Finding out what characters a given font supports

Question

How do I extract the list of supported Unicode characters from a TrueType or embedded OpenType font on Linux?

Is there a tool or a library I can use to process a .tt

Answer 1

Here is a POSIX[1] shell script that can print the code point and the character in a nice and easy way with the help of fc-match which is mentioned in Neil Mayhew's answer (it can even handle up to 8-hex-digit Unicode):

#!/bin/sh
for range in $(fc-match --format='%{charset}\n' "$1"); do
    for n in $(seq "0x${range%-*}" "0x${range#*-}"); do
        n_hex=$(printf "%04x" "$n")
        # using \U for 5-hex-digits
        printf "%-5s\U$n_hex\t" "$n_hex"
        count=$((count + 1))
        if [ $((count % 10)) = 0 ]; then
            printf "\n"
        fi
    done
done
printf "\n"

You can pass the font name or anything that fc-match accepts:

$ ls-chars "DejaVu Sans"

Updated content:

I learned that subshell is very time consuming (the printf subshell in my script). So I managed to write a improved version that is 5-10 times faster!

#!/bin/sh
for range in $(fc-match --format='%{charset}\n' "$1"); do
    for n in $(seq "0x${range%-*}" "0x${range#*-}"); do
        printf "%04x\n" "$n"
    done
done | while read -r n_hex; do
    count=$((count + 1))
    printf "%-5s\U$n_hex\t" "$n_hex"
    [ $((count % 10)) = 0 ] && printf "\n"
done
printf "\n"

Old version:

$ time ls-chars "DejaVu Sans" | wc
    592   11269   52740

real    0m2.876s
user    0m2.203s
sys     0m0.888s

New version (the line number indicates 5910+ characters, in 0.4 seconds!):

$ time ls-chars "DejaVu Sans" | wc
    592   11269   52740

real    0m0.399s
user    0m0.446s
sys     0m0.120s

End of update

Sample output (it aligns better in my st terminal