Beginners	Built-In Functions	Advanced	CGI Applications
Introduction Syntax Operators Variables Scope Data Types Flow Control Subroutines RegEx	Arithmetic Strings Arrays Hashes Date/Time Printing	Files Directories Databases Reports RegEx Exceptions System Calls Modules One Liners Reference	Unix Forms CGI Cookies

One Liners
Perl allows a complete, single line script to be run from the command line. These 'one liners'
can be a quick way of making changes, finding information or presenting file content.

Most Perl programmers don't use one liners and are happy to use more relaxed, readable
code in standard multi-line script files. Other programmers enjoy the speed and convenience
of one liners or simply enjoy the challenge of cramming as much code/logic into one line as
possible.

The following three sections provide information on how to create one liners, over 75 scripts,
and detailed explanation of how the scripts work.

One Liner Basics Just the Scripts More Detailed Script Explanation

One Liner Categories
What can you do with one liners? The following list is a categorical listing of the one liners provided
in this tutorial. The corresponding scripts are provided below.

Test Before Using Syntax CGI Module Version Contents of @INC Find and Replace Pattern Pattern (redirect) Pattern (edit in place) Left/Right spaces Left spaces Right spaces Collapse spaces Remove first column Replace blank lines Remove blank lines Collapse blank lines Insert Double space Line at top Line at bottom Line at arbitrary position Line numbers Columns Conversion DOS to Unix Unix to DOS

Print First matching line Matching lines Matching content Matching lines/filename Non-matching lines Non-blank lines Non-comments lines Lines before marker Lines through marker Lines between markers Lines outside markers Line 1 Line r Lines r..s Lines outside r..s Lines between r..s First n lines Last n lines Last line Long lines Specific column Matching paragraphs All words Unique words Duplicate words Format Lower case text Lower case text (UC 1st) Upper case 1st char Lower case filenames Upper case filenames Wordwrap

Reverse Characters in Line Characters in File Lines Columns Paragraphs HTML Add Title info Add Footnote Extract URLs Statistics Character count Vowel count Character distribution Word distribution Line count Word count Unique word count Duplicate word count Math Add command line numbers Add columns (r plus s) Add columns (r thru s) Add lines (column 1) Add lines (column n) Increment all numbers Create random numbers Rot13 Encryption Test number for prime

Single Line Summary of One Liners
And here are the one liner scripts. Several of the categories list multiple ways to perform
the task. Alternatives are presented in random order.

