Just picked up a little bit of sed kungfu today while pairing with jeff.

In-place editing with “-i”

If you want to do in-place editing of a file, you can pass the -i option to sed. Let’s say we have the following file:

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sed is cool

With:

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$ sed -i /path/to/file -e 's/cool/awesome/'

We get:

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sed is awesome

So how do i acheive this previously ?? This is embarrassing, it used to be like this:

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$ cat /path/to/file | sed 's/cool/awesome' > /path/to/file.new
$ mv /path/to/file.new /path/to/file

Replacing only lines matching pattern

Let’s say you have the following file:

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Vim is really cool,
& sed is cool as well.

We want to replace only the line with the occurrence of “sed”. We can acheive it using the script command /<pattern>/s/<original-text>/<replacement-text>, just like this:

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sed -e '/sed/s/cool/awesome/' /path/to/file

This is what we get in stdout:

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Vim is really cool,
& sed is awesome as well.

Happy Sed-ing :)