How to print Hello!World

Question

More broadly, how to echo ! in bash without space in between

karthik@cosmic:~$ echo "Hello!World"
bash: !World: event not found
karthik@cosmic:~$ echo "Hello\!World"
Hello\!World
karthik@cosmic:~$ 

Answer 1

Thanks to someone, the solution is simple.

Remove those double quotes and escape the !:

echo Hello\!World

or with bash 4.3 or newer, use double quotes but make sure the ! is immediately followed by the closing quote:

echo "Hello!""World"

From the release notes in bash 4.3:

l. The history expansion character (!) does not cause history expansion when followed by the closing quote in a double-quoted string.

Best is to use single quotes inside which all characters lose their special meaning¹.

echo 'Hello!World'

Or disable csh-style history expansion altogether with:

histchars=

Or:

set +o histexpand

Or:

set +H

Note that history expansion is only enabled by default when bash is interactive, not in scripts.

---

^{As long as the deprecated `...` form of command substitution is not also used, as inside it, \ retains a special meaning even inside single quotes.}