A very good tip. I thought I was defending against, for example, passing in a hashref by mistake. But it appears that perl will throw an error in this case. Yay perl!

However, I had to modify the sub you proposed to get it to work:

 return join '', map { "( ( $_ ) & );" } @{ $_[0] };

Here's the code with a hashref, which gets thrown a nice error. 

#!/usr/bin/perl
use strict;
use warnings;
use Carp qw(confess);

my @commands = map {
  "echo $_; sleep 2";
} qw(a b c d e);

#does first, waits two seconds, does the second, waits two seconds, et
+c. (should take about ten seconds)
#for my $bash_command ( @commands  ) {
#  time_bash_command($bash_command);
#}

#does commands in parallel. (should take about two seconds)
my $parallel_running_command = parallelize_bash_commands([@commands]);
$parallel_running_command = parallelize_bash_commands( { a => 'sleep 2
+', b=> 'sleep 2', c => 'sleep 2'  } );


sub parallelize_bash_commands {

   return join '', map { "( ( $_ ) & );" } @{ $_[0] };
   #return join '', map { "( ( $_ ) & );" } @{ my $input = shift or di
+e "no input" }; # alternative -- also works, and checks if you forgot
+ to pass in a var.
   time_bash_command($parallel_running_command);
}

sub time_bash_command {
  my $command = shift or die "no command";
  $command = "time `$command`";
  print "$command\n";
  print `$command`;
}

[download]

In reply to Re^2: Using perl to speed up a series of bash commands by transforming them into a single command that will run everything in parallel. by tphyahoo
in thread Using perl to speed up a series of bash commands by transforming them into a single command that will run everything in parallel. by tphyahoo

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.