Question

How can I use bash syntax in Perl’s system() command?

I have a command that is bash-specific, e.g. the following, which uses bash’s process substitution:

 diff <(ls -l) <(ls -al) 

I would like to call it from Perl, using

 system('diff <(ls -l) <(ls -al)') 

but it gives me an error because it’s using sh instead of bash to execute the command:

sh: -c: line 0: syntax error near unexpected token `(' sh: -c: line 0: `sort <(ls)' 

Answer 1

Tell Perl to invoke bash directly. Use the list variant of system() to reduce the complexity of your quoting:

my @args = ( 'bash', '-c', 'diff <(ls -l) <(ls -al)' ); system(@args); 

You may even define a subroutine if you plan on doing this often enough:

sub system_bash {   my @args = ( 'bash', '-c', shift );   system(@args); }  system_bash('echo $SHELL'); system_bash('diff <(ls -l) <(ls -al)');