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<H4>By Jim Dennis, Ben Okopnik, Dan Wilder, Breen, Chris, and the Gang,
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<H3 align="left"><img src="../../gx/dennis/qbubble.gif"
height="50" width="60" alt="(?) " border="0"
>Search and Replace Without Breaking Permissions</H3>
<p><strong>From Peagler Kelley
</strong></p>
<p align="right"><strong>Answered By Ben Okopnik
<br></strong></p>
<!-- ::
Search and Replace Without Breaking Permissions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
:: -->
<P><STRONG>
Hi,
</STRONG></P>
<P><STRONG>
I am doing a global search and replace on some files via a unix script. I
use the sed command (saving a copy of the original in $file.old) like so:
</STRONG></P>
<P><STRONG><CODE>
sed "s/$INPUT_TXT/$OUTPUT_TXT/g" $file &gt; $NEW_FILE
</CODE></STRONG></P>
<P><STRONG>
Then I perform a diff on the original file ($file) and the new file
($NEW_FILE) and redirect the output to <TT>/dev/null</TT>. If there is a difference
between the two files, then I move the new file to the old file.
Unfortunately I end up changing the permissions on all the files in the
directory, depending on whatever default umask is set. Is there a way that
I can either 1) find out what the permissions of the original file are and
change them accordingly to the new file, or 2) move the new file to the
original file while keeping the permissions of the old file?? Please let me
know. Thanks!!
</STRONG></P>
<BLOCKQUOTE><IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
HEIGHT="28" WIDTH="50" BORDER="0"
> [Ben]
"sed" is not the best tool for "in-place editing" of the kind you want to
do - all you really want is to change the data in the file, right? Perl
offers a solution that reduces it from a three-step process
(change/diff/move) to one:
</BLOCKQUOTE>
<blockquote><code><font color="#000033"><br>perl -i -wpe 's/$INPUT_TXT/$OUTPUT_TXT/g' $file
</font></code></blockquote>
<BLOCKQUOTE>
That's it. The editing is done in the file itself; the permissions are
unchanged. No muss, no fuss, no greasy aftertaste.
</BLOCKQUOTE>
<!-- sig -->
<P><STRONG><IMG SRC="../../gx/dennis/qbub.gif" ALT="(?)"
HEIGHT="28" WIDTH="50" BORDER="0"
>
I agree with you. I wanted to use perl, but the person who I'm creating this
for does not know perl and will be responsible for supporting it. I like your
quick, dirty solution and I may force them to use it just because it's
easier
<IMG SRC="../../gx/dennis/smily.gif" ALT=";-)"
height="24" width="20" align="middle">. Thanks!
</strong></p>
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<H5 align="center">This page edited and maintained by the Editors
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<a href="http://www.linuxgazette.com/copying.html"
>Copyright &copy;</a> 2001
<BR>Published in issue 66 of <I>Linux Gazette</I> May 2001</H5>
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