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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

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mhddfs(1)						      General Commands Manual							 mhddfs(1)

NAME
mhddfs - The driver combines a several mount points into the single one. SYNOPSIS
mhddfs /dir1,/dir2[,/path/to/dir3] /path/to/mount [-o options] mhddfs /dir1 dir2,dir3 /mount/point [-o options] ... fusermount -u /path/to/mount fstab record example: mhddfs#/path/to/dir1,/path/to/dir2 /mnt/point fuse defaults 0 0 mhddfs#/dir1,/dir2,/dir3 /mnt fuse logfile=/var/log/mhddfs.log 0 0 OPTIONS
with an -o option1,option2... you can specify some additional options: logfile=/path/to/file.log specify a file that will contain debug information. loglevel=x 0 - debug messages 1 - info messages 2 - standard (default) messages mlimit=size[m|k|g] a free space size threshold If a drive has the free space less than the threshold specifed then another drive will be choosen while creat- ing a new file. If all the drives have free space less than the threshold specified then a drive containing most free space will be choosen. Default value is 4G, minimum value is 100M. This option accepts suffixes: [mM] - megabytes [gG] - gigabytes [kK] - kilobytes For an information about the additional options see output of: mhddfs -h DESCRIPTION
The file system allows to unite a several mount points (or directories) to the single one. So a one big filesystem is simulated and this makes it possible to combine a several hard drives or network file systems. This system is like unionfs but it can choose a drive with the most of free space, and move the data between drives transparently for the applications. While writing files they are written to a 1st hdd until the hdd has the free space (see mlimit option), then they are written on a 2nd hdd, then to 3rd etc. df will show a total statistics of all filesystems like there is a big one hdd. If an overflow arises while writing to the hdd1 then a file content already written will be transferred to a hdd containing enough of free space for a file. The transferring is processed on-the-fly, fully transparent for the application that is writing. So this behaviour simu- lates a big file system. WARNINGS The filesystems are combined must provide a possibility to get their parameters correctly (e.g. size of free space). Otherwise the writing failure can occur (but data consistency will be ok anyway). For example it is a bad idea to combine a several sshfs systems together. Please read FUSE documentation for a further conception. COPYRIGHT
Distributed under GPLv3 Copyright (C) 2008 Dmitry E. Oboukhov <dimka@avanto.org> February 2008 mhddfs(1)
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