[SOLVED] Replace only single instance of a character using sed

Issue

I need to replace only single instance of backslash.

Input: \\apple\\\orange\banana\\\\grape\\\\\
Output: \\apple\\\orangebanana\\\\grape\\\\\
Tried using sed 's/\\//g' which is replacing all backslashes

Note: The previous character to single backslash can be anything including alphanumeric or special characters. And it's a multiline text file.

Appreciate your help on this.

Solution

If you want to consider perl then lookahead and lookahead is exactly what you need here:

perl -pe 's~(?<!\\)\\(?!\\)~~g' file

\\apple\\\orangebanana\\\\grape\\\\\

Details

• (?<!\\): Negative lookbehind to make sure that previous char is not \
• \\: Match a \
• (?!\\): Negative lookahead to make sure that next char is not \

---

If you want to use sed only then I suggest:

sed -E -e ':a' -e 's~(^|[^\\])\\([^\\]|$)~\1\2~g; ta' g

Answered By - anubhava

Answer Checked By - Dawn Plyler (WPSolving Volunteer)