spshed(8) spool scheduler


spshed [ options ]


spshed is the spool scheduler process for the GNUspool spooler and document management system.

To start GNUspool, spshed should be started. This should normally be done using gspl-start(1), which restarts it and passes the appropriate options. This may be put within the Operating System startup scripts.

Likewise to halt it, gspl-stop(1) should be invoked. This should be put, using the -y option, in any system shutdown routines.

If you do need to kill spshed for any reason, first try kill(1) without any -9 option. This will give spshed the opportunity to attempt to tidy up any IPC facilities before shutting down.

Information, either in respect of other machines to connect to, or pre-existing jobs and printers on the current machine, are read from the files gnuspool.hosts and the spool directory respectively.

If a networked version of GNUspool is being run, then a ``slave'' spshed process is spawned to monitor and process incoming network messages. Incoming remotely-submitted jobs and API interfaces are handled via a separate process xtnetserv(8), which is also invoked as appropriate by gspl-start(1).

Appropriate log messages are written by spshed and other system processes to a log file, spshed_reps. Be sure to check this file for any error messages relevant to any problems you encounter.


gnuspool.hosts host names and descriptions

gnuspool.conf master configuration file

int-config message file

spshed_jfile job file

spshed_pfile printer file

spshed_reps error log file

spufile0 user data

charges0 user charges data

spmm_jobi job memory-mapped hash file

spmm_jobd job memory-mapped data file

spmm_ptrs printers memory-mapped file

spmm_xfer communication buffer memory-mapped file


alternative location for spool directory.
alternative location for help file directory.
alternative location for internal programs directory.


An IPC message queue, with key 0x58691000 and owned by "spooler", is created by spshed and used to receive messages from user processes, pass instructions to spd(8), and to pass internal messages from the slave spshed process to the master.

Two shared memory segments are created to hold details of jobs and printers. As the shared memory facility provides no facilities for growth, then additional shared memory segments may be created if the job and printer lists expand sufficiently and the original ones deallocated.

The keys given to the shared memory segments start at 0x58691002 and ascend upwards to 0x58691064 before wrapping around.

A further shared memory segment, with key 0x58692002 is created to hold details of pending jobs before transfer to the main shared memory segment.

Versions of spshed may use memory-mapped files rather than shared memory. The files are held in the spool directory, by default /var/spool/gnuspool, and have the names spmm_jobi, spmm_jobd, spmm_ptrs and spmm_xfer.

A set of 5 semaphores, with the key 0x58691001 is created to interlock access to the shared memory segments.

The presence or absence of these IPC facilities is used by spshed and other programs to determine whether a previous copy of itself is running. If spshed is abnormally terminated, it will probably be necessary to delete these IPC facilities before spshed can be restarted.

When printers are set running, spshed invokes an instance of spd(8) to control each printer. Mail and attention messages are passed to spmdisp(8) for processing.


spshed accepts and sends interconnections from other machines on TCP port, passes the contents of spool files on a further TCP port, and undertakes ``probes'' on a UDP port.

The port numbers are set up in the /etc/services file when GNUspool is first installed.


spshed is invoked from system startup procedures or other programs such as gspl-start(1). Thereafter it runs as a ``daemon process'' and diagnostics are not written to any terminal but to the file spshed_reps.

In the event of any problems this file should be examined.


Copyright (c) 2009 Free Software Foundation, Inc. This is free software. You may redistribute copies of it under the terms of the GNU General Public License <http://www.gnu.org/licenses/gpl.html>. There is NO WARRANTY, to the extent permitted by law.


John M Collins, Xi Software Ltd.