perl -pe 's/(?<!\n)\n# file/\n\n# file/g' record_file

[download]

I don't see how that is supposed to work. The -p flag creates a while(<>) loop around the code specified for the -e flag(with print; as the last line in the while loop). The s/// operator in your code is going to operate on the $_ variable, and the diamond operator(<>) will assign each line in the file to $_ one line at a time.

As far as I can tell, at some point $_ will be equal to the string "# file\n", and the previous string will have been "hello world\n" (i.e. not "\n" as desired). Your regex is looking for "\n# file" preceded by a "\n". First, because it seems to me that the diamond operator will produce the line "# file\n", your regex won't match because there is no "\n# file" in that line. Second, it looks to me like you are doing a negative lookbehind beyond the start of the string. How is that supposed to work?

In reply to Re^2: Adding back missing newlines between records by 7stud
in thread Adding back missing newlines between records by puterboy

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.