shell-file-name-chars

shell-file-name-chars is a variable defined in `shell.el'.
Its value is

"[]~/A-Za-z0-9+@:_.$#%,={}-"

Documentation:
String of characters valid in a file name.
This variable is used to initialize `comint-file-name-chars' in the
shell buffer. The value may depend on the operating system or shell.

You can customize this variable.