URL Encode a String with POSIX Shell

url_encode.sh

#!/bin/sh

# https://en.wikipedia.org/wiki/Percent-encoding

# https://stackoverflow.com/questions/38015239/url-encoding-a-string-in-shell-script-in-a-portable-way

# https://www.gnu.org/software/gettext/manual/html_node/The-LANGUAGE-variable.html#The-LANGUAGE-variable
# "The variable LANGUAGE is ignored if the locale is set to ‘C’"
# Not entirely sure why this is done to be honest
LANG=C;

while IFS= read -r c;
do
    case "$c" in 
        # Continue on non-reserved characters
        [a-zA-Z0-9.~_-])
            printf "$c"
            continue 
        ;; 
    esac

    # Don't do 'printf "$c"' since it breaks on '%' as input
    printf '%s' "$c" | od -An -tx1 | tr ' ' % | tr -d '\n'
done <<EOF
$(fold -w1)
EOF
# ^ This reads one character at a time by setting the column width to 1.
# Meaning THIS will be wrapped to:
# T
# H 
# I
# S
# This is really clever but also really hacky