Heres one way. 
use strict;
use warnings;

my %seen;
while ( <DATA> ) {
 print unless $seen{(split /\|/)[0]}++;
}

__DATA__
123|abc
123|cde
234|efg
456|hij

[download]

-enlil

In reply to Re: how to remove duplicate based on the first column value by Enlil
in thread how to remove duplicate based on the first column value by tariqahsan

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