Test Before Using Syntax: perl -wc script.pl CGI module version: perl -MCGI -e "print $CGI::VERSION" Contents of @INC: perl -e "foreach $a (@INC) { print qq/$a\n/}" Find and Replace Pattern: perl -pe "s/aaa/bbb/g" input.txt perl -pe "s/\baaa\b/bbb/g" input.txt Pattern (redirect): perl -pe "s/aaa/bbb/g" input.txt > output.txt perl -pe "s/\naaa/\bbbb/g" input.txt > output.txt Pattern (edit in place): perl -i.bak -pe "s/aaa/bbb/g" input.txt perl -i.bak -pe "s/\baaa/\bbbb/g" input.txt Left/Right spaces: perl -lpe "s/^\s+//;s/\s+$//" input.txt Left spaces: perl -lpe "s/^\s+//" input.txt Right spaces: perl -lpe "s/\s+$//" input.txt Collapse spaces: perl -pe "s/( )+\1/$1/g" input.txt Remove first column: perl -nale 'shift@F;print"@F"' Replace blank lines: perl -ne "/\S/? print : print qq/subtext\n/" input.txt perl -ne "/\S/ && print" input.txt Remove blank lines: perl -pe "unless (/\S/) {$_=''}" input.txt perl -ane "@F && print" input.txt perl -lp00ee input.txt Collapse blank lines: perl -0777 -pe "s/\n+/\n\n/g;chop" input.txt perl -00 -pi.bak -e 1 input.txt Insert Double space: perl -pe "$_.=$/" input.txt perl -pe "$_.=qq/\n/" input.txt perl -0777 -lpe "s/\n/\n\n/g" input.txt Line at top: perl -e "@a=<>;print qq/new line\n/;print @a" input.txt > output.txt perl -0777 -pe "print qq/newline\n/" input.txt perl -pe "print qq/newline\n/ if $.==1" input.txt perl -e "@a = <>; unshift (@a,qq/newline\n/);print @a" input.txt Line at bottom: perl -e "@a=<>;print @a; print qq/new line\n/" input.txt > output.txt perl -0777 -pe " END {print qq/\nnewline/}" input.txt perl -e "open (IN,'>>input.txt');print IN qq/\nnewline/" Line at arbitrary pos: perl -pi.bak -le "print 'New line added!!' if $. == 3" input.txt perl -pi.bak -le "print 'New line added!!' if $. == 3; close ARGV if eof" input1.txt input2.txt Line numbers: perl -pe "$_ = sprintf '%04d %s', $., $_" input.txt perl -pe "$_ = qq/$.\t$_/" input.txt perl -pe "$_ = qq/$. - $_/" input.txt Columns: -- Conversion DOS to Unix: perl -i.bak -pe "s/\n/\r/g" input.txt Unix to DOS: perl -i.bak -pe "s/\r/\n/g" input.txt Print First Matching line: perl -ne "print and last if /pattern/" input.txt Matching lines: perl -nle "print if /pattern/" input.txt Matching content: perl -nle "print $1 if /(pattern)/" input.txt Matching lines/filename: perl -nle "print qq/$ARGV: $_/ if /pattern/" input1.txt input2.txt Non-matching lines: perl -nle "print unless /(pattern)/" input.txt Non-blank lines: perl -ne "print if /\S/" input.txt perl -ne "print unless /^$/" input.txt Non-comment lines: perl -ne "print unless /^#/" input.txt Lines before marker: perl -pe "last if /^START$/" input.tx Lines through marker: perl -ne "print; last if /pattern/" input.txt Lines between markers: perl -ne "print if /^START$/ .. /^END$/" input.txt Lines outside markers: perl -ne "print if ! /^START$/ .. /^END$/" Line 1 perl -e "$_=<>;chomp;print" input.txt Line r perl -nle "print if $. == 5" input.txt perl -ne 'print and exit if $. == 5' file perl -ne 'print and last if $. == 5' file Lines r .. s: perl -ne "print if 5 .. 8" input.txt perl -ne "print if $. >= 5; exit if $. >= 8" input.txt Lines outside r..s: perl -ne "print unless 5 .. 8" input.txt perl -ne "print if $. < 5 || $. > 8;" input.txt Lines between r..s: perl -ne "print if 5+1 .. 8-1" input.txt perl -ne "print if $. > 5 && $. < 8; exit if $. >= 8" input.txt First n lines: perl -pe "exit if $. > 5" input.txt perl -ne "print if 1 .. 5" input.txt Last n lines: perl -e "@a = <>; print @a[$#a-5+1 .. $#a]" input.txt Last line: perl -e "@a = <>; print $a[$#a]" input.txt perl -e "print+()[-1]" input.txt Long lines: perl -ne "print if length > 80" input.txt Specific column: perl -pale "$_=$F[1]" input.txt perl -ple "@a=split;$_=$a[1]" input.txt Matching paragraphs: perl -00 -ne "print if /pattern/" input.txt All words: perl -0777 -lne "foreach (sort split){print qq/$_\n/}" input.txt Unique words: perl -0777 -ne "foreach (sort split){print qq/$_\n/ if $_ ne $old; $old=$_}" input.txt perl -0777 -ane "@U{@F}=();print join(qq/\n/,sort keys %U)" input.txt Duplicate words: perl -0777 -ne "foreach (sort split){print qq/$_\n/ if $_ ne $old; $old=$_}" input.txt Double quoted strings: perl -lne "print $1 while (/\"(.