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PODynamic Perl find and replace using grep inside backticks
 

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  1. PODynamic Perl find and replace using grep inside backticks
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    <p>I am trying to do a dynamic search and replace with Perl on the command line with part of the replacement text being the output of a grep command within backticks. Is this possible to do on the command line, or will I need to write a script to do this?</p> <p>Here is the command that I thought would do the trick. I thought that Perl would treat the backticks as a command substitution, but instead it just treats the backticks and the content within them as a string:</p> <pre><code>perl -p -i -e 's/example.xml/http:\/\/exampleURL.net\/`grep -ril "example_needle" *`\/example\/path/g' `grep -ril "example_needle" *` </code></pre> <p>UPDATE:</p> <p>Thanks for the helpful answers. Yes, there was a typo in my original one-liner: the target file of grep is supposed to be *.</p> <p>I wrote a small script based on Schewrn's example, but am having confusing results. Here is the script I wrote:</p> <pre><code> #!/usr/bin/env perl -p -i my $URL_First = "http://examplesite.net/some/path/"; my $URL_Last = "/example/example.xml"; my @files = `grep -ril $URL_Last .`; chomp @files; foreach my $val (@files) { @dir_names = split('/',$val); if(@dir_names[1] ne $0) { my $url = $URL_First . @dir_names[1] . $URL_Last; open INPUT, "+&lt;$val" or die $!; seek INPUT,0,0; while(&lt;INPUT&gt;) { $_ =~ s{\Q$URL_Last}{$url}g; print INPUT $_; } close INPUT; } } </code></pre> <p>Basically what I am trying to do is:</p> <ol> <li>Find files that contain $URL_Last.</li> <li>Replace $URL_Last with $URL_First plus the name of the directory that the matched file is in, plus $URL_Last.</li> <li>Write the above change to the input file without modifying anything else in the input file.</li> </ol> <p>After running my script, it completely garbled the HTML code in the input file and it cut off the first few characters of each line in the file. This is strange, because I know for sure that $URL_Last only occurs once in each file, so it should only be matched once and replaced once. Is this being caused by a misuse of the seek function?</p>
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    1. COIf I am not mistaken, `grep -ril "example_needle"` is lacking a target file, as you cannot print a file name on stdin. Perhaps you should just try to explain what you are trying to do instead.
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    2. COtake the time to make a small sample file that you can edit into your question, and show what you need as output. Otherwise, we're just guessing. Good luck.
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    3. COSeek is definitely unnecessary, since the file handle position will already be at the beginning when you open the file. As for your problem description, you will find that 1 example is worth more than 10 essays. I assume you want to, for example, open `foo/bar.html`, replace `/example/example.xml` with `http://examplesite.net/some/path/foo/example/example.xml`?
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