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Using awk to print duplicate lines of a file only once | ||
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The following awk script prints only duplicated lines in a file, and these lines only once. The line 'deux' comes three times, but will only be output once.
awk 'seen[$0]++ == 1' <filename>
Sample input file:
eins deux drei quattro deux sechs drei acht huit neuf six deux
The output:
deux drei |