6.7. pam_exec - call an external command
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## 6.7. pam_exec - call an external command

`pam_exec.so` [ debug ] [ expose_authtok ] [ seteuid ] [ quiet ] [ stdout ] [ log=`file` ] [ type=`type` ] `command` [ `...` ]

### 6.7.1. DESCRIPTION

pam_exec is a PAM module that can be used to run an external command.

The child's environment is set to the current PAM environment list, as returned by pam_getenvlist(3) In addition, the following PAM items are exported as environment variables: PAM_RHOST, PAM_RUSER, PAM_SERVICE, PAM_TTY, PAM_USER and PAM_TYPE, which contains one of the module types: `account`, `auth`, `password`, `open_session` and `close_session`.

Commands called by pam_exec need to be aware of that the user can have controll over the environment.

### 6.7.2. OPTIONS

`debug`

  Print debug information.

`expose_authtok`

  During authentication the calling command can read the password from stdin(3). Only first PAM_MAX_RESP_SIZE bytes of a password are provided to the command.

`log=`file``

  The output of the command is appended to `file`

`type=`type``

  Only run the command if the module type matches the given type.

`stdout`

  Per default the output of the executed command is written to `/dev/null`. With this option, the stdout output of the executed command is redirected to the calling application. It's in the responsibility of this application what happens with the output. The `log` option is ignored.

`quiet`

  Per default pam_exec.so will echo the exit status of the external command if it fails. Specifying this option will suppress the message.

`seteuid`

  Per default pam_exec.so will execute the external command with the real user ID of the calling process. Specifying this option means the command is run with the effective user ID.

### 6.7.3. MODULE TYPES PROVIDED

All module types (`auth`, `account`, `password` and `session`) are provided.

### 6.7.4. RETURN VALUES

PAM_SUCCESS

  The external command was run successfully.

PAM_SERVICE_ERR

  No argument or a wrong number of arguments were given.

PAM_SYSTEM_ERR

  A system error occurred or the command to execute failed.

PAM_IGNORE

  `pam_setcred` was called, which does not execute the command. Or, the value given for the type= parameter did not match the module type.

### 6.7.5. EXAMPLES

Add the following line to `/etc/pam.d/passwd` to rebuild the NIS database after each local password change:

            password optional pam_exec.so seteuid /usr/bin/make -C /var/yp

This will execute the command

    make -C /var/yp

with effective user ID.

### 6.7.6. AUTHOR

pam_exec was written by Thorsten Kukuk <kukuk@thkukuk.de> and Josh Triplett <josh@joshtriplett.org>.

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