I recommend looking at perlre on perldoc.perl.org first. There are two main operators m/ and s/ for match and substitute. It's a lot to learn, but no time like the present. To take an example in detail: I want to change all digits into X in the string $s: 
$s =~ s/\d/X/g;

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The =~ announces a regex operator, in this case s for substitute. '/' are the most common delimiters. You need two for match and three for substitutions. \d is the digit token, X is literal and the g at the end is for match all occurrences.

There are lots of tokens and modifiers. In principle a complex matching is achieved simply by concatenating terms together e.g. ^\d+\S requires the \d+ to start at the beginning and the \S would be a non-space after the digits -- so not a digit which would have been consumed by the \d+ term.

Bon voyage on your journey through perlre!

One world, one people

In reply to Re: How to search an substring and eliminate before and after the substring by anonymized user 468275
in thread How to search an substring and eliminate before and after the substring by Murali_Newbee

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