topic Re: Perl - Simple field delimeter based extraction in Operating System - Linux

Perl - Simple field delimeter based extraction

Daavid Turnbull — Sun, 31 Jul 2005 19:20:02 GMT

If I had my Camel book to hand I would hope that I could nut this one out. Basically I need to extract a field, delimeted by '|' (vertical bars) from a single line and use it as a key to grep a line from an other file.

The line might look like:

field number one|field number two|field 3 etc.

I am assuming that this can be done with a simple expression... as opposed to breaking up the string using tokens but my mind is blank as to how this may look syntax wise at the moment.

Re: Perl - Simple field delimeter based extraction

H.Merijn Brand (procura — Mon, 01 Aug 2005 01:36:01 GMT

Sure. Easy

my %keys;
open my $key_file, "while (<$key_file>) {
chomp;
# assuming the key is the first field
my ($key, @fields) = split m/\|/, $_, -1;
$keys{$key} = [ @fields ];

# alternatively, if you don't need the other
# fields, and field 5 is your key
$keys{(split /\|/, $_, -1)[4]}++;
}
close $key_file;

# Now parse the other file(s)
while (<>) {
my @fields = split m/\|/, $_, -1;
# See if field 3 (1-based, perl is 0-based)
# exists in your keys
exists $key{$fields[2]} or next;
# line accepted, process
}

Enjoy, Have FUN! H.Merijn

Re: Perl - Simple field delimeter based extraction

Muthukumar_5 — Mon, 01 Aug 2005 01:42:59 GMT

You can try as,

echo "hi|bye|see|you" | perl -ne '@keys=split(/\|/); print @keys;'

Use @keys to grep the line in a file.

hth.

Re: Perl - Simple field delimeter based extraction

Muthukumar_5 — Mon, 01 Aug 2005 01:52:19 GMT

You can try with a script also as,

#!/usr/bin/perl

# single Line
$_="first|second|third|four|fifth";
@keys=split (/\|/);
$FILE="/tmp/test.log";

open(FH,$FILE) || die "Can not open file: $!";

while () {

foreach $key (@keys)
{
print $_ if ( m/$key/);
}
}

# end #

hth.

Re: Perl - Simple field delimeter based extraction

Daavid Turnbull — Mon, 01 Aug 2005 18:54:38 GMT

Thanks for the responses.

All these work and work remarkably well.

I will assign points after I have coded and tested based on what I have learned.

Re: Perl - Simple field delimeter based extraction

Daavid Turnbull — Wed, 03 Aug 2005 00:32:06 GMT

My app was a little more convoluted but what I learned from your posts was spot on. I assigned 10 points each.

Re: Perl - Simple field delimeter based extraction

Daavid Turnbull — Wed, 03 Aug 2005 00:33:18 GMT

Problem solved. Next I have some xml to parse with Perl so I may end up asking more questions shortly.