execute VI command from bash script
 

Goal:
Execute a vi find-and-replace command and continue running bash script.

This is as close as I've gotten:
This goes trough template.conf and replaces every instance of "DOMAINNAME" with "example.com" the problem is now I still need an additional command to save the file. How can I edit and save from a bash script?

Thanks!
-Adam

Why use vi? Sed (the stream editor), does exactly what you're after. So:
does it.

Beautiful!

Thanks,
-Adam

There's nothing wrong with using vi/vim for this. In fact, the gnu version of the ex editing command is actually equivalent to "vim -es", which I think is probably easier to use than vim -ec. You can simply feed it any sequence of ex-mode commands from stdin that you want, without having to worry about special formatting or escaping or whatever.

In any case, you just need to add a "write" command to the end of the sequence to save it back to file, just as you would in interactive vi.

A similar, but lighter, command is ed. The basic syntax for most actions is pretty much identical to ex (although it doesn't have anywhere near the range and flexibility).

How to use ed:
http://wiki.bash-hackers.org/howto/edit-ed
http://snap.nlc.dcccd.edu/learn/nlc/ed.html
(also read the info page)


However, as mentioned by TB0ne, the best option for most simple edits is generally sed. sed works pipeline-style and simply runs through the file once, one line at a time, from top to bottom. So as long as the edits don't cross line boundaries, it's usually easier and more efficient.

Here are a few useful sed references:
http://www.grymoire.com/Unix/Sed.html
http://sed.sourceforge.net/grabbag/
http://sed.sourceforge.net/sedfaq.html
http://sed.sourceforge.net/sed1line.txt
http://www.catonmat.net/series/sed-one-liners-explained

vim and ed, OTOH, load the whole file into a memory buffer before editing, which makes them a bit slower, but does also allow you to operate on the whole file in random-access fashion. This makes multi-line work in particular much easier than with sed. Plus, you can easily save the buffer directly back to file, either the original or a new one.

(gnu sed also offers the -i option for saving back to the original file, but note that this is actually just using a tempfile behind the scenes to do so.)