Re: [clug-talk] Perl regular expressions ?

[Michael Gale]

AH HA ...
I got it figured out :)
Here is the code, I will comment it so other people can know:
#!/usr/bin/perl -w
while(<STDIN>)
{
my($input) = $_; #Read strings in on the command line
chomp($input);   #Removes trailing line feed
if ($input =~ "DONE")  #If string is contains DONE exit
        {
                exit;
        }
print "#################\n";
print "### OUTPUT IS ###\n";
print "#################\n";
print "### ";
print $input =~ /(\d+);(\d+);(\d+);(\d+)/;
## Look for a pattern that matchs number;number;number;number
## \d means match a number
## + means any amount of numbers
## /()/ assigns the match to $1,$2 and so on
print "\n";
print "\$1 = $1\n";
print "\$2 = $2\n";
print "\$3 = $3\n";
print "\$4 = $4\n";
print "\n";
print "#################\n";
print "\n\n\n";
}
So when I run the script is passed it "Memory Usage: 1234;678;000;4567" 
which is sort of like the out put from a nagios memory check on windows 
boxes ;)

Now if you simple print:
print $input it will equal "Memory Usage: 1234;678;000;4567"
print $input =~ /(\d+);(\d+);(\d+);(\d+)/; it will produce "12346780004567"
which may be confusing ... because what happens to $1 ? Remember because 
"/(pattern)/" is supposed to assign the match to a $1 and $2 and so on. 
It actually does ... it just gets printed with out any spaces.

If you print $1,$2,$3,$4 you will see how they are divided:
--snip--
[EMAIL PROTECTED] Desktop]$ ./rgperl
Memory Usage: 1234;678;000;4567
#################
### OUTPUT IS ###
#################
### 12346780004567
$1 = 1234
$2 = 678
$3 = 000
$4 = 4567
#################
--snip--
Hope this helps other people figure out where the arguments can come from :)
Michael.

Michael Gale wrote:
Hello,
I wrote this little test script to my regular expressions:
#!/usr/bin/perl -w
while(<STDIN>)
{
my($input) = $_;
chomp($input);
#my($input,$check) = $input =~ m/(.*\|)(.*)$/;
if ($input =~ "DONE")
        {
                exit;
        }
$input =~ /.*(\d+)/;
print "#################\n";
print "### OUTPUT IS ###\n";
print "#################\n";
print "### ";
print $_;
print "\n";
print "#################\n";
print "\n\n\n";
}
Michael.
Michael Gale wrote:
Hello,
I am going to start playing around with perl regular expressions but 
first have some questions I am hoping someone on the list can answer ?

1. Can I test them from the command line ?
echo "some string of text" | perl place_regular_expression_here
2. How would I go about producing arguments are out put, for example:
echo "Memory Usage: 25% used warning 75%" | perl 'Memory.Usage:.\d+'
The about would produce "Memory Usage: 25" but I only want to output 
the 25 but I also need to make sure that the first part contains 
"Memory Usage:" ?

Thanks.
Michael.
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