Question

I am trying to do a find and replace with sed and BASH variables. As the replaced content contains many / characters, I have used # instead of /, as is typically used in sed:

 sed -i "0,\#^$word#s##$replacement#" ./file

The item I want to replace contains the \ symbol:

 replacement=$(echo "\macro{30\percent of bears eat fish.}")

However, when I do the replacement, \ always disappears.

• I do not have control over the content within "\macro{30\percent of bears eat fish.}"
• If \t appears, it is interpreted as an indent, but I just want it to print as \t in the output.

How can I do a find and replace with sed when \, /, or other symbols might be found within the replacement text?

Answer 1

word=$(echo -E "wo\rd")
replacement=$(echo -E "r/e\p")

echo -ne "a\nb\nc\nd\nwo\\\\rd\ne\nf\n" | sed -e "0,\#^${word//\\/\\\\}# s##${replacement//\\/\\\\}#"

Note that you will still have problems with other characters, & and # in replacement string and of course all valid regex characters in the word string

The below takes care of the regular expression chars

word=$(echo -E "^\$.*[#]wo\rd" | sed 's:[]\[\^\$\.\*#\\]:\\&:g')
replacement=$(echo -E "&#r/e\p" | sed 's:[&#\\]:\\&:g')

echo -ne "a\nb\nc\nd\n^\$.*[#]wo\\\\rd\ne\nf\n" | sed -e "0,\#^${word}# s##${replacement}#"