# start-stop-daemon

## NAME



           start-stop-daemon - start and stop system daemon programs
    


## SYNOPSIS



           **start-stop-daemon**[_option_...] _command_
    


## DESCRIPTION



           **start-stop-daemon** is used to control the creation and termination
           of system-level processes.  Using one of the matching options,
           **start-stop-daemon** can be configured to find existing instances of
           a running process.
    
           **Note** : Unless **--pid** or **--pidfile** are specified, **start-stop-daemon**
           behaves similar to killall(1).  **start-stop-daemon** will scan the
           process table looking for any processes which match the process
           name, parent pid, uid, and/or gid (if specified).  Any matching
           process will prevent **--start** from starting the daemon.  All
           matching processes will be sent the TERM signal (or the one
           specified via **--signal** or **--retry**) if **--stop** is specified.  For
           daemons which have long-lived children which need to live through
           a **--stop** , you must specify a pidfile.
    


## COMMANDS



           **-S** , **--start**[**--**] _arguments_
               Check for the existence of a specified process.  If such a
               process exists, **start-stop-daemon** does nothing, and exits with
               error status 1 (0 if **--oknodo** is specified).  If such a
               process does not exist, it starts an instance, using either
               the executable specified by **--exec** or, if specified, by
               **--startas**.  Any arguments given after **--** on the command line
               are passed unmodified to the program being started.
    
           **-K** , **--stop**
               Checks for the existence of a specified process.  If such a
               process exists, **start-stop-daemon** sends it the signal
               specified by **--signal** , and exits with error status 0.  If such
               a process does not exist, **start-stop-daemon** exits with error
               status 1 (0 if **--oknodo** is specified).  If **--retry** is
               specified, then **start-stop-daemon** will check that the
               process(es) have terminated.
    
           **-T** , **--status**
               Check for the existence of a specified process, and returns an
               exit status code, according to the LSB Init Script Actions
               (since version 1.16.1).
    
           **-H** , **--help**
               Show usage information and exit.
    
           **-V** , **--version**
               Show the program version and exit.
    


## OPTIONS



       **Matching options**
           **--pid** _pid_
               Check for a process with the specified _pid_ (since version
               1.17.6).  The _pid_ must be a number greater than 0.
    
           **--ppid** _ppid_
               Check for a process with the specified parent pid _ppid_ (since
               version 1.17.7).  The _ppid_ must be a number greater than 0.
    
           **-p** , **--pidfile** _pidfile_
               Check whether a process has created the file _pidfile_.
    
               **Note** : Using this matching option alone might cause unintended
               processes to be acted on, if the old process terminated
               without being able to remove the _pidfile_.
    
               **Warning** : Using this match option with a world-writable pidfile
               or using it alone with a daemon that writes the pidfile as an
               unprivileged (non-root) user will be refused with an error
               (since version 1.19.3) as this is a security risk, because
               either any user can write to it, or if the daemon gets
               compromised, the contents of the pidfile cannot be trusted,
               and then a privileged runner (such as an init script executed
               as root) would end up acting on any system process.  Using
               _/dev/null_ is exempt from these checks.
    
           **-x** , **--exec** _executable_
               Check for processes that are instances of this _executable_.
               The _executable_ argument should be an absolute pathname.
    
               **Note** : This might not work as intended with interpreted
               scripts, as the executable will point to the interpreter.
               Take into account processes running from inside a chroot will
               also be matched, so other match restrictions might be needed.
    
           **-n** , **--name** _process-name_
               Check for processes with the name _process-name_.  The _process-_
               _name_ is usually the process filename, but it could have been
               changed by the process itself.
    
               **Note** : On most systems this information is retrieved from the
               process comm name from the kernel, which tends to have a
               relatively short length limit (assuming more than 15
               characters is non-portable).
    
           **-u** , **--user** _username_ |_uid_
               Check for processes owned by the user specified by _username_ or
               _uid_.
    