*?)\"/g)" input.txt Format Lower case text: perl -pe "$_=lc $_" input.txt perl -ne "print lc" input.txt perl -pe "tr/A-Z/a-z/" input.txt Lower case text (UC 1st): perl -ne "print ucfirst lc" input.txt perl -pe "s/(\w)(.*)$/\U$1\L$2/" input.txt perl -pe "s/\w.+/\u\L$&/" input.txt Upper case 1st char: perl -ne "print ucfirst $_" input.txt perl -pe "s/(\w)(.*)$/\u$1$2/" input.txt perl -pe "s/\w.+/\u$&/" input.txt Lower case filenames: perl -e "@f=<*.jpg>;foreach (@f) {rename $_, lc($_) }" perl -e "for (glob qq/*jpg/) { rename $_, lc($_) }" Upper case filename: perl -e "@f=<*.jpg>;foreach (@f) {rename $_, uc($_) }" perl -e "for (glob qq/*jpg/) { rename $_, uc($_) }" Wordwrap: perl -000 -pe "tr/ \t\n\r/ /;s/(.{50,72})\s/$1\n/g;$_.=qq/\n/x2" input.txt Reverse Characters in each line: perl -nle "print scalar reverse $_" input.txt Characters in file: Lines in each file: perl -e "@L=reverse<>; chomp @L; print join(qq/\n/,@L)" input.txt Columns in each file: perl -lane "@new = reverse @F; print join(' ',@new)" input.txt Paragraphs in each file: perl -00 -e "print reverse <>" input.txt HTML Get URL perl -e "use LWP::Simple; getprint 'http://www.garybeene.com'" perl -MLWP::Simple -e "getprint 'http://www.garybeene.com'" Add Title info: perl -pe "s/<title>/<title>garybeene.com/i" input.txt Add Footnote: perl -pe "s/<\/body>/<address>Gary Beene<\/address><\/body>/i" input.txt Extract URLs: perl -nle "print $1 while /\<a\b[^\>\"]*?\bhref\s*=\s*[\"]?([^\>\"]*)/gi" input.txt Statistics Character count: perl -lne "$c += length; END { print $c }" input.txt perl -0777 -ne "s/\n//g; print length($_)" input.txt Vowel count: perl -ne "END{print $c} $c += tr/aeiou//" input.txt Character distribution: perl -0777 -ne "s/\n//g;@C=split//;for(@C){$C{$_}++} END{for(sort keys %C){print qq/$_,: $C{$_}\n/}}" input.txt Word distribution: perl -ane "for(@F){$F{$_}++} END{for(sort keys %F){print qq/$_: $F{$_}\n/}}" input.txt Line count: perl -ne "END { print $. }" input.txt perl -e "@L=<>; print scalar @L" input.txt perl -ne "END {print $.}" input.txt Word count: perl -ane "$c += scalar @F; END {print $c}" input.txt perl -ane "$c += $#F; END {print $c}" input.txt perl -0777 -ane "print scalar @F" input.txt perl -0777 -ne "print scalar split" input.txt Unique word count: perl -0777 -ne "foreach (sort split){if ($_ ne $old) {print qq/$_\n/;$old=$_;$c++}} END{print $c}" input.txt Duplicate word count: perl -0777 -ne "foreach (sort split){if ($_ eq $old) {print qq/$_\n/;$old=$_;$c++}} END{print $c}" input.txt Math Add command line numbers: perl -e "print eval join('+', @ARGV)" 5 10 15 20 perl -e "foreach (@ARGV) {$c+=$_};print $c" 5 10 15 20 Add columns (r plus s): perl -ane "print $F[0]+$F[2];print qq/\n/" input.txt Add columns (r thru s): perl -ane "foreach (@F[0..2]){$c+=$_};print qq/$c\n/;$c=0" input.txt Add lines (column 1): perl -ne "$c+=$_; END{print $c}" input.txt Add lines (column n): perl -ane "$c+= $F[0]; END { print $c }" input.txt perl -lane "print $s += $F[2]" input.txt Increment all numbers: perl -pe "s/(\d+)/ 1 + $1 /ge" input.txt Create random numbers: perl -e "foreach (1..10) { print int(rand(101)).qq/\n/ }" Rot13 Encryption: perl -pe "tr/A-Za-z/N-ZA-Mn-za-m/; print" input.txt Test number for prime: perl -le "print 'PRIME' if (1 x shift) !~ /^(11+)\1+$/ " 37

Author Credits
I've written several of these scripts myself, but many have simply been gathered from
various web sites, then tested and modified slightly to fit my own tastes in coding
syntax. I didn't keep track of where I got the scripts but I'm working now to locate
the original sources so that I can place credit here for the authors. If you think
you're due credit for any of these entries please let me know. Here are sources
that I've verified.

• Jeremy Mates

If you have any suggestions or corrections, please let me know.