qer, runq – queue management for spooled files

qer [ –q subdir ] [ –f file ] root tag reply args
runq [ –adER ] [ –f file ] [ –q subdir ] [ –t time ] [ –r nfiles ] [ –n njobs ] root cmd

Qer creates a control and a data file in a queue directory. The control file contents consist of the tag, reply, and args separated by spaces. The data file contains the standard input to qer. The files are created in the directory root/subdi The names of the control and data files differ only in the first character which is `C' and `D' respectively. Mktemp(2) is used to create the actual names of the control and data file.

Some commands, such as fax (see telco(4)), must queue more files than just the data file. Each file following a –f flag is copied into the queue directory. The names of the copies differ from the name of the data file only in the first character. The first one starts with 'F', the second 'G', etc.

Qer takes the following arguments:
q subdir
Specifies the queue subdirectory to use. If unspecified, the contents of /dev/user are used.
f file
Specifies the files to copy into the queue directory, in the manner described above.

Runq processes the files queued by qer. Runq processes all requests in the directory root/subdir, where subdir is the argument to –q if present, else the contents of /dev/user. Each request is processed by executing the command cmd with the contents of the control file as its arguments, the contents of the data file as its standard input, and standard error appended to the error file E.XXXXXX.

The action taken by runq depends on the return status of cmd. If cmd returns a null status, the processing is assumed successful and the control, data, and error files are removed. If cmd returns an error status containing the word Retry, the files are left to be reprocessed at a later time. For any other status, an error message is mailed to the requester and the files are removed. Runq uses the reply field in the control file as a mail address to which to send an error notification. The notification contains the contents of the control file to identify the failed request.

To avoid reprocessing files too often, the following algorithm is used: a data file younger than one hour will not be processed if its error file exists and was last modified within the preceding 10 minutes. A data file older than one hour will not be processed if its error file exists and was last modified within the preceding hour.

The following flags are accepted by runq:
a    Causes runq to process all user directories in sequence, instead of only the directory of the current user.
E    Causes all files to be reprocessed regardless of the file times.
R    Instructs runq never to give up on a failed queue job, instead leaving it in the queue to be retried.
d    Causes debugging output on standard error describing the progress through the queues.
t    Specifies the number of hours that retries will continue after a send failure. The default is 48 hours.
r    Limits the number of files that are processed in a single pass of a queue. Runq accumulates the entire directory containing a queue before processing any files. When a queue contains many files and the system does not have enough memory, runq exits without making progress. This flag forces runq to
process the directory in chunks, allowing the queue to be drained incrementally. It is most useful in combination with the –q flag.
n    Specifies the number of queued jobs that are processed in parallel from the queue; the default is 1. This is useful for a large queue to be processed with a bounded amount of parallelism.

Runq is often called from cron(8) by an entry such as
0,10,20,30,40,50 * * * * kremvax
/bin/upas/runq –a /mail/queue /mail/lib/remotemail

The entry must be a single line; it is folded here only so it fits on the page.

root/user               queue directory for user
/user/D.XXXXXX       data file
root/user/C.XXXXXX       control file
root/user/E.XXXXXX       error file
root/user/[F–Z].XXXXXX   secondary data files