topic Re: perl delete help in Operating System - Linux

perl delete help

Shaf_1 — Mon, 11 Oct 2004 13:03:44 GMT

I have some files that I need to delete the header information. I am new to Perl and have no idea on how to approach this. I have attached an example of the files I am working with. I need to be able to delete the header information starting from 'Received:' all the way up to 'DeliveredDate:'. Can anyone please help? Thanks

Re: perl delete help

John Poff — Mon, 11 Oct 2004 16:01:35 GMT

Hi,

Here is one way to do it. Create a Perl script that will match a range of lines and skip them, otherwise printing the lines. Something like this:

#!/usr/bin/perl

# noheader.pl

while (<>) {
if (/Received:/ .. /DeliveredDate:/) {
next;
} else {
print;
}
}

Now, just run it like this:

./noheader.pl <159191.txt

and it should just print the text you need.

Of course, there are even shorter ways to do it. After I played with this for a bit I figured out that this would also work:

while (<>) {
print unless (/Received:/ .. /DeliveredDate:/);
}

JP

Re: perl delete help

Shaf_1 — Mon, 11 Oct 2004 21:46:24 GMT

Thank you so much for the help. However, I have a couple of more questions now. When the data is printed how can I save the new output in the same file?

In perl can I have the script to run for over 500 different files at once? Is there a way to avoid entering the file name for every file?

Re: perl delete help

John Poff — Tue, 12 Oct 2004 09:19:04 GMT

Hi,

You can use the '-i' option from the Perl command line to edit the file in place. Something like this should work:

perl -i -n -e 'print unless (/Received:/ .. /DeliveredDate:/);' 159191.txt

There are a couple of ways to handle it with a bunch of files. One way would be to put the line above into a small shell script:

for f in *.txt
do
perl -i -n -e 'print unless (/Received:/ .. /DeliveredDate:/);' $f
done

You could also use the file handling machinery inside of Perl and do it in a single script.

JP

Re: perl delete help

Shaf_1 — Wed, 13 Oct 2004 19:22:26 GMT

Hello,

I put the following in a script as you suggested:

for $f in *.txt
do
perl -i -n -e 'print unless (/Received:/ .. /DeliveredDate:/);'$f
done

I get this error message:

'Missing $ on loop variable at test.pl line 1.'

Am I doing something wrong? Do I need to assign a directory where the files are located?

Thanks

Re: perl delete help

John Poff — Wed, 13 Oct 2004 19:51:19 GMT

Hi,

It looks like you left out the space between the last single quote and the dollar f variable.

You should be able to run this from the directory where your files are located, or else you can specify the path in the 'for' statement, like this:

for f in /some/directory/*.txt

JP

Re: perl delete help

Shaf_1 — Wed, 13 Oct 2004 23:08:48 GMT

Hello JP,

Sorry about this I have another question. Can I put this code in a .pl file:

for f in *.txt
do
'print unless(/Received:/ .. /DeliveredDate:/);' $f
done

and then run it this way:

perl -i -n -e filename.pl

I am not sure if this is legal or not.

Thanks

Re: perl delete help

Shaf_1 — Wed, 13 Oct 2004 23:25:45 GMT

Hello JP,

Please disregard my previous message. I got it to work. Thank you for all your help. You saved me!