Re: running programs from PERL

Your code lacks error checks on system().
Your code does not give a useful error message should chdir fail. Include $! in die.
There is no need to interpolate $dir in constructing @args. There is also no need to use interpolating quotes on a constant string. my @args=($dir,'&') is sufficient.
The temporary @args array is not needed, use system($dir,'&').
The "&" is passed as a literal argument to program2.pl. If you want THE SHELL to put program2.pl in background, you need to invoke the shell by calling system with a single string argument. That causes a lot of trouble, starting with the need to use proper quoting for an unknown shell that can require different quoting on different systems. So, your chances to invoke "the" shell with proper quoting are quite low, and thus, you open a big security hole.
To create a background process, use fork() and exec() as explained in the perl documentation. On Windows, use system(1,...).

Alexander

--
Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)

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Re^2: running programs from PERL by almut (Canon) on Oct 25, 2009 at 10:22 UTC
The temporary @args array is not needed, use system($dir,'&'). That's right. But it doesn't do much harm either... And in case you want to debug what is actually being passed to `system`, you can simply add a `print @args` without restructering the code, instead of duplicating the argument list and trying to keep both in sync when you make changes. This is especially handy with more unwieldy (OT: or would you say unwieldier?) argument lists. You never know when you'll need it... `my $prog = 'myprog'; my $file = 'myfile'; my @useropts = qw(-bar -baz); my @args = ("/path/to/$prog", '-foo', @useropts, $file, '-o', "$file.o +ut"); print "system(): @args\n"; # debug system (@args); # vs. print join(" ", "system():", "/path/to/$prog", '-foo', @useropts, $fil +e, '-o', "$file.out"), "\n"; # debug system("/path/to/$prog", '-foo', @useropts, $file, '-o', "$file.out");` [download]	[reply] [d/l] [select]

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Re^2: running programs from PERL
by almut (Canon) on Oct 25, 2009 at 10:22 UTC

The temporary @args array is not needed, use system($dir,'&').

That's right. But it doesn't do much harm either... And in case you want to debug what is actually being passed to system, you can simply add a print @args without restructering the code, instead of duplicating the argument list and trying to keep both in sync when you make changes. This is especially handy with more unwieldy (OT: or would you say unwieldier?) argument lists. You never know when you'll need it...

my $prog = 'myprog';
my $file = 'myfile';
my @useropts = qw(-bar -baz);

my @args = ("/path/to/$prog", '-foo', @useropts, $file, '-o', "$file.o
+ut");

print "system(): @args\n";  # debug
system (@args);

# vs.

print join(" ", "system():", "/path/to/$prog", '-foo', @useropts, $fil
+e, '-o', "$file.out"), "\n";  # debug
system("/path/to/$prog", '-foo', @useropts, $file, '-o', "$file.out");
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