unix - Interpret as fixed string/literal and not regex using sed

Question

For grep there's a fixed string option, -F (fgrep) to turn off regex interpretation of the search string. Is there a similar facility for sed? I couldn't find anything in the man. A recommendation of another gnu/linux tool would also be fine.

I'm using sed for the find and replace functionality: sed -i "s/abc/def/g"

Answer 1

Do you have to use sed? If you're writing a bash script, you can do

#!/bin/bash

pattern='abc'
replace='def'
file=/path/to/file
tmpfile="${TMPDIR:-/tmp}/$( basename "$file" ).$$"

while read -r line
do
  echo "${line//$pattern/$replace}"
done < "$file" > "$tmpfile" && mv "$tmpfile" "$file"

With an older Bourne shell (such as ksh88 or POSIX sh), you may not have that cool ${var/pattern/replace} structure, but you do have ${var#pattern} and ${var%pattern}, which can be used to split the string up and then reassemble it. If you need to do that, you're in for a lot more code - but it's really not too bad.

If you're not in a shell script already, you could pretty easily make the pattern, replace, and filename parameters and just call this. :)

PS: The ${TMPDIR:-/tmp} structure uses $TMPDIR if that's set in your environment, or uses /tmp if the variable isn't set. I like to stick the PID of the current process on the end of the filename in the hopes that it'll be slightly more unique. You should probably use mktemp or similar in the "real world", but this is ok for a quick example, and the mktemp binary isn't always available.