Hi, you want to use a substitution regex operator. the match operator is described as m//, this is the operator you have used. The substition operator is described s///.

The pattern you wish to match goes in the first section as per a normal match, the pattern you wish to replace in the second section. You can use parentheses in the first section to capture the matched pattern and reuse it in the second section within the special variables $1 through $9

if ($_ =~ /start ux/){
                        print "#$_";
                        }

[download]

(assuming the whole line is a pattern match) becomes...

s/(pattern)/#$1/;

[download]

if you wanted to insert an octothorpe if the pattern matches anywhere in the line, you could have your regex match the whole line if part of it matches...

s/^(.*(pattern).*)$/#$1/;

[download]

regex operates on the $_ variable, and substitution matching is an 'if' operation in itself. In this case the parentheses match in subsequential order from first open through to second open (pattern matches $2). The outer characters say, anything matches.

s/(Coy)/$1ote/;

In reply to Re: Write to existing file with character insert by Don Coyote
in thread Write to existing file with character insert by Mark.Allan

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.