Limiting a for loop in perl

user_9077586 0
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I have a bit of perl which is taking in data via a pipe and running

... | perl -0 -wnE 'say for /\d+/g'

which prints every numeric value passed from before the pipe. How would I change this syntax so that only the last ten found are printed?

perl loops regex
2 Answers
... | perl -M5.010 -ne'say for /\d+/g' | tail -10

... | perl -nle'print for /\d+/g' | tail -10

Perl-only:

... | perl -M5.010 -ne'push @n, /\d+/g; splice(@n, 0, -10); END { say for @n }'

... | perl -nle'push @n, /\d+/g; splice(@n, 0, -10); END { print for @n }'

Notes:

  • -E isn't forward compatible, meaning that upgrading Perl could break the program. It should only be used in singe-use code. Replaced with -M5.010 -e.
  • -0 was an attempt to slurp the input file. That's not what it does. -0777 should be used for that. But there's no reason to slurp the input file here.
user_5899240

You can pipe it through the tail unix command to show only the last 10 numbers:

... | perl -0 -wnE 'say for /\d+/g' | tail -10
user_1977580
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