sed rare-delimiter (other than & | / ?...)

Question

I am using the Unix sed command on a string that can contain all types of characters (&, |, !, /, ?, etc).

Is there a complex delimiter (with two characters?) that can fix the error:

sed: -e expression #1, char 22: unknown option to `s'

Answer 1

The characters in the input file are of no concern - sed parses them fine. There may be an issue, however, if you have most of the common characters in your pattern - or if your pattern may not be known beforehand.

At least on GNU sed, you can use a non-printable character that is highly improbable to exist in your pattern as a delimiter. For example, if your shell is Bash:

$ echo '|||' | sed s$'\001''|'$'\001''/'$'\001''g'

In this example, Bash replaces $'\001' with the character that has the octal value 001 - in ASCII it's the SOH character (start of heading).

Since such characters are control/non-printable characters, it's doubtful that they will exist in the pattern. Unless, that is, you are doing something weird like modifying binary files - or Unicode files without the proper locale settings.