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Full Discussion: Adding new line to file
Top Forums Shell Programming and Scripting Adding new line to file Post 302903136 by lazy_bear on Sunday 25th of May 2014 05:54:43 AM
Old 05-25-2014
Quote:
Originally Posted by Don Cragun
Showing us the work that you have done is good. But, just showing us a script that is not working without also showing us sample input and expected output makes it hard to guess at all of the things that might be wrong in your script. The script you have shown us seems to be a strange mix of shell and awk statements.

Please tell us what operating system you're using, tell us what shell you're using, show us some sample input, and show us the exact output you want to produce from that sample input.
@Don Cragun, thank you for remind me about the manner Smilie.
my job is rarely relate to scripting and I just make this script due to my colleague request on yesterday so I just try to use what I know and google what I don't. That's why my script look like a bunch of scraps Smilie.
by the way, my OS is Linux Redhat, I'm using Perl which included. My script is used for comparing 2 file which contain lines with this info:
Code:
 coordinate_x coordinate_y  variable_name  value_1 value_2...

My expect output file which contains all lines with same values, another output file contain lines with different values. Currently, I use loop for comparing 2 file but it's seem take time cause input files having few thousand lines each, so I'm finding another way.

Quote:
Originally Posted by Aia
By the way, perl has an special variable `$.' (that's $ and period) which might help you read the specific line of a file without resorting to making calls to the external head and tail.

So instead of $line1= `head -tmp1 file1| tail -1`;

maybe something like:
Code:
open my $fh, '<', $file1 or die "$file1: $!";

my $cntl = 1; # or whatever you want
my $line;
while( <$fh> ) {
    if( $. == $ctl ) { 
        $line = $_;
        last;
    }
}
close $fh

# now you can use $line here

@Aia: thank you so much for your hint. it's just where I stuck Smilie.
Thank you for the suggestion, hope it can reduce the script running time.
 

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