How to transform string with character codes into quoted form

Question

I have a string like New\x20Folder. Special characters is represented by their codes. I'd like to transform the string into quoted form: "New Folder".

The only available tools are bash and bunch of standard utilities like sed.

The first form is produced by the udev environment variable ID_FS_LABEL_ENC. The needed form is consumed by the autofs config file. It expects quoted strings.

Answer 1

Assuming that backslashes themselves are also escaped in your strings (as \x5c, presumably), which udev seems to do, you should use Bash's printf builtin:

printf -v translated '"%b"' "$ID_FS_LABEL_ENC"

If we try that on your example string:

$ ID_FS_LABEL_ENC='New\x20Folder'
$ printf -v translated '"%b"' "$ID_FS_LABEL_ENC"
$ echo "Translated to: '$translated'"
Translated to: '"New Folder"'

we get the transformation you wanted.

printf -v assigns the result of a standard printf-style translation into a variable, and the %b format is a Bash extension performing backslash escape sequences. This is not susceptible to any funny business with names containing odd but legitimate characters and doesn't require rewriting the string.

Answer 2

Try this:

string=$'New\x20Folder'

or

string="New\x20Folder"
string="$(echo -e "$string")"