sed search and replace strings containing /
bash, sed
Solution
Don't escape the backslashes; you'll confuse yourself. Use a different symbol after the `s` command that doesn't appear in the text (I'm using `%` in the example below):
line_old='myparam /path/to/a argB=/path/to/B xo'
line_new='myparam /path/to/c argB=/path/to/D xo'
sed -i "s%$line_old%$line_new%g" /etc/myconfig
Also, enclose the whole string in double quotes; using single quotes means that `sed` sees `$line` (in the original) instead of the expanded value. Inside single quotes, there is no expansion and there are no metacharacters. If your text can contain almost any plain text character, use a control character (e.g. control-A or control-G) as the delimiter.
Note that the use of `-i` here mirrors what is in the question, but that assumes the use of GNU `sed`. BSD `sed` (found on Mac OS X too) requires a suffix. You can use `sed -i '' …` to replace in situ; that does not work with GNU `sed`. To be portable between the two, use `-i.bak`; that will work with both — but gives you a backup file that you'll probably want to delete. Other Unix platforms (e.g. AIX, HP-UX, Solaris) may have variants of `sed` that do not support `-i` at all. It is not required by the POSIX specification for `sed`.
Problem
I am having trouble figuring out how to use `sed` to search and replace strings containing the `/` character in a text file `/etc/myconfig`. For instance, in my existing text file, I have: ``` myparam /path/to/a argB=/path/to/B xo ``` and I want this replaced by: ``` myparam /path/to/c argB=/path/to/D xo ``` I attempted doing this in bash: ``` line='myparam /path/to/a argB=/path/to/B xo' line_new='myparam /path/to/c argB=/path/to/D xo' sed -i 's/$line/$line_new/g' /etc/myconfig ``` But nothing happens. Attempting ``` grep -rn "$line" /etc/myconfig ``` does return me `'myparam /path/to/a argB=/path/to/B xo'` though. What's the correct way to express my `sed` command to execute this search and replace and correctly deal with the `/` command? (I reckon that the `/` character in my strings are the ones giving me the problem because I used a similar `sed` command to search and replace another line in the text file with no problems and that line does not have a `/` character.