CTSS: RUNCOM and FIB: scripting and background jobs
Another first for CTSS was the idea of collecting a sequence of
interactive commands into a script file that could be run as a single
unit, which helped simplify complex or repetitive tasks. The command
that does this is called RUNCOM, for Run Commands. This influenced
the Multics shell and the terminology carried over to Unix in file
names containing the letters rc, eg /etc/init.rc.
Associated with this is FIB, the Foreground Initiated "Background"
batch job scheduler, which allows you to execute RUNCOM jobs without
being logged in. Let's take a look at both. Note that FIB is different
from the ability to run FMS batch jobs, which existed before CTSS.
FIB running a job submitted by GUEST.
Using RUNCOM
At its simplest, this is just a text file with name2 of RUNCOM
containing a list of commands to run in order. For example, if I am
editing, printing, compiling and running a program FOO I could write
the following to a file DEV RUNCOM
EDL FOO MAD P FOO MAD MAD FOO LOADGO FOO
and then type RUNCOM DEV to execute it.
By using parameters we can generalise this to work with other source
code files. Parameters are introduced with the CHAIN statement.
CHAIN PROG EDL PROG MAD P PROF MAD MAD PROG LOADGO PROG
and then executed by typing, for example RUNCOM DEV FOO.
We can generalise further to allow MAD and FAP code to be developed by noticing that the name2 and translator can be parameterised as one item:
CHAIN PROG TRANS EDL PROG TRANS P PROF TRANS TRANS PROG LOADGO PROG
and run as RUNCOM FOO MAD
Optional parameters can be introduced using (NIL). Say sometimes I
want to give options to the translator command, like (LIST). I can
change the runcom file to be:
CHAIN PROG TRANS OPT EDL PROG TRANS P PROF TRANS TRANS PROG OPT LOADGO PROG
and then invoke as RUNCOM FOO MAD (NIL) if I don't want any options,
or RUNCOM FOO MAD (LIST) if I want the compile command to be MAD
FOO (LIST).
(END) is a similar parameter which will end the line at that point
if detected.
Finally, a line starting with * in the runcom file will act as a
comment; a line starting with $ will be echoed to the console.
Using FIB
FIB allows you to submit a runcom file for later execution. It is
invoked as:
FIB NAME1 -LIMIT- -TIME- -DAY-
where NAME1 is the name1 of a runcom file, eg FOO for FOO
RUNCOM.
The next three parameters are optional. LIMIT sets a maximum CPU
time in minutes that the job can run for, with a default of 5. The
last two set a time and date before which the job cannot start.
Once you submit a job, you can cancel it with DELFIB or query it
with PRFIB. Only one job can be submitted at a time.
fib make
W 914.1
R .016+.016
prfib
W 914.3
JOBNAM LIMIT DATE TIME
MAKE 5 03/09 0914.1
R .016+.016
In addition to any time/date argument, the job will not run until you have logged out. Behind the scenes, the FIB job switches to your ID and executes the job, as can be seen from the screenshot of the console at the top of this post.
This is because CTSS only allows one task per ID to be running at a time. Had you tried to log in while the job was running, you would see a warning and if you continued the FIB job would be cancelled.
After the job has finished, you will see its console output in a file
called $$$FIB OUTPUT. This will be in 12-bit mode, so use P to
view the file.
Further details
See the CTSS Programmer's Guide p326 for RUNCOM and p287 for FIB.
Questions, corrections, comments
May 2025: Tom Van Vleck provided a correction for the name of FIB,
noted the difference between this and FMS batch jobs and the output
format for FIB jobs.
I welcome any questions or comments, and also especially any corrections if I have got something wrong. Please email me at rupert@timereshared.com and I will add it here and update the main text.
A sample session using EDL, changing two lines in a file.
Using the IBM 029 Card Punch. Source: 
The CTSS Programmer's Guide with its "candy stripe" cover.