Adding functionality to Perl script

[wiss]

Hi,

I am a C++ programmer and never used Perl. I am looking for help in order to add a functionality to a script, in Perl language.

Originally, the script takes 1 file input and I run it in this way: ./script.pl file1

It is designed to return specific words from that file, example:

user
admin
printer-1
user-2
server

The idea is that I need to be able to provide the script with a second input file that contains only few words, each on a new line. These words might have a "dash". Example:

printer-2
server
user-2

I will be running the script as: ./script.pl file1 file2

In return, the script should check if every word in file1 does exist in file2. If it does exist, then the script displays it.
In the example I provided above, the script should only return:

server
user-2

Here is the script I have. What's in black is the original working Perl script and what's in red is what I would like to add in Perl Language:

!/usr/bin/env perl

my ($table);

for (every value in file2)
{
read it and put it in an array of strings
}


while (<>) {
m{Hello\s+(\S+)};
if ( defined($1) and this word exists in the array ){
$table = $1;
print "$table\n"};
}
}
exit(0);

Thank you for any assistance!

[Kloschüssel]

Why modify it? You can pipe the result of script.pl to another script, preserving the old functionality:

$ script.pl file1 | grep -E 'server|user-2'

Another option would be to use awk.

[wiss]

Yep that works but sometimes file2 might have 250 words and I don't want to paste them all... I would like to have a complete script.

Thanks!

[Kloschüssel]

Then why not write a script that reads a file line after line and building up the regular expression?

$ REGEX='server|user-2'; script.pl file1 | grep -E $REGEX

The regex builder could be your perl script. If the regex becomes too big, you could cache it to a temporary file and use grep's -f switch.

[wiss]

Thanks for your feedback.

Unfortunately I wasn't able to get an output. Here is what I tried:

./script.pl file.out | grep -E 'value|s-error|user|Rules'

grep: illegal option -- e
Usage: grep -hblcnsviw pattern file . . .

and I then I tried tried:

REGEX='value|s-error|user|Rules'; ./script.pl file.out | grep -E $REGEX

grep: illegal option -- E
Usage: grep -hblcnsviw pattern file . . .

[wiss]

Is anyone able please to provide me with an Perl code as I requested above?

Thanks

[wiss]

I found out that I need to use "/usr/xpg4/bin/grep" instead of just "grep"

[Kloschüssel]

Strange, though I can confirm that there are different versions of grep around. I've here:

$ grep --version
GNU grep 2.6.3