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Added example of backreferences in Perl one-liners.

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Shawn Milochik 2015-07-25 14:33:00 -04:00
parent 24832fe2e1
commit 400a91c979
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@ -193,6 +193,32 @@ Notes:
perl -pi.bak -e 's/old-string/new-string/g' my-files-*.txt
```
- To strip URLs from surrounding HTML:
```sh
$ cat example.html
Some text <a href="http://example.com/roar.mp3">Lion roar</a> So cool!<br/>
More stuff <a href="http://example.com/bird.mp3">Bird call</a>Pretty<br/>
No link on this line.
Some text <a href="http://example.com/crickets.mp3">Crickets</a>Relaxing.<br/>
Some text <a href="http://example.com/beach.mp3">Ocean waves.</a>Meditate!<br/>
More junk.
$ perl -ne 'print if s/^.*href="([^"]+)".*$/$1/' example.html
http://example.com/roar.mp3
http://example.com/bird.mp3
http://example.com/crickets.mp3
http://example.com/beach.mp3
# Make a script to download all the files.
$ perl -ne 'print if s/^.*href="([^"]+)".*$/wget $1/' example.html > download.sh
$ cat download.sh
wget http://example.com/roar.mp3
wget http://example.com/bird.mp3
wget http://example.com/crickets.mp3
wget http://example.com/beach.mp3
```
- To rename many files at once according to a pattern, use `rename`. For complex renames, [`repren`](https://github.com/jlevy/repren) may help.
```sh
# Recover backup files foo.bak -> foo: