UNIX for Dummies Questions & Answers

Hi all,

I have a file that contains a list of codes (shown below).
I want to 'uniq' the file using only the first field. Anyone know an easy way of doing it?

Cheers,

Dave

##### Input File #####
1xr1 1xws 1yxt 1yxu 1yxv 1yxx 2o3p 2o63 2o64 2o65
1xr1 1xws 1yxt 1yxv 1yxx 2o3p 2o63 2o64 2o65
1xr1 1yxt 1yxv 1yxx 2o3p 2o63 2o64 2o65
1y8y 2c68 2c69 2c6i 2c6k 2c6m 2c6o
1y8y 2c69 2c6i 2c6k
1zlt 2br1 2brb 2brn 2bro 2c3k 2cgu 2cgv 2cgx
1zlt 2br1 2brb 2brn 2bro 2cgu 2cgv 2cgx
1zlt 2br1 2brb 2brn 2bro 2cgv 2cgx
1zlt 2br1 2brb 2brn 2bro 2cgx
1zlt 2br1 2brb 2bro

##### Desired Output File #######
1xr1 1xws 1yxt 1yxu 1yxv 1yxx 2o3p 2o63 2o64 2o65
1y8y 2c68 2c69 2c6i 2c6k 2c6m 2c6o
1zlt 2br1 2brb 2brn 2bro 2c3k 2cgu 2cgv 2cgx

Yes:

Code:

awk '!x[$1]++' filename

Use nawk or /usr/xpg4/bin/awk on Solaris.

Thanks for the quick response radoulov.
It works a treat!

The neat nawk solution will not always provide the same solution independent of line ordering though...

something like:

Code:

awk '{if ( length($0) > length(a[$1]) ) {a[$1]=$0}} END {for (i in a){print a[i]}}' file

will ensure you get the longest line (if that is a requirement).

Tytalus

Can you pls explain how it works..whats $1 and $0 and how does it work..Thanks a bunch!

simply it would be like...

uniq -w 4 filename

note: the catch here is that assumes your first feild would be always 4 :-)

-ilan

... and that the file is sorted.
Note that both awk solutions will work even if the file is not sorted
(as far as the requirement is the uniqueness of the first field).

P.S. Connot check right now if the w option is for the GNU version only.