awk multiple field separators.

Using multiple field separators with awk and perl to convert "," to a newline.

Example:

echo "100(txt),528(smbw),529(smbt),530(smbn),10115(smbs)"|\
 perl -pe 's/,/\n/g'
100(txt)
528(smbw)
529(smbt)
530(smbn)
10115(smbs)

Using awk to just print the text between ().

echo "100(txt),528(smbw),529(smbt),530(smbn),10115(smbs)"|\
 perl -pe 's/,/\n/g'|\
 awk -F"[()]" '/smb/{print $2}'
smbw
smbt
smbn
smbs

Using awk to just print the text between [].

awk -F'[][]' and awk -F'[[]]' will not work.

Match IP numbers with regex.

Print any IP address talking on port 21 in coming or out going.

Change the port number to any port that needs to be matched.

netstat -na | perl -ne '/((\d{1,3}\.){4}21)/ &&  print ;'

 

Perl script options

Using getopt in perl scripts.
Sample code

#!/usr/bin/perl
#-------------------------------------------------------------------------
#       Using getop
#-------------------------------------------------------------------------
use Getopt::Std;
getopt('cw');
my @op = `./x.sh -c $opt_c -w $opt_w`;
foreach (@op)
{
        #printf "-c %s\t-w %s\n", $opt_c,$opt_w;
        print $_;
}

Output

./x.pl -c 3 -w 55

in ./x.sh.sh : -c 3 -w 55

-c 3

-w 55

or

my %options=();

#Pre set default values 

my $critv=95;
my $warnv=85;
getopts("c:w:", \%options);
$critv = $options{c} if defined $options{c};
$warnv = $options{w} if defined $options{w};

This method won't report an error if an option is emitted.

Perl. Replace text in file.

Substitute text in a file in-situ

perl -i -pe 's/1234/4321/g' filename

-i edits file in-situ.
-p loops through each filename and prints out each line.

Convert Upper case to lower case

perl -i -pe 'tr/A-Z/a-z/' x

Perl command line.

Using multiple perl commands on the command line.

perl -n -e 'perl cmd;'\
-e 'perlcmd'

Invoke the split command

perl -n -a -e 'cmd'

-n Places a loop around the command line.