               **Note** : Using this matching option alone will cause all
               processes matching the user to be acted on.
    
       **Generic options**
           **-g** , **--group** _group_ |_gid_
               Change to _group_ or _gid_ when starting the process.
    
           **-s** , **--signal** _signal_
               With **--stop** , specifies the signal to send to processes being
               stopped (default TERM).
    
           **-R** , **--retry** _timeout_ |_schedule_
               With **--stop** , specifies that **start-stop-daemon** is to check
               whether the process(es) do finish.  It will check repeatedly
               whether any matching processes are running, until none are.
               If the processes do not exit it will then take further action
               as determined by the schedule.
    
               If _timeout_ is specified instead of _schedule_ , then the schedule
               _signal_**/**_timeout_**/KILL/**_timeout_ is used, where _signal_ is the
               signal specified with **--signal**.
    
               _schedule_ is a list of at least two items separated by slashes
               (**/**); each item may be **-**_signal-number_ or [**-**]_signal-name_ , which
               means to send that signal, or _timeout_ , which means to wait
               that many seconds for processes to exit, or **forever** , which
               means to repeat the rest of the schedule forever if necessary.
    
               If the end of the schedule is reached and **forever** is not
               specified, then **start-stop-daemon** exits with error status 2.
               If a schedule is specified, then any signal specified with
               **--signal** is ignored.
    
           **-a** , **--startas** _pathname_
               With **--start** , start the process specified by _pathname_.  If not
               specified, defaults to the argument given to **--exec**.
    
           **-t** , **--test**
               Print actions that would be taken and set appropriate return
               value, but take no action.
    
           **-o** , **--oknodo**
               Return exit status 0 instead of 1 if no actions are (would be)
               taken.
    
           **-q** , **--quiet**
               Do not print informational messages; only display error
               messages.
    
           **-c** , **--chuid** _username_ |_uid_[**:**_group_ |_gid_]
               Change to this username/uid before starting the process.  You
               can also specify a group by appending a **:** , then the group or
               gid in the same way as you would for the chown(1) command
               (_user_**:**_group_).  If a user is specified without a group, the
               primary GID for that user is used.  When using this option you
               must realize that the primary and supplemental groups are set
               as well, even if the **--group** option is not specified.  The
               **--group** option is only for groups that the user isn't normally
               a member of (like adding per process group membership for
               generic users like **nobody**).
    
           **-r** , **--chroot** _root_
               Change directory and chroot to _root_ before starting the
               process.  Please note that the pidfile is also written after
               the chroot.
    
           **-d** , **--chdir** _path_
               Change directory to _path_ before starting the process.  This is
               done after the chroot if the **-r** |**--chroot** option is set.  When
               not specified, **start-stop-daemon** will change directory to the
               root directory before starting the process.
    
           **-b** , **--background**
               Typically used with programs that don't detach on their own.
               This option will force **start-stop-daemon** to fork before
               starting the process, and force it into the background.
    
               **Warning** : **start-stop-daemon** cannot check the exit status if the
               process fails to execute for **any** reason.  This is a last
               resort, and is only meant for programs that either make no
               sense forking on their own, or where it's not feasible to add
               the code for them to do this themselves.
    
           **--notify-await**
               Wait for the background process to send a readiness
               notification before considering the service started (since
               version 1.19.3).  This implements parts of the systemd
               readiness protocol, as specified in the sd_notify(3) manual
               page.  The following variables are supported:
    
               **READY=1**
                   The program is ready to give service, so we can exit
                   safely.
    
               **EXTEND_TIMEOUT_USEC=**_number_
                   The program requests to extend the timeout by _number_
                   microseconds.  This will reset the current timeout to the
                   specified value.
    
               **ERRNO=**_number_
                   The program is exiting with an error.  Do the same and
                   print the user-friendly string for the **errno** value.
    
