NAME

       daemonize - run a program as a Unix daemon

SYNOPSIS

       daemonize [-a] [-c directory] [-e stderr] [-o stdout] [-p pidfile] [-l lockfile] [-u user]
       [-v] path [arg] ...

DESCRIPTION

       daemonize runs a command as a Unix daemon.  As defined in W. Richard Stevens'  1990  book,
       Unix  Network Programming (Addison-Wesley, 1990), a daemon is “a process that executes `in
       the background' (i.e., without an associated terminal or login shell) either  waiting  for
       some  event to occur, or waiting to perform some specified task on a periodic basis.” Upon
       startup, a typical daemon program will:

       o Close all open file descriptors (especially standard input, standard output and standard
         error)

       o Change  its  working  directory to the root filesystem, to ensure that it doesn't tie up
         another filesystem and prevent it from being unmounted

       o Reset its umask value

       o Run in the background (i.e., fork)

       o Disassociate from its process group (usually a shell), to insulate itself  from  signals
         (such as HUP) sent to the process group

       o Ignore all terminal I/O signals

       o Disassociate from the control terminal (and take steps not to reacquire one)

       o Handle any SIGCLD signals

       Most programs that are designed to be run as daemons do that work for themselves. However,
       you'll occasionally run across one that does not.  When you must run a daemon program that
       does  not  properly make itself into a true Unix daemon, you can use daemonize to force it
       to run as a true daemon.

OPTIONS

       -a     Append to the output files, rather than overwriting them (which  is  the  default).
              Only applicable if -e and/or -o are specified.

       -c directory
              Specifies the directory to which to change before running the program.  Defaults to
              "/". The choice for this option  is  important.  The  file  system  containing  the
              daemon's  working directory cannot be unmounted while the daemon is running. That's
              why most daemons are careful to use a working directory on the root file system.

       -e stderr
              Redirect standard error to the specified file, instead of "/dev/null".

              Warning: Be careful where you redirect the output! The file system  containing  the
              open  file  cannot be unmounted as long as the file is open. For best results, make
              sure that this output file is on the same  file  system  as  the  daemon's  working
              directory. (See the -c option.)

       -E name=value
              Add  an  environment variable to the environment the daemon will see. The parameter
              must be of the form name=value.  This parameter may be specified multiple times.

       -o stdout
              Redirect standard output to the specified file, instead of "/dev/null".

              Warning: Be careful where you redirect the output! The file system  containing  the
              open  file  cannot be unmounted as long as the file is open. For best results, make
              sure that this output file is on the same  file  system  as  the  daemon's  working
              directory. (See the -c option.)

       -p pidfile
              Causes daemonize to write the numeric process ID (PID) of the running daemon to the
              specified file. This option is useful when the  program  being  daemonized  doesn't
              create its own PID file.

       -l lockfile
              Single-instance checking. Causes daemonize to ensure that no more than one instance
              of the daemon is running by placing an exclusive lock on given lockfile. If another
              process already has a lock on the lockfile, daemonize exits.

       It  is  possible  to  use  the  pidfile  as  the  lock  file  (e.g.,  "-p  /var/run/foo -l
       /var/run/foo"), though typical daemons use separate files.

       NOTE: If the executed program decides to close all file descriptors,  the  single-instance
       locking  will  not work, since the lock depends on an open file descriptor. (The operating
       system kernel removes the lock once the process  holding  the  lock  closes  the  file  or
       exits.)   Normal  processes that do not daemonize themselves do not usually close all file
       descriptors.

       -u user
              Run the program as the specified user. This  option  only  works  if  daemonize  is
              invoked  by  the  superuser.   Note:  For  obvious  reasons, it's very dangerous to
              install daemonize as a setuid-to-root executable. For that reason,  daemonize  will
              refuse to run if it detects that it has been installed that way.

       -v     Cause  daemonize  to  write  verbose  messages to standard error, telling what it's
              doing as it daemonizes the program.

NOTES

       If the host operating system provides the daemon(3) library routine,  daemonize  will  use
       it.  Otherwise,  daemonize  uses  its  own  version  of daemon(3).  This choice is made at
       compile time. (BSD 4.4-derived operating systems  tend  to  provide  their  own  daemon(3)
       routine.)

       FreeBSD  5.0  introduced a daemon(1) command that is similar to, but less functional, than
       daemonize.

LICENSE

       This program released under a BSD-style license. For more  details,  consult  the  LICENSE
       file        accompanying        the        source       distribution,       or       visit
       "http://software.clapper.org/daemonize/LICENSE".

SEE ALSO

       daemon(3), setsid(2), flock(2)

       daemonize Home Page: http://software.clapper.org/daemonize/

AUTHOR

       Brian M. Clapper, bmc <at> clapper <dot> org

CONTRIBUTORS

       Support for the -e and -o options is based on a patch submitted by Tim Starling (tstarling
       <at> wikimedia <dot> org).

       Support  for  the  -l  option  is based on a patch submitted by Yakov Lerner (iler.ml <at>
       gmail <dot> com).