sed single qoutes, double qoutes, delimeters

Question

I am confused a little bit. I would like to swap 2 directory in the apache2 config files with the sed program.

APACHE_CONF=/etc/apache2/apache2.conf
FULL_DIR=/home/$USER/new
DEFAULT_DIR=/var/www/html`

This works fine:

sudo sed -i.bak 's|'$DEFAULT_DIR'|'$FULL_DIR'|' "$APACHE_CONF"

These are not (these don't have error, just do nothing):

sudo sed -i.bak 's/"$DEFAULT_DIR"/"$FULL_DIR"/' "$APACHE_CONF"
sudo sed -i.bak 's/\"$DEFAULT_DIR"/\"$FULL_DIR"/' "$APACHE_CONF"

Can anybody explain why don't these work and why does the first one work?

Quoting prevents the *shell* from treating characters as special - it does not help in preventing `sed` itself from treating `/` as special — steeldriver, May 11 '15 at 15:33
That is right. I used backslash after forward slash to sign to the interpreter forward slash is the delimiter. You need to use this: | as a delimiter. [According this.](http://www.linuxtopia.org/online_books/linux_tool_guides/the_sed_faq/sedfaq4_023.html) — ampika, May 11 '15 at 15:46
You can use `/` as the `sed` delimiter only if you escape every `/` in the pattern and replacement e.g. define `DEFAULT_DIR=\/var\/www\/html` and so on. Putting a backslash **after** the `/` like `s/\"$DEFAULT_DIR"/` is not the same thing (in fact it just makes `sed` treat the first `"` as literal, so that it no longer matches the text in your file). — steeldriver, May 11 '15 at 16:11

0 Answers0