PERL Beginners - last entry in a file

Author

last entry in a file

Paul 0403

2008-01-17, 10:02 pm

Is there a quick and easy way in perl to get the last entry in a file
for a specific value

For example If I have the following data in a file

<len>1<\len>
<type>int<\type>
<len>2<\len>
<type>int<\type>
<len>3<\len>
<type>int<\type>

I would like to get the line <len>3<\len>.

Please keep in mind that the data in the file is only a sample and it
will not alwasy be the second line from the bottome :-)

I know I can read the file and keep track via a flag of where I am in
the file but this seems way to over-kill. I was hoping for some nice
easy grep like command.

Thanks in advance

reader@newsguy.com

2008-01-17, 10:02 pm

paul_0403@yahoo.com writes:

> Please keep in mind that the data in the file is only a sample and it
> will not alwasy be the second line from the bottome :-)
>
> I know I can read the file and keep track via a flag of where I am in
> the file but this seems way to over-kill. I was hoping for some nice
> easy grep like command.

If its the data in the len lines then you can just find it with a
regex and the last find will be the one you get.

while (<FILE> ){
if (/regex/){
$var = $_;
}
}
print $var . "\n";

The value of $var will change at each hit, but if you only want the
last one then thats what will be in var at the print

Randal L. Schwartz

2008-01-17, 10:02 pm

>>>>> "paul" == paul 0403 <paul_0403@yahoo.com> writes:

paul> Is there a quick and easy way in perl to get the last entry in a file
paul> for a specific value

paul> For example If I have the following data in a file

paul> <len>1<\len>
paul> <type>int<\type>
paul> <len>2<\len>
paul> <type>int<\type>
paul> <len>3<\len>
paul> <type>int<\type>

paul> I would like to get the line <len>3<\len>.

paul> Please keep in mind that the data in the file is only a sample and it
paul> will not alwasy be the second line from the bottome :-)

You haven't stated the problem sufficiently. How come it isn't

<type>int<\type>

What does "last entry for a specific value" mean? To me, that's
the last entry in the file. :) What does "specific" mean, specifically?

By the way, is this some bizarro mirror XML, or do you really mean
<type>int</type>
?

--
Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
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