           **--notify-timeout** _timeout_
               Set a timeout for the **--notify-await** option (since version
               1.19.3).  When the timeout is reached, **start-stop-daemon** will
               exit with an error code, and no readiness notification will be
               awaited.  The default is **60** seconds.
    
           **-C** , **--no-close**
               Do not close any file descriptor when forcing the daemon into
               the background (since version 1.16.5).  Used for debugging
               purposes to see the process output, or to redirect file
               descriptors to log the process output.  Only relevant when
               using **--background**.
    
           **-O** , **--output** _pathname_
               Redirect **stdout** and **stderr** to _pathname_ when forcing the daemon
               into the background (since version 1.20.6).  Only relevant
               when using **--background**.
    
           **-N** , **--nicelevel** _int_
               This alters the priority of the process before starting it.
    
           **-P** , **--procsched** _policy_**:**_priority_
               This alters the process scheduler policy and priority of the
               process before starting it (since version 1.15.0).  The
               priority can be optionally specified by appending a **:** followed
               by the value.  The default _priority_ is 0.  The currently
               supported policy values are **other** , **fifo** and **rr**.
    
               This option might do nothing on some systems, where POSIX
               process scheduling is not supported.
    
           **-I** , **--iosched** _class_**:**_priority_
               This alters the IO scheduler class and priority of the process
               before starting it (since version 1.15.0).  The priority can
               be optionally specified by appending a **:** followed by the
               value.  The default _priority_ is 4, unless _class_ is **idle** , then
               _priority_ will always be 7.  The currently supported values for
               _class_ are **idle** , **best-effort** and **real-time**.
    
               This option might do nothing on some systems, where Linux IO
               scheduling is not supported.
    
           **-k** , **--umask** _mask_
               This sets the umask of the process before starting it (since
               version 1.13.22).
    
           **-m** , **--make-pidfile**
               Used when starting a program that does not create its own pid
               file.  This option will make **start-stop-daemon** create the file
               referenced with **--pidfile** and place the pid into it just
               before executing the process.  Note, the file will only be
               removed when stopping the program if **--remove-pidfile** is used.
    
               **Note** : This feature may not work in all cases.  Most notably
               when the program being executed forks from its main process.
               Because of this, it is usually only useful when combined with
               the **--background** option.
    
           **--remove-pidfile**
               Used when stopping a program that does not remove its own pid
               file (since version 1.17.19).  This option will make **start-**
               **stop-daemon** remove the file referenced with **--pidfile** after
               terminating the process.
    
           **-v** , **--verbose**
               Print verbose informational messages.
    


## EXIT STATUS



           **0** The requested action was performed.  If **--oknodo** was
               specified, it's also possible that nothing had to be done.
               This can happen when **--start** was specified and a matching
               process was already running, or when **--stop** was specified and
               there were no matching processes.
    
           **1** If **--oknodo** was not specified and nothing was done.
    
           **2** If **--stop** and **--retry** were specified, but the end of the
               schedule was reached and the processes were still running.
    
           **3** Any other error.
    
           When using the **--status** command, the following status codes are
           returned:
    
           **0** Program is running.
    
           **1** Program is not running and the pid file exists.
    
           **3** Program is not running.
    
           **4** Unable to determine program status.
    


## EXAMPLE



           Start the **food** daemon, unless one is already running (a process
           named food, running as user food, with pid in food.pid):
    
            start-stop-daemon --start --oknodo --user food --name food \
              --pidfile /usr/local/var/run/food.pid --startas /usr/sbin/food \
              --chuid food -- --daemon
    
           Send **SIGTERM** to **food** and wait up to 5 seconds for it to stop:
    
            start-stop-daemon --stop --oknodo --user food --name food \
              --pidfile /usr/local/var/run/food.pid --retry 5
    
           Demonstration of a custom schedule for stopping **food** :
    
            start-stop-daemon --stop --oknodo --user food --name food \
              --pidfile /usr/local/var/run/food.pid --retry=TERM/30/KILL/5
    


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