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The following is a compilation of '''useful one-line scripts for [[Perl]]'''. The original was compiled by Tom Christiansen, however, I have converted it into the wiki format and have added more examples (always adding more).

==Perl one-liners==
*run contents of "my_file" as a program
 perl my_file

*run debugger "stand-alone"
 perl -d -e 42

*run program, but with warnings
 perl -w my_file

*run program under debugger
 perl -d my_file

*just check syntax, with warnings
 perl -wc my_file

*useful at end of "find foo -print"
 perl -nle unlink

*simplest one-liner program
 perl -e 'print "hello world!\n"'

*add first and penultimate columns
 perl -lane 'print $F[0] + $F[-2]'

*just lines 15 to 17
 perl -ne 'print if 15 .. 17' *.pod

*in-place edit of *.c files changing all foo to bar
 perl -p -i.bak -e 's/\bfoo\b/bar/g' *.c

*command-line that prints the first 50 lines (cheaply) 
 perl -pe 'exit if $. > 50' f1 f2 f3 ...

*delete first 10 lines
 perl -i.old -ne 'print unless 1 .. 10' foo.txt

*change all the isolated oldvar occurrences to newvar
 perl -i.old -pe 's{\boldvar\b}{newvar}g' *.[chy]

*command-line that reverses the whole file by lines
 perl -e 'print reverse <>' file1 file2 file3 ....

*find palindromes
 perl -lne 'print if $_ eq reverse' /usr/dict/words

*command-line that reverse all the bytes in a file
 perl -0777e 'print scalar reverse <>' f1 f2 f3 ...

*command-line that reverses the whole file by paragraphs
 perl -00 -e 'print reverse <>' file1 file2 file3 ....

*increment all numbers found in these files
 perl i.tiny -pe 's/(\d+)/ 1 + $1 /ge' file1 file2 ....

*command-line that shows each line with its characters backwards
 perl -nle 'print scalar reverse $_' file1 file2 file3 ....

*delete all but lines between START and END
 perl -i.old -ne 'print unless /^START$/ .. /^END$/' foo.txt

*binary edit (careful!)
 perl -i.bak -pe 's/Mozilla/Slopoke/g' /usr/local/bin/netscape

*look for dup words
 perl -0777 -ne 'print "$.: doubled $_\n" while /\b(\w+)\b\s+\b\1\b/gi'

*command-line that prints the last 50 lines (expensively)
 perl -e '@lines = <>; print @lines[ $#lines .. $#lines-50' f1 f2 f3 ...

==External links==
*[http://www.ibm.com/developerworks/linux/library/l-p101/ Cultured Perl: One-liners 101]
*[http://www.ibm.com/developerworks/linux/library/l-p102.html Cultured Perl: One-liners 102]
*[http://homepages.cwi.nl/~rooij/programming/oneliners.html Oneliners and other very short programs]
*[http://www.perlmonks.org/?node_id=135345 Perl's pearls]
*[http://www.ajs.com/ajswiki/Perl_one-liners Perl one-liners]
*[http://www.visualgenomics.ca/gordonp/oneliners.html Perl one-liners for the bioinformatician]
*[http://sial.org/howto/perl/one-liner/ Perl One Liners]
*[http://www.amazon.com/o/ASIN/1932394508/sialorg-20/ref=nosim Minimal Perl: For UNIX and Linux People]

[[Category:Scripting languages]]