Question using system.

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I have an simple question. My perl program invokes another program called getfilesdata using system() and needs to catch output from getfilesdata to use in the perl program. getfilesdata takes as input the filename and prints some information to screen. Issue: I need to get the output from the getfilesdata into my perl program.

system(getfilesdata file.txt); //calls getfilesdata

Example of output from getfilesdata: An 32 bit string and file name is
+ displayed on the screen. 
kdw3343kajkdaa11dkf file.txt
[download]

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Re: Question using system. by toolic (Bishop) on Jul 10, 2008 at 14:53 UTC
From the free manual for system: This is not what you want to use to capture the output from a command, for that you should use merely backticks or qx//, as described in "`STRING`" in perlop. my @output = `getfilesdata file.txt`; [download] Update: This is also a FAQ in perlfaq8, Why can't I get the output of a command with system()?	[reply] [d/l]
Re^2: Question using system. by pjotrik (Friar) on Jul 10, 2008 at 15:05 UTC
Or you may use open with pipe, as described in perlipc. That allows you to work with the commands output as with any other (readonly) filehandle. `open(my $cmd, 'getfilesdata file.txt \|')`	[reply] [d/l]
Re^3: Question using system. by ikegami (Patriarch) on Jul 10, 2008 at 18:28 UTC
Better yet: `open(my $cmd, '-\|', 'getfilesdata', 'file.txt')` [download]	[reply] [d/l]
Re^4: Question using system. by oko1 (Deacon) on Jul 10, 2008 at 20:36 UTC
Re^5: Question using system. by ikegami (Patriarch) on Jul 10, 2008 at 20:54 UTC
Some notes below your chosen depth have not been shown here
Re^2: Question using system. by rovf (Priest) on Jul 11, 2008 at 09:17 UTC
Why can't I get the output of a command with system()? Because it is not designed that way. `system` has a different purpose, that is running a program, which even might be interactive. Think about, for instance, `system('bash')`. -- Ronald Fischer <ynnor@mm.st>	[reply] [d/l] [select]
Re: Question using system. by harishnuti (Beadle) on Jul 10, 2008 at 14:51 UTC
one simple solution can be as below... my $output = undef; $output = qx(getfilesdata file.txt); # which is same as using back ticks $output = `getfilesdata file.txt`; [download] you will get output in variable, but remember you cannot check return code	[reply] [d/l]
Re^2: Question using system. by toolic (Bishop) on Jul 10, 2008 at 16:08 UTC
but remember you cannot check return code From perlvar, `$?`: The status returned by the last pipe close, backtick (`` ) command, successful call to wait() or waitpid(), or from the system() operator. use strict; use warnings; my $out; $out = `ls /tmp`; print "tmp status: $?\n"; $out = `ls /foo`; print "foo status: $?\n"; __END__ tmp status: 0 ls: /foo: No such file or directory foo status: 256 [download]	[reply] [d/l] [select]