[reify]

good old dev urandom

cat /dev/random | tr -dc 'a-zA-Z0-9' | fold -w 14 | head -n 10

cat /dev/random | tr -dc '0-9' | fold -w 6 | head -n 10

cat /dev/random | tr -dc 'abcdef0-9' | fold -w 20 | head -n 10

using character classes:

cat /dev/urandom | tr -cd '[:graph:]' | fold -w 16 | head -n 10

cat /dev/urandom | tr -cd '[:print:]' | fold -w 12 | head -n 10

cat /dev/urandom | tr -cd '[:alnum:]' | fold -w 10 | head -n 10

cat /dev/urandom | tr -cd '[:xdigit:]' | fold -w 15 | head -n 10