Re^2: Passing commands to subroutines

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Re^3: Passing commands to subroutines by ikegami (Patriarch) on Jul 01, 2009 at 18:45 UTC
Your whole reason to use the multiple argument version of `system` was to avoid having the your arguments treated as anything but literal text. And now you're asking why it doesn't work when the code does exactly that. If you want redirection, you'll either have to build a shell command or do it yourself (IPC::Run, IPC::Run3, IPC::Open2, IPC::Open3, etc.)	[reply] [d/l]
Re^3: Passing commands to subroutines by graff (Chancellor) on Jul 02, 2009 at 04:43 UTC
Given that you're facing a problem with tricky file names, the easiest substitute I could imagine for fixing a line of code like this: `system("program $ref_file > $outfile");` [download] would be to do it like this: `open( PROG, "-\|", "program", $ref_file ) or die "can't launch 'program +' on $ref_file: $!\n" open( OUT, ">", $outfile ); while (<PROG>) { print OUT; } close PROG; close OUT;` [download] That ought to take any sort of goofy file name safely in stride (for both input and output files).	[reply] [d/l] [select]
Re^4: Passing commands to subroutines by Anonymous Monk on Jul 02, 2009 at 05:09 UTC
Probably easier to use one of the IPC:: modules, maybe IPC::Cmd	[reply]
Re^3: Passing commands to subroutines by JavaFan (Canon) on Jul 01, 2009 at 17:29 UTC
You'd use `fork` and `exec`. Did you read the `perlipc` manual page I suggested? It contains code that does what you want which you can copy and adjust. I'm not going to cut and paste it for you.	[reply]
Re^3: Passing commands to subroutines by repellent (Priest) on Jul 03, 2009 at 22:57 UTC
Multiple-arg `system()` doesn't quite work like that (read this). Redirection using the shell metacharacter `">"` is handled by the shell, which reads the entire string `"program $ref_file > $outfile"`, parses it, and executes the command with redirection. When you do multiple-arg system, you're going raw and skipping the shell (usually). Redirections have to be performed manually and you'll lose some convenience you get with using a shell. Example: `sub executeComm { my ($outfile, @comm) = @_; print "cmd: <", join("> <" => @comm), ">\n"; # manual redirection - dup(2) STDOUT first open(my $ORIGSTDOUT, ">&" . fileno(STDOUT)) or die $!; open(STDOUT, ">", $outfile) or die $!; # run it! my $exit = system @comm; # restore STDOUT open(*STDOUT, ">&=" . fileno($ORIGSTDOUT)) or die $!; print "exit: ", $exit, "\n"; } print "before\n"; executeComm($outfile, $program, $ref_file); print "after\n";` [download] If you really want a quick-and-dirty fix for your "whitespace-in-filename" problem, place single-quotes around the filenames, as in: `executeComm ("program '$ref_file' > '$outfile'");` [download] Now make sure you don't have single-quotes in the filenames...	[reply] [d/l] [select]
Re^3: Passing commands to subroutines by Anonymous Monk on Jul 01, 2009 at 17:21 UTC
Have you read 'perldoc -f system'? `system "foo >bar";` [download] invokes the shell, and it is the shell which does redirection (> <)	[reply] [d/l]
Re^4: Passing commands to subroutines by citromatik (Curate) on Jul 01, 2009 at 17:44 UTC
<blocquote>Have you read 'perldoc -f system'? Yes... that is why I am asking: you are calling `system` with 1 argument... can you please give me an example like that one (with redirection) using the multiple-arg version? citromatik	[reply] [d/l]


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