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sed, a stream editor

4.16 Remove All Duplicated Lines

This script prints only unique lines, like `uniq -u'.

#!/usr/bin/sed -f # Search for a duplicate line --- until that, print what you find. $b N /^\(.*\)\n\1$/ ! { P D } :c # Got two equal lines in pattern space. At the # end of the file we simply exit $d # Else, we keep reading lines with N until we # find a different one s/.*\n// N /^\(.*\)\n\1$/ { bc } # Remove the last instance of the duplicate line # and go back to the top D