Some command line tools and techniques for generating random strings.
openssl rand -base64 64
# cGuDXUoShzLaAgQSf7TX0trpQ6CtWD5u0VpGyBvGeuoYwFGDs+ZRLIP+TIFGyOln
# 3LYbPyKlHxkLfhiUKgCUSQ==
openssl rand -hex 64
# 4664fd45ca6c87453cdb607b206ab809069848b6b52fc7cb8af44f6d4a3d8eb2e4fc66a018597aa5875b0e70424117c258ce6538f4a41ee190a9accbb67b63c3
cat /dev/urandom | tr -dc 'a-zA-Z0-9-_!@#$%^&*()_+{}|:<>?=' | fold -w 64 | grep -i '[!@#$%^&*()_+{}|:<>?=]' | head -n 1
# o^(ud*t2}r:i$uK|5kPq-az{bb(fW}:IV2fEl5vV6jD<%FHfT8g*YxL4elBh26=k
mkpasswd -l 64