procServ man page

procServ — Process Server with Telnet Console and Log Access


procServ [Options] port command args...


procServ(1) creates a run time environment for a command (e.g. a soft IOC). It forks a server run as a daemon into the background, which creates a child process running command with all remaining args from the command line. The server provides console access (stdin/stdout) to the child process by offering a telnet connection at the specified port. For security reasons, by default access is restricted to connections from localhost (, so that logging into a valid account on the host machine is required.

procServ can be configured to write a console log of all in- and output of the child process into a file using the -L (--logfile) option. Sending the signal SIGHUP to the server will make it reopen the log file. To facilitate running under a central console access management (like conserver), the -l (--logport) option creates an additional telnet port, which is by default public (i.e. not restricted to localhost), and provides read-only log access to the child’s console. The -r (--restrict) option restricts the log port to localhost, similar to the access port.

Both access and log ports allow multiple connections, which are handled transparently: all input from access connections is forwarded to the child process, all output from the child is forwarded to all access and log connections (and written to the log file). All diagnostic messages from the server process start with "@@@ " to be clearly distinguished from child process messages. A name specified by the -n (--name) option will replace the command string in many messages for increased readability.

The server will by default automatically respawn the child process when it dies. To avoid spinning, a minimum time between child process restarts is honoured (default: 15 seconds, can be changed using the --holdoff option). This behaviour can be toggled online using the toggle command ^T, the default may be changed using the --noautorestart option. You can restart a running child manually by sending a signal to the child process using the kill command ^X. With the child process being shut down, the server accepts two commands: ^R or ^X to restart the child, and ^Q to quit the server. The -w (--wait) option starts the server in this shut down mode, waiting for a telnet connection to issue a manual start command to create the child.

Any telnet connection (control or log) can be disconnected using the client’s disconnect sequence. Control connections can also be disconnected by sending the logout command character, that can be specified using the -x (--logoutcmd) option.

To block input characters that are potentially dangerous to the child (e.g. ^D and ^C on soft IOCs), the -i (--ignore) option can be used to specify characters that are silently ignored when coming from a console access port.

To facilitate being started and stopped as a standard system service, the -p (--pidfile) option tells the server to create a standard PID file containing the PID of the server process.

The -d (--debug) option runs the server in debug mode: the daemon process stays in the foreground, printing all regular log content plus additional debug messages to stdout.


Allow control connections from anywhere. (Default: restrict control access to localhost.) Creates a serious security hole, as telnet clients from anywhere can connect to the child’s stdin/stdout and execute arbitrary commands on the host, if the child permits. Needs to be enabled at compile-time (see Makefile). Please do not enable and use this option unless you exactly know why and what you are doing.
Toggle auto restart flag when char is sent on an access connection. Use ^ to specify a control character, "" to disable. Default is ^T.
Set the maximum size of core file. See getrlimit(2) documentation for details. Setting size to 0 will keep child from creating core files.
-c, --chdir=dir
Change directory to dir before starting child. This is done each time the child is started to make sure symbolic links are resolved on child restart.
-d, --debug
Enter debug mode. Debug mode will keep the server process in the foreground and enables diagnostic messages that will be sent to the controlling terminal.
-e, --exec=file
Run file as executable for child. Default is command.
-f, --foreground
Keep the server process in the foreground and connected to the controlling terminal.
-h, --help
Print help message.
Wait at least n seconds between child restart attempts. Default is 15 seconds.
-i, --ignore=chars
Ignore all characters in chars on access connections. This can be used to shield the child process from input characters that are potentially dangerous, e.g. ^D and ^C characters that would shut down a soft IOC. Use ^ to specify control characters, ^^ to specify a single ^ character.
-k, --killcmd=char
Kill the child process (child will be restarted automatically by default) when char is sent on an access connection. Use ^ to specify a control character, "" for no kill command. Default is ^X.
Kill the child using signal when receiving the kill command. Default is 9 (SIGKILL).
-l, --logport=port
Provide read-only access to the child’s console on port. By default all hosts can connect to port, use the -r (--restrict) option to restrict access to localhost.
-L, --logfile=file
Write a console log of all in- and output to file.
Prefix lines in logs with a time stamp, setting the time stamp format string to fmt. Default is "[<timefmt>] ". (See --timefmt option.)
-n, --name=title
In all server messages, use title instead of the full command line to increase readability.
Do not automatically restart child process on exit.
-p, --pidfile=file
Write the PID of the server process into file to facilitate integration into regular system service administration mechanisms.
Set the format string used to print time stamps to fmt. Default is "%c". (See strftime(3) documentation for details.)
-q, --quiet
Do not write informational output (server). Avoids cluttering the screen when run as part of a system script.
Restrict log connections to localhost.
-V, --version
Print program version.
-w, --wait
Do not start the child immediately. Instead, wait for a telnet connection and a manual start command.
-x, --logoutcmd=char
Log out (close client connection) when char is sent on an access connection. Use ^ to specify a control character. Default is empty.


To start a soft IOC using procServ, change the directory into the IOC’s boot directory. A typical command line would be

procServ -n "My SoftIOC" -i ^D^C 20000 ./st.cmd

To connect to the IOC, log into the soft IOC’s host and connect to port 20000 using

telnet localhost 20000

To connect from a remote machine, ssh to a user account on procservhost and connect to port 20000 using

ssh -t user@procservhost telnet localhost 20000

You will be connected to the soft IOCs console and receive an informative welcome message. All output from the procServ server will start with "@@@" to allow telling it apart from messages that your IOC sends.

> telnet localhost 20000
Connected to localhost.
Escape character is '^]'.
@@@ Welcome to the procServ process server (procServ Version 2.1.0)
@@@ Use ^X to kill the child, auto restart is ON, use ^T to toggle auto restart
@@@ procServ server PID: 21413
@@@ Startup directory: /projects/ctl/lange/epics/ioc/test314/iocBoot/iocexample
@@@ Child "My SoftIOC" started as: ./st.cmd
@@@ Child "My SoftIOC" PID: 21414
@@@ procServ server started at: Fri Apr 25 16:43:00 2008
@@@ Child "My SoftIOC" started at: Fri Apr 25 16:43:00 2008
@@@ 0 user(s) and 0 logger(s) connected (plus you)

Type the kill command character ^X to reboot the soft IOC and get server messages about this action.

Type the telnet escape character ^] to get back to a telnet prompt then "quit" to exit telnet (and ssh when you were connecting remotely).

Though procServ was originally intended to be an environment to run soft IOCs, any process might be started as child. It provides an environment for any program that requires access to its console, while running in the background as a daemon, and keeping a log by writing a file or through a console access and logging facility (such as conserver).

Environment Variables


Sets the file name to write the PID of the server process into. (See -p option.)


If set, procServ starts in debug mode. (See -d option.)

Known Problems

None so far.

Reporting Bugs

Report bugs using the issue tracker at https://github.com/ralphlange/procServ/… or to the author.


Originally written by David H. Thompson <thompsondh@ornl.gov>. Current author: Ralph Lange <ralph.lange@gmx.de>.


GitHub project: https://github.com/ralphlange/procServ


All copyrights reserved. Free use of this software is granted under the terms of the GNU General Public License (GPLv3).


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