Update: Sorry, I just realised, this is in essence what has been suggested by 1Nf3 right at the beginning of this thread ... apologies!

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

Personally, I like the following two-liner because it is concise, simple and flexible (as illustrated, it will also work with an arbitrary number of indented lines):
( my $line = ( join "", <>  ) ) =~ s/\n\s+//g;    
print $line;



______DATA_______

firstline54324563213612531436436463246324634
         secondlidfndsfdsfdsfd
         thirdlinedsfsdf
firstline54324563213612531436436463246324634
         secondlidfndsfdsfdsfd
         thirdlinedsfsdf
         fourthlinedsfsdf
         fifthlinedsfsdf

_____OUTPUT______

firstline54324563213612531436436463246324634secondlidfndsfdsfdsfdthird
+linedsfsdf
firstline54324563213612531436436463246324634secondlidfndsfdsfdsfdthird
+linedsfsdffourthlinedsfsdffifthlinedsfsdf

[download]
Essentially, it compounds the entire data file into a single string from which any occurrence of \n\s+ is then removed. The latter string sequence is the one which occurs at every line end except for those line ends before a firstline.

Hope this helps.

Best regards -

Pat

In reply to Re: Appending lines starting with white space to the previous line by pat_mc
in thread Appending lines starting with white space to the previous line by ashok13123

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.