The following links might help you.

https://www.cs.tut.fi/~jkorpela/perl/regexp.html

https://affy.blogspot.in/p5be/ch10.htm

Hi there!

As always, there are multiple ways of doing anything in informatics and so it happens in bioinformatics.

For this specific problem, you can use a regex function or you can use a predefined perl function named ord, that returns the ASCII code of any given symbol. 

The ASCII code for µ symbol is 230 (http://www.theasciicode.com.ar/extended-ascii-code/lowercase-letter-mu-micro-sign-micron-ascii-code-230.html).

I am not sure why, in my case, µ is codified as 194, I guess it must be due to the encoding of my computer. Anyway, I will 194 as an identifier for the µ symbol. 

Here I show you an implementation in perl of both, using regex and using perl ord and the 194 ASCII code

 Imagine your data is in a file "test.txt" containing several lines like:

************************** 

x=12

µ=12,13

************************** 

Now, pass this file as an argument to a perl script containing the following code.

************************** 

#!/usr/bin/perl

use strict;

use warnings;

my $file = $ARGV[0];

open("FILE", $file);

while () {

chomp;

my $line = $_;

print "READING: ".$line."\n";

if ($line =~ /.*µ.*/) { print "FOUND using regex!!\n"; }

my @array_line = split("=", $line);

for (my $i=0; $i < scalar @array_line; $i++) {

my $tmp = ord($array_line[$i]); ## ord: basic perl function: returns number given ASCII

print "ASCI: ".$tmp."\t Symbol: $array_line[$i]\n";

if ($tmp == 194) { print "Symbol $array_line[$i] found using perl ord!!\n"; print $line."\n"; }

}

}

close (FILE);

**************************