executing perl script using -e

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

Replies are listed 'Best First'.
Re: executing perl script using -e by shmem (Chancellor) on Sep 22, 2014 at 12:53 UTC
Any clues why and how can I do that? Yes. You are giving perl a string and nothing more. Perl looks at the string and happily throws it away. `# string "system(/usr/bin/perl /root/test.pl)" # program system "/usr/bin/perl /root/test.pl";` [download] So, omit the double quotes; try instead `perl -e 'system "/usr/bin/perl /root/test.pl"'` [download] or this `perl -e 'system "/usr/bin/perl","/root/test.pl"'` [download] See system for the difference between the two expressions. perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'	[reply] [d/l] [select]
Re: executing perl script using -e by hippo (Archbishop) on Sep 22, 2014 at 12:55 UTC
Your perl one-liner does not do anything because your quotation marks are in the wrong place. Simply using the `-w` option would have alerted you to this: `$ perl -we '"system(/usr/bin/perl /root/test.pl)"' Useless use of a constant (system(/usr/bin/perl /root/test.pl)) in voi +d context at -e line 1.` [download] If you correct the one-liner you would have more luck. Although, why you call a perl script to invoke a shell to call another perl script is not clear. Perhaps if you can explain what it is you are actually trying to accomplish someone could suggest an alternative approach.	[reply] [d/l] [select]
Re: executing perl script using -e by LanX (Saint) on Sep 22, 2014 at 12:55 UTC
Why on earth do you want 3 levels of indirection to execute your Perl script? Cheers Rolf _{(addicted to the Perl Programming Language and ☆☆☆☆ :)}	[reply]
Re: executing perl script using -e by karlgoethebier (Abbot) on Sep 22, 2014 at 12:56 UTC
`perl -e 'system("/usr/bin/perl /root/test.pl");' host:~ # ls -l /tmp/1 -rw-r--r-- 1 root root 0 Sep 22 14:54 /tmp/1` [download] BTW: Why do you need to call perl ~~three~~ two times to execute a shell command? Regards, Karl «The Crux of the Biscuit is the Apostrophe»	[reply] [d/l]
Re: executing perl script using -e by choroba (Cardinal) on Sep 22, 2014 at 12:56 UTC
You misplaced the quotes. system expects a string (or a list of strings), so you need to enclose its arguments in quotes. You don't need to quote the whole script twice for the shell, though - once is enough. `perl -e 'system("/usr/bin/perl /root/test.pl")'` [download] لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l]
Re: executing perl script using -e by Anonymous Monk on Sep 22, 2014 at 13:10 UTC
See the Basic debugging checklist, the first item is to `use warnings; use strict;`. How to apply them to one-liners: hippo already mentioned `-w`, adding strict and diagnostics you get `-wMstrict -Mdiagnostics`: $ perl -wMstrict -Mdiagnostics -e '"system(/usr/bin/perl /root/test.pl)"' Useless use of a constant ("system(/usr/bin/perl /root/test."...) in void context at -e line 1 (#1) (W void) You did something without a side effect in a context that does nothing with the return value, such as a statement that doesn't return a value from a block, or the left side of a scalar comma operator. Very often this points not to stupidity on your part, but a failure of Perl to parse your program the way you thought it would. ... [download]	[reply] [d/l] [select]
Re: executing perl script using -e by GotToBTru (Prior) on Sep 22, 2014 at 19:53 UTC
`touch /tmp/1` [download] You invoke perl to run a shell to run perl to run a shell command. Let's just omit the middle ~~man~~ committee. 1 Peter 4:10	[reply] [d/l]