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Full Discussion: Confusing sed error message
Top Forums Shell Programming and Scripting Confusing sed error message Post 303027482 by Scrutinizer on Sunday 16th of December 2018 04:26:14 PM
Old 12-16-2018
Quote:
Originally Posted by Ralph
[..]
--- Post updated at 03:15 PM ---

Actually, what I'm trying to do is remove duplicate pairs from a file like this:
Code:
==: dir1/dir2/file1 dir3/dir4/file2
==: dir5/dir6/file3 dir1/file4
==: dir3/file5 dir3/file6
==: dir1/file4 dir5/dir6/file3
==: dir3/dir4/file2 dir1/dir2/file1
==: dir3/file6 dir3/file5

I find out it doesn't really work if I redirect the file into a while-loop that uses read to read a line, like this:
Code:
while read $LINE ; do
   swap column 2 with column 3
   remove swapped line from file (using sed)
done < file

I got the idea because while read works line by line from the beginning of the file the swapped line is always located behind the other one so if I remove it read will never see it. But apparently the entire original file is still available to read no matter what I remove.

Is there is a better approach?
Assuming the fields in your input file are whitespace separated, you could try this approach:
Code:
awk '!A[$2,$3]++ && !A[$3,$2]++' file

These 2 Users Gave Thanks to Scrutinizer For This Post:
nezabudka Ralph
 

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LEARN ABOUT OSX

opendiff

opendiff(1)						    BSD General Commands Manual 					       opendiff(1)

NAME

     opendiff -- Use FileMerge to graphically compare or merge file or directories

SYNOPSIS

     opendiff file1 file2 [-ancestor ancestorFile] [-merge mergeFile]
     opendiff dir1 dir2 [-ancestor ancestorDirectory] [-merge mergeDirectory]

DESCRIPTION

     opendiff is a command line utility that provides a convenient way to launch the FileMerge application from Terminal to graphically compare
     files or directories.  If FileMerge is already running, opendiff will connect to that running instance for the new comparison.  opendiff
     exits immediately after the comparison request has been sent to FileMerge.

     opendiff and FileMerge can be used to compare two files file1 and file2 or to compare two directories dir1 and dir2.

     If the -ancestor flag is given, FileMerge will compare the two files or directories to a common ancestor.	This is useful if two people inde-
     pendently modify copies of a single original file or directory.

     FileMerge lets you merge two files or directories together to create a third file or directory.  To see the contents of a merged file, drag
     the splitter bar at the bottom of FileMerge's file comparison window.  The contents of the merged file can be directly edited within File-
     Merge.  After editing, the merged file can be saved to the file (or into the directory) specified with the Fl merge flag.	If a destination
     is not specified with the -merge flag, FileMerge will ask for a destination file or directory when you try to save a merged file.

     For further information, please consult the Help information available from the FileMerge application.

FILES

     /Developer/Applications/Utilities/FileMerge.app

     opendiff and FileMerge are installed as part of the Mac OS X Developer Tools.

SEE ALSO

     diff(1), diff3(1), cmp(1)

Mac OS X							  August 3, 2004							  Mac OS X
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