If your data is in a simple and predictable format (i.e was generated) then a perl one-liner ought do the trick 
perl -pi.bak -e '/from stuff/ or next; ($d)=$ARGV=~/(\d\d)\.txt$/; \
                 s/from stuff/$& where thing = "$d"/' *.txt

[download]
So that will replace every line containing the string 'from stuff' in every .txt file in the current directory with 'from stuff where thing = "$d"', where $d is the last two digits of the filename. See. perlrun for info on perl's command-line options, perlre for info on perl's regular expressions and perlvar for info on the $& variable.
HTH

_________
broquaint

In reply to Re: Get filename inside each file by broquaint
in thread Get filename inside each file by Anonymous Monk

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.