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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 XFREE86

pam_motd

PAM_MOTD(8)							 Linux-PAM Manual						       PAM_MOTD(8)

NAME

       pam_motd - Display the motd file

SYNOPSIS

       pam_motd.so [motd=/path/filename]

DESCRIPTION

       pam_motd is a PAM module that can be used to display arbitrary motd (message of the day) files after a successful login. By default the
       /etc/motd file is shown. The message size is limited to 64KB.

OPTIONS

       motd=/path/filename
	   The /path/filename file is displayed as message of the day.

       noupdate
	   Don't run the scripts in /etc/update-motd.d to refresh the motd file.

MODULE TYPES PROVIDED

       Only the session module type is provided.

RETURN VALUES

       PAM_IGNORE
	   This is the only return value of this module.

EXAMPLES

       The suggested usage for /etc/pam.d/login is:

	   session  optional  pam_motd.so  motd=/etc/motd

SEE ALSO

       motd(5), pam.conf(5), pam.d(5), pam(7), update-motd(5)

AUTHOR

       pam_motd was written by Ben Collins <bcollins@debian.org>.

Linux-PAM Manual						    09/19/2013							       PAM_MOTD(8)
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