Re: one liner string extraction

Hi, $1 is reset on each attempted match, so if a failed match occurs after your last match, $1 will be unset.

perl -ne '$string=$_ if /Successfully sent/;  $match = $1 if $string =
+~ /^(.*) INFO.*$/; END{print $match}' $logfile
[download]

Hope this helps!

The way forward always starts with a minimal test.

Comment on Re: one liner string extraction Select or Download Code

Replies are listed 'Best First'.
Re^2: one liner string extraction by vr (Curate) on Nov 02, 2017 at 15:33 UTC
Hm-m, while the above solution works, but by way of nitpicking and because of TIMTOWTDI: $1 is reset on each attempted match `$1` is reset on each successful match, and restored on each scope end. Scope end happens twice (rather, n + 1) in OP: 1st on every loop iteration (-n), second at program finishing but before executing END block(s). `>perl -wE "'a'=~/(a)/; 'a'=~/b/; say $1" a >perl -wE "'a'=~/(a)/; 'a'=~/a/; say $1" Use of uninitialized value $1 in say at -e line 1. >perl -wE "'a'=~/(a)/; END { say $1 }" Use of uninitialized value $1 in say at -e line 1.` [download] But we can abuse the fact that, unlike other global variables related to regular expressions, the $^R is not dynamically scoped. Further, let's match only once, and also have a little fun and save us a few keystrokes by using a secret (END will also do, of course): `>perl -ne "/^(.*) INFO.+Successfully sent(?{$1})/ }{ print $^R" file` [download]	[reply] [d/l] [select]
Re^2: one liner string extraction by natxo (Scribe) on Nov 02, 2017 at 12:00 UTC
of course! Thanks, works like a charm.	[reply]