Remove duplicate rows of an un-sorted file based on a single column

perl -ane 'print unless $x{$F[0]}++' infile > outfile
F[0] filters using first word. $F[1] - 2nd, and so on.

3
By: depesz
2010-12-15 17:46:22

1 Alternatives + Submit Alt

  • The command (above) will remove any duplicate rows based on the FIRST column of data in an un-sorted file. The '$1' represents a positional parameter. You can change both instances of '$1' in the command to remove duplicates based on a different column, for instance, the third: awk '{ if ($3 in stored_lines) x=1; else print; stored_lines[$3]=1 }' infile.txt > outfile.txt Or you can change it to '$0' to base the removal on the whole row: awk '{ if ($0 in stored_lines) x=1; else print; stored_lines[$0]=1 }' infile.txt > outfile.txt ** Note: I wouldn't use this on a MASSIVE file, unless you're RAM-rich ;) **


    4
    awk '{ if ($1 in stored_lines) x=1; else print; stored_lines[$1]=1 }' infile.txt > outfile.txt
    dopeman · 2010-12-15 17:08:47 0

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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