How to sanitize a string in bash?

Question

I have a free form string which I need to sanitize in bash in order to produce safe-and-nice filenames.

Example:

STAGE_NAME="Some usafe name 2/2#"

Expected sanitized result"

"some-unsafe-name-2-2"

Logic:

• lowercase chars
• replace all unsupported or unsafe chars with dash (including spaces)
• remove duplicated dashes
• remove any dashes from prefix or suffix

Use of external tools like sed is allowed as long they are portable (not using options that are no available on BSD/OSX/...).

Answer 1

You can use this pure bash function for this sanitization:

sanitize() {
   local s="${1?need a string}" # receive input in first argument
   s="${s//[^[:alnum:]]/-}"     # replace all non-alnum characters to -
   s="${s//+(-)/-}"             # convert multiple - to single -
   s="${s/#-}"                  # remove - from start
   s="${s/%-}"                  # remove - from end
   echo "${s,,}"                # convert to lowercase
}

Then call it as:

sanitize "///Some usafe       name  2/2##"
some-usafe-name-2-2

sanitize "Some usafe name 2/2#"
some-usafe-name-2-2 

---

Just for an academic exercise here is an awk one-liner doing the same:

awk -F '[^[:alnum:]]+' -v OFS=- '{$0=tolower($0); $1=$1; gsub(/^-|-$/, "")} 1'