileges” flag is set, which prevents sudo from running as root. **sudo** was run by a process that has the Linux “no new privileges” flag is set. This causes the set-user-ID bit to be ignored when running an executable, which will prevent **sudo** from functioning. The most likely cause for this is running **sudo** within a container that sets this flag. Check the documentation to see if it is possible to configure the container such that the flag is not set. sudo must be owned by uid 0 and have the setuid bit set **sudo** was not run with root privileges. The **sudo** binary does not have the correct owner or permissions. It must be owned by the root user and have the set-user-ID bit set. sudoedit is not supported on this platform It is only possible to run **sudoedit** on systems that support setting the effective user- ID. timed out reading password The user did not enter a password before the password timeout (5 minutes by default) ex‐ pired. you do not exist in the passwd database Your user-ID does not appear in the system passwd database. you may not specify environment variables in edit mode It is only possible to specify environment variables when running a command. When edit‐ ing a file, the editor is run with the user's environment unmodified. ## SEE ALSO [su(1)](https://www.chedong.com/phpMan.php/man/su/1/markdown), [stat(2)](https://www.chedong.com/phpMan.php/man/stat/2/markdown), [login_cap(3)](https://www.chedong.com/phpMan.php/man/logincap/3/markdown), [passwd(5)](https://www.chedong.com/phpMan.php/man/passwd/5/markdown), [sudo.conf(5)](https://www.chedong.com/phpMan.php/man/sudo.conf/5/markdown), [sudo_plugin(5)](https://www.chedong.com/phpMan.php/man/sudoplugin/5/markdown), [sudoers(5)](https://www.chedong.com/phpMan.php/man/sudoers/5/markdown), [sudoers_timestamp(5)](https://www.chedong.com/phpMan.php/man/sudoerstimestamp/5/markdown), [sudoreplay(8)](https://www.chedong.com/phpMan.php/man/sudoreplay/8/markdown), [visudo(8)](https://www.chedong.com/phpMan.php/man/visudo/8/markdown) ## HISTORY See the HISTORY file in the **sudo** distribution () for a brief history of sudo. ## AUTHORS Many people have worked on **sudo** over the years; this version consists of code written primarily by: Todd C. Miller See the CONTRIBUTORS file in the **sudo** distribution () for an exhaustive list of people who have contributed to **sudo**. ## CAVEATS There is no easy way to prevent a user from gaining a root shell if that user is allowed to run arbitrary commands via **sudo**. Also, many programs (such as editors) allow the user to run com‐ mands via shell escapes, thus avoiding **sudo**'s checks. However, on most systems it is possible to prevent shell escapes with the [sudoers(5)](https://www.chedong.com/phpMan.php/man/sudoers/5/markdown) plugin's _noexec_ functionality. It is not meaningful to run the cd command directly via sudo, e.g., $ sudo cd /usr/local/protected since when the command exits the parent process (your shell) will still be the same. Please see the _EXAMPLES_ section for more information. Running shell scripts via **sudo** can expose the same kernel bugs that make set-user-ID shell scripts unsafe on some operating systems (if your OS has a /dev/fd/ directory, set-user-ID shell scripts are generally safe). ## BUGS If you feel you have found a bug in **sudo**, please submit a bug report at ## SUPPORT Limited free support is available via the sudo-users mailing list, see to subscribe or search the archives. ## DISCLAIMER **sudo** is provided “AS IS” and any express or implied warranties, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose are disclaimed. See the LICENSE file distributed with **sudo** or for complete de‐ tails. ## Sudo 1.9.9 January 19, 2022 Sudo 1.9.9