The UNIX and Linux Forums  
Hello and Welcome from United States to the UNIX and Linux Forums! Thank You for Visiting and Joining Our Global Community.

Go Back   The UNIX and Linux Forums > Top Forums > Shell Programming and Scripting
Reload this Page duplicate line in a text file
.
google unix.com

Forums Register Forum RulesLinksAlbums FAQ Members List Calendar Search Today's Posts Mark Forums Read



Thread: duplicate line in a text file
View Single Post in the UNIX and Linux Forums - Click on the Thread or Permalink to View Entire Thread -->
  #2 (permalink)  
Old 04-25-2008
era era is offline Forum Advisor  
Herder of Useless Cats (On Sabbatical)
  
 

Join Date: Mar 2008
Location: /there/is/only/bin/sh
Posts: 3,652
Code:
perl -ne '$l = lc(); print if $m{$l}++; ' file
lc returns the specified string in lowercase; in this case, with no parameter, it defaults to the current input line. $m{$l} is the count of number of times we have seen $l; if it's nonzero, it's a duplicate, so we print it.
Last edited by era; 04-25-2008 at 02:50 PM.. Reason: Add explanation