How to use ! in the sed command?

Question

Apologize if you feel this question very basic. Anyways, I am typing
sed '/[iI]t/ a\\ Found it!' data but it says the error event not found.

I tried escaping that ! with backslash \! but it doesn't work.

I don't understand when backslash \ can escape a character and use it literally then why doesn't it work in sed?

@StephenHarris C Shell. I know Bash is better, but can't I work on Csh? — Anonymous, Jul 20 '16 at 22:02
What's the a// bit for? echo blah | sed 'a\\<NL>!' appends a ! without issue in csh... (where <NL> is a literal newline). — thrig, Jul 20 '16 at 23:01
Possible duplicate of How to use a special character as a normal one? — Stéphane Chazelas, Jul 21 '16 at 16:28

score 4 · Accepted Answer · answered Feb 06 '17 at 22:09

Which OS did you try it on? On HP-UX 8.11 csh there are 2 ways to cancel the speacial meaning of exclamation mark for history substitutions (see History substitutions in man csh).

Put space after ! (couple of other characters work too)
```
sed '/[iI]t/ a\\
Found it! ' data
```

Escape it via \!

sed '/[iI]t/ a\\
Found it\!' data

This actually also works with double quotes:

sed "/[iI]t/ a\\
Found it\!" data

How to use ! in the sed command?

1 Answers1