uniqnosort : uniq replacement -- shell script to get unique lines WITHOUT prior sort -- preserves original ordering where any subsequent duplicates are removed. Duplicates do NOT have to be adjacent to each other!

uniqnosort

#!/usr/bin/env bash
#              bash 4.1.5(1)     Linux Ubuntu 10.04           Date : 2011-01-16
#
# _______________|  uniqnosort : get unique lines WITHOUT sorting.
#
#           Usage:  uniqnosort  [file, or use as pipe]
#
#              NB:  More famous "uniq" requires duplicates on adjacent lines. 
#                   If you really want to sort and get uniques,
#                   try "sort -u" rather than "sort | uniq".
#
#                   To reverse the line ordering, see my "tailflip".
#
#    Dependencies:  awk

#  CHANGE LOG
#  2011-01-16  First version: amazing one-liner.

# _______________     ::  BEGIN  Script ::::::::::::::::::::::::::::::::::::::::

inf=${1:-'-'}
#         ^stdin is default so that we can pipe in stuff.

awk '!x[$0]++' $inf

exit 0
# _______________ EOS ::  END of Script ::::::::::::::::::::::::::::::::::::::::