When printing a job to a CUPS server, you can set up the cupsd.conf parameters PreserveJobHistory and PreserveJobFiles to control how many jobs you want to keep.
CUPS always temporarily stores the actual print job files in directory /var/spool/cups/. The spool files as submitted by the print client (before CUPS' conversion chain of filters kicks in) are always named dNNNNNN-001 (starting with a 'd' as in 'datafile') where NNNNNN is the job ID assigned by CUPS. If you submit a multi-document print job, the second document's spool file within the same job ID is named dNNNNNN-002, and so on...
Also, the same directory will hold files starting with another character, the control files and they will be named cNNNNNN for each job.
I want to dissect these control files files.
When I use the strings tool, it only reveals part of what I want to get at:
Example:
sudo strings /var/spool/cups/d00089
attributes-charset
utf-8H
attributes-natural-language
en-us
printer-uri
%ipp://localhost:631/printers/hp2B
job-originating-user-name
kurtpfeifleB
job-name
hosts!
copies
finishings
job-cancel-after
job-hold-until
no-hold!
job-priority
job-sheets
noneB
none!
number-up
job-uuid
-urn:uuid:ca854775-f721-34a5-57e0-b38b8fb0f4c8B
job-originating-host-name
localhost!
time-at-creation
time-at-processing
time-at-completed
job-id
job-state
job-state-reasons
processing-to-stop-point!
job-media-sheets-completed
job-printer-uri
(ipp://host13.local:631/printers/hp!
job-k-octets
document-format
text/plainA
job-printer-state-message
job-printer-state-reasons
none
Also, that strings output doesn't look very nice.
Question: Is there a programmatic (or other) way to dissect these CUPS job control files and get at their complete content with all included info?
Found an answer myself...
When you compile CUPS from sources, there is the subdirectory cups. It also holds a Makefile specific to this subdir. That Makefile contains a build target named "unittests" which is NOT built by default!
But if you run make unittests it not only runs its unit tests, but also creates a few command line utilities which potentially can be put to quite some good use outside of unit tests too!
For the case to solve my problem, it turns out that the testipp CLI utility is pure gold. See yourself:
sudo ./testipp /var/spool/cups/c00089
operation-attributes-tag:
attributes-charset (charset): utf-8
attributes-natural-language (naturalLanguage): en-us
job-attributes-tag:
printer-uri (uri): ipp://localhost:631/printers/hp
job-originating-user-name (nameWithoutLanguage): kurtpfeifle
job-name (nameWithoutLanguage): hosts
copies (integer): 1
finishings (enum): none
job-cancel-after (integer): 10800
job-hold-until (keyword): no-hold
job-priority (integer): 50
job-sheets (1setOf nameWithoutLanguage): none,none
number-up (integer): 1
job-uuid (uri): urn:uuid:ca854775-f721-34a5-57e0-b38b8fb0f4c8
job-originating-host-name (nameWithoutLanguage): localhost
time-at-creation (integer): 1472022731
time-at-processing (integer): 1472022731
time-at-completed (integer): 1472022732
job-id (integer): 89
job-state (enum): completed
job-state-reasons (keyword): processing-to-stop-point
job-media-sheets-completed (integer): 0
job-printer-uri (uri): ipp://host13.local:631/printers/hp
job-k-octets (integer): 1
document-format (mimeMediaType): text/plain
job-printer-state-message (textWithoutLanguage): Printing page 1, 4% complete.
job-printer-state-reasons (keyword): none
Unfortunately, running make install will not install this tool into the system, and thusly it never gets exposed to any CUPS administrator! Also, Linux distro packagers may easily overlook it. testipp runs under the radar for most CUPS geeks.
There are a few more useful utilities built by make unittests:
These are: testadmin, testarray, testcache, testclient, testconflicts, testcreds, testcups, testdest, testfile, testgetdests, testhttp, testi18n, testlang, testoptions, testppd, testpwg, testraster, testsnmp.
Unfortunately, no Linux distro currently builds and ships these useful tools. So if you know a distro packager, please point him to this discovery here and ask her to package a nice bundle for all end-users of cups-test-utils.rpm, or cups-test-utils.deb or cups-test-utils.tgz or whatever the package name suffixes for his $distro are!
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