Format like this (note that in many cases the secret has been hex encoded)
<code>
otpauth://totp/<name>?secret=<base32_encoded_secret>&digits=6
</code>

This is a couple of ways to hex decode and base32 encode a secret that is in this case separated by $IFS (space or newline)
<code>
for hex in $( cat <file_with_hexsecret> ); do printf "\x$hex"; done | base32
for hex in 00 11 22 33 44 55 66 77 88 99 aa bb cc dd ee ff 00 11 22 33; do printf "\x$hex"; done | base32
</code>

To generate a secret
<code>
dd if=/dev/urandom bs=20 count=1 | xxd -ps
</code>