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TechTip: Read Printer Output with Qshell |
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Written by MC Press Contributing Author
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Thursday, 21 October 2004 |
Spool files are not for output only!
Everybody knows that spool files
contain output, right? Well, that's not necessarily true. SPOOL is an acronym
meaning Simultaneous Peripheral Operations Online. Spooling was originally
developed for card readers, card punches, and printers as a way to speed up
interaction with those slow devices. So input can be spooled as well as output.
But there's another sense in which spool files can serve as input. It is common
for shops that use packaged software--especially those shops that do not have
the software's source code--to read and process spooled output from one of the
package's programs in order to produce something more to their
liking.
OS/400 programmers are familiar with CL's Copy Spool File
(CPYSPLF) command, which copies spooled output to a database file. As of V5R3,
Qshell includes a utility that is similar in function. Its name is catsplf, and
it will be a welcome addition when my shop goes live with V5R3.
Catsplf
is similar in function to the cat utility, which reads standard input (stdin) or
disk files. Catsplf reads one or more spool files from a job and writes them to
standard output (stdout). You may specify the job in one of two ways. Use the j
option to specify the qualified job name using the OS/400 convention of
jobnumber/user/jobname. Use the p option to specify the job name by its Qshell
process ID. Whichever method you use, follow the job name with the name and
number of the spool file. The spool file name and alpha portions of the job name
are not case-sensitive, so you may use your preference of uppercase or lowercase
letters. You may not use either the special values *ONLY and *LAST that CPYSPLF
supports to specify the spool file number, or the special value * to indicate
the current job.
The following examples illustrate both of these options.
In both cases, the first spool file named QSYSPRT is copied to stdout.
catsplf -j 208922/pamsden/qzshchld qsysprt 1
catsplf -p 854 QSYSPRT 1
There are three other options that can be useful.
The a option
tells Qshell to read all the spool files for a job. In this case, you do not
follow the job identifier with a spool file name and number. Here are two
equivalent expressions that use the a option:
catsplf -a -j 208922/PAMSDEN/QZSHCHLD
catsplf -aj 208922/PAMSDEN/QZSHCHLD
The e and n options number the lines as they are written to stdout. The
difference between the two is that the e option ends each line with a dollar
sign ($). Here are a couple of examples that use the e and n options:
catsplf -anj 208922/PAMSDEN/QZSHCHLD
catsplf -a -e -j 208922/PAMSDEN/QZSHCHLD
For more information about the catsplf utility, see IBM's
iSeries Infocenter. To learn more about Qshell, I recommend Qshell for iSeries by Ted Holt and
Fred A. Kulack.
Paul Amsden has worked with
AS/400 and iSeries systems for more than 10 years.
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Last Updated ( Thursday, 21 October 2004 )
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