Formatting Long String in Backticks

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

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Re: Formatting Long String in Backticks by toolic (Bishop) on Mar 09, 2010 at 23:46 UTC
Your 1st code will execute a single external command, but your 2nd will execute two external commands. I bet you really want something like this: `my $cmd = qq! testing testing ! . qq! ... testing testing !; my $test = qx! $cmd !;` [download]	[reply] [d/l]
Re^2: Formatting Long String in Backticks by Anonymous Monk on Mar 09, 2010 at 23:52 UTC
I am trying to avoid to do what you just did. If this can be written elegantly like this. `my $cmd = qq! testing testing ! . qq! ... testing testing !;` [download] then why can't this code be re-written elegantly as well? `my $test = qx! testing testing ! . qx! ... testing !;` [download] There must be a way to write the qx where I do not need to use $cmd anymore.	[reply] [d/l] [select]
Re^3: Formatting Long String in Backticks by rovf (Priest) on Mar 10, 2010 at 08:58 UTC
then why can't this code be re-written elegantly as well? Because the dot (.) is defined as catenating strings. Hence, `qx(a).qx(b)` [download] is valid, but is defined as catenating the result of qx(a) and the result of qx(b), which is of course different from `qx(a b)`. -- Ronald Fischer <ynnor@mm.st>	[reply] [d/l] [select]
Re^3: Formatting Long String in Backticks by AnomalousMonk (Archbishop) on Mar 10, 2010 at 00:11 UTC
Stupid Array Interpolation Trick #158: `>perl -wMstrict -le "my $test = qx{ @{[ qw(echo testing ...)[0, 1, 1, 1, 2, 1] ]} }; print qq{'$test'}; " 'testing testing testing ... testing '` [download]	[reply] [d/l]
Re: Formatting Long String in Backticks by ahmad (Hermit) on Mar 09, 2010 at 23:46 UTC
Something like this ? my $test = q! testing testing ! . q! ... testing testing !; my $cmd = `$test`; [download]	[reply] [d/l]
Re^2: Formatting Long String in Backticks by toolic (Bishop) on Mar 09, 2010 at 23:53 UTC
Keep in mind that q!! will not interpolate, but qx!! will. This is importatnt if `testing` actually contains variables.	[reply] [d/l]
Re: Formatting Long String in Backticks by johngg (Canon) on Mar 10, 2010 at 23:07 UTC
If you don't need interpolation, put your long command string into an array instead using the quote-words (`qw{ ... }` in Quote Like Operators) operator which allows you to break the word list over multiple lines. `knoppix@Microknoppix:~$ perl -E ' > @cmd = qw{ > ps > -ef > \| > grep > gnome > \| > grep > -v > grep > }; > $res = qx{ @cmd }; > print $res;' knoppix 3829 1 0 09:40 ? 00:00:01 gnome-terminal knoppix 3834 3829 0 09:41 ? 00:00:00 gnome-pty-helper knoppix 3856 1 0 09:41 ? 00:00:30 gnome-terminal knoppix 3858 3856 0 09:41 ? 00:00:00 gnome-pty-helper knoppix 4006 4005 0 09:43 ? 00:00:00 gnome-pty-helper knoppix@Microknoppix:~$` [download] Even if you do need interpolation you can use this method by using push and breaking your word list up a bit so that interpolated variables go in the gaps. `knoppix@Microknoppix:~$ perl -E ' > $lookFor = q{gnome}; > push @cmd, > qw{ > ps > -ef > \| > grep > }, > $lookFor, > qw{ > \| > grep > -v > grep > }; > $res = qx{ @cmd }; > print $res;' knoppix 3829 1 0 09:40 ? 00:00:02 gnome-terminal knoppix 3834 3829 0 09:41 ? 00:00:00 gnome-pty-helper knoppix 3856 1 0 09:41 ? 00:00:30 gnome-terminal knoppix 3858 3856 0 09:41 ? 00:00:00 gnome-pty-helper knoppix 4006 4005 0 09:43 ? 00:00:00 gnome-pty-helper knoppix@Microknoppix:~$` [download] I hope this is of use. Cheers, JohnGG	[reply] [d/l] [select]