# man > pkexec(1) > **TLDR:** Execute commands as another user. > - Run command as root: `pkexec {{command}}` - Switch user to root: `pkexec` - Run command as a specific user: `pkexec --user {{username}} {{command}}` *Source: tldr-pages* --- [_PKEXEC_(1)](https://www.chedong.com/phpMan.php/man/PKEXEC/1/markdown) pkexec [_PKEXEC_(1)](https://www.chedong.com/phpMan.php/man/PKEXEC/1/markdown) ## NAME pkexec - Execute a command as another user ## SYNOPSIS **pkexec **[**--version**] [**--disable-internal-agent**] [**--help**] **pkexec **[**--keep-cwd**] [**--user _**username_] _PROGRAM_ [_ARGUMENTS_...] ## DESCRIPTION **pkexec **allows an authorized user to execute _PROGRAM_ as another user. If _PROGRAM_ is not specified, the default shell will be run. If _username_ is not specified, then the program will be executed as the administrative super user, _root_. ## RETURN VALUE Upon successful completion, the return value is the return value of _PROGRAM_. If the calling process is not authorized or an authorization could not be obtained through authentication or an error occured, **pkexec **exits with a return value of 127. If the authorization could not be obtained because the user dismissed the authentication dialog, **pkexec **exits with a return value of 126. ## AUTHENTICATION AGENT **pkexec**, like any other polkit application, will use the authentication agent registered for the calling process or session. However, if no authentication agent is available, then **pkexec** will register its own textual authentication agent. This behavior can be turned off by passing the **--disable-internal-agent **option. ## SECURITY NOTES Executing a program as another user is a privileged operation. By default the action to check for (see the section called “ACTION AND AUTHORIZATIONS”) requires administrator authentication. In addition, the authentication dialog presented to the user will display the full path to the program to be executed so the user is aware of what will happen. The environment that _PROGRAM_ will run it, will be set to a minimal known and safe environment in order to avoid injecting code through LD_LIBRARY_PATH or similar mechanisms. In addition the PKEXEC_UID environment variable is set to the user id of the process invoking **pkexec**. As a result, **pkexec **will not by default allow you to run X11 applications as another user since the $DISPLAY and $XAUTHORITY environment variables are not set. These two variables will be retained if the _org.freedesktop.policykit.exec.allow_gui_ annotation on an action is set to a nonempty value; this is discouraged, though, and should only be used for legacy programs. **pkexec **will run _PROGRAM_ in _username_'s home directory, unless **--keep-cwd **is used to override this behavior Note that **pkexec **does no validation of the _ARGUMENTS_ passed to _PROGRAM_. In the normal case (where administrator authentication is required every time **pkexec **is used), this is not a problem since if the user is an administrator he might as well just run **pkexec bash **to get root. However, if an action is used for which the user can retain authorization (or if the user is implicitly authorized) this could be a security hole. Therefore, as a rule of thumb, programs for which the default required authorization is changed, should **never **implicitly trust user input (e.g. like any other well-written _suid_ program). ## ACTION AND AUTHORIZATIONS By default, the _org.freedesktop.policykit.exec_ action is used. To use another action, use the _org.freedesktop.policykit.exec.path_ annotation on an action with the value set to the full path of the program. In addition to specifying the program, the authentication message, description, icon and defaults can be specified. If the _org.freedesktop.policykit.exec.argv1_ annotation is present, the action will only be picked if the first argument to the program matches the value of the annotation. Note that authentication messages may reference variables (see the section called “VARIABLES”), for example $(user) will be expanded to the value of the user variable. ## WRAPPER USAGE To avoid modifying existing software to prefix their command-line invocations with **pkexec**, it's possible to use **pkexec **in a **she-bang wrapper**[1] like this: #!/usr/bin/pkexec /usr/bin/python import os import sys print "Hello, I'm running as uid %d"%(os.getuid()) for n in range(len(sys.argv)): print "arg[%d]=`%s'"%(n, sys.argv[n]) If this script is installed into /usr/bin/my-pk-test, then the following annotations [...] /usr/bin/python /usr/bin/my-pk-test [...] can be used to select the appropriate polkit action. Be careful to get the latter annotation right, otherwise it will match any **pkexec **invocation of /usr/bin/python scripts. ## VARIABLES The following variables are set by **pkexec**. They can be used in authorization rules and messages shown in authentication dialogs: _program_ Fully qualified path to the program to be executed. Example: “/bin/cat” _command_line_ The requested command-line (do not use this for any security checks, it is not secure). Example: “cat /srv/xyz/foobar” _user_ The user name of the user to execute the program as. Example: “davidz” _user.gecos_ The full name of the user to execute the program as. Example: “David Zeuthen” _user.display_ A representation of the user to execute the program as that is suitable for display in an authentication dialog. Is typically set to a combination of the user name and the full name. Example: “David Zeuthen (davidz)” ## AUTHOR Written by David Zeuthen <> with a lot of help from many others. ## BUGS Please send bug reports to either the distribution or the polkit-devel mailing list, see the link ** **on how to subscribe. ## SEE ALSO [**polkit**(8)](https://www.chedong.com/phpMan.php/man/polkit/8/markdown), [**polkitd**(8)](https://www.chedong.com/phpMan.php/man/polkitd/8/markdown), [**pkaction**(1)](https://www.chedong.com/phpMan.php/man/pkaction/1/markdown), [**pkcheck**(1)](https://www.chedong.com/phpMan.php/man/pkcheck/1/markdown), [**pkttyagent**(1)](https://www.chedong.com/phpMan.php/man/pkttyagent/1/markdown) ## NOTES 1. she-bang wrapper (Unix) polkit May 2009 [_PKEXEC_(1)](https://www.chedong.com/phpMan.php/man/PKEXEC/1/markdown)