Which characters need to be escaped when using Bas

Question

Is there any comprehensive list of characters that need to be escaped in Bash? Can it be checked just with sed?

In particular, I was checking whether % needs to be escaped or not. I tried

echo "h%h" | sed 's/%/i/g'

and worked fine, without escaping %. Does it mean % does not need to be escaped? Was this a good way to check the necessity?

And more general: are they the same characters to escape in shell and bash?

Answer 1

I noticed that bash automatically escapes some characters when using auto-complete.

For example, if you have a directory named dir:A, bash will auto-complete to dir\:A

Using this, I runned some experiments using characters of the ASCII table and derived the following lists:

Characters that bash escapes on auto-complete: (includes space)

 !"$&'()*,:;<=>?@[\]^`{|}

Characters that bash does not escape:

#%+-.0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz~

(I excluded /, as it cannot be used in directory names)