one liners

remove blank lines:

perl -ni.bak -e 's/^\s*$//' somefile

remove comment lines:

perl -ni.bak -e 's/^#.*$//' somefile

install some::module

perl -MCPAN -e 'install Some::Module'

Search and Replace:

perl -pi -e 's/change/to this/g' somefile

Find Repeated Lines:

perl -ne 'print if $x{$_}++' somefile

Generate an 8 Letter (Weak) Password:

perl -le 'print map { (a..z)[rand 26] } 1..8'

Find Palindromes:

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

Strip Most HTML:

cat index.htm | perl -ne 's/\<[^<]*\>//g ;print $_'

Convert File to Lowercase:

perl -ne 'tr/A-Z/a-z/; print' somefile

Add Line to Beginning of File:

perl -0777 -i -ne 'print "first line here\n$_"; somefile

Find href tags:

perl -nle 'print $1 while /\<a\b[^\>"]*?\bhref=\"?([^\>"]*)/g' somefile

Remove Duplicate Lines

perl -e '$u=0;while(<>){if(!($s{$_}++)){print $_;$u++}} warn "$u unique of $. total lines.\n"' infile outfile

Available DBI Drivers

perl -e "use DBI; print map qq~$_\n~, DBI->available_drivers;";

Replace Text

perl -i -pe 's/OLD/NEW/g' /path/to/file
digitalcrunch@penguin:~/techgrimoire2/checkpoint-maestro$ find . -name "*.markdown" -exec perl -i -pe 's|permalink: /maestro/|permalink: /checkpoint-maestro/|g' {} +
digitalcrunch@penguin:~/techgrimoire2/checkpoint-maestro$ find . -name "*.markdown" -exec perl -i -pe 's|parent: Maestro|parent: Check Point Maestro|g' {} +