How can I escape forward slashes in a user input variable in bash?

Question

I'm working on a script to make setting up a Statamic site more efficient. The problem I'm running into is that the variable I'm using to replace a string in a file has unescaped forward slashes and is user input. How can I make sure that _site_url: http://statamic.com will become _site_url: http://example.com?

The code below will work as long as there are no forward slashes present.

echo "What's your site URL? Don't forget the protocol (ex. http://)!"
read -e SITE_URL

echo "%s/_site_url: http:\/\/statamic.com/_site_url: $SITE_URL/g
w
q
" | ex _config/settings.yaml

score 9 · Answer 1 · answered Aug 27 '14 at 22:44

Since you specifically mentioned bash instead of Bourne shell or generic Unix shell, I'd recommend using Bash's built in search/replace feature:

echo "What's your site URL? Don't forget the protocol (ex. http://)!"
read -e SITE_URL

echo Escaped URL: ${SITE_URL//\//\\\/}

Gilles Quénot · Accepted Answer · 2012-10-19T01:53:53.750

3

The problem is the delimiter in your ex command. We can put anything we'd like instead, I use @ here :

Try doing this :

 sed -i "s@_site_url: http://statamic.com/_site_url: $SITE_URL@g" _config/settings.yaml

Or with your ex command :

echo "What's your site URL? Don't forget the protocol (ex. http://)!"
read -e SITE_URL

echo "%s@_site_url: http://statamic.com@_site_url: $SITE_URL@g
w
q
" | ex _config/settings.yaml

edited Oct 19 '12 at 01:53

answered Oct 19 '12 at 00:48

Gilles Quénot

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Added `ex` command solution too. Tested ok on my `archlinux` box. – Gilles Quénot Oct 19 '12 at 00:54
Why do you use `ex` and not `sed` or `perl` ? – Gilles Quénot Oct 19 '12 at 01:35
sed creates a new file, so I'd have to delete it as well. perl didn't work when I tried another it for another problem in the script. ex doesn't create a new file. – Curtis Blackwell Oct 19 '12 at 01:41
Both `perl` & `sed` have `-i` switch, do you know that ? It creates a newfile yes, but in the background, exactly like `ex`. Try `strace -f -s 1000 -e trace=file bash script.ex` to figure it out. – Gilles Quénot Oct 19 '12 at 01:51
From what I read about the `-i` switch, it's an extension for both, so I don't want to rely on that. This script will be shared with others. – Curtis Blackwell Oct 19 '12 at 01:58

How can I escape forward slashes in a user input variable in bash?

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