パスワードの最小長さを変更する方法

/etc/pam.d/common-password の次の行を書き換える。

# here are the per-package modules (the "Primary" block)
password        [success=1 default=ignore]      pam_unix.so obscure sha512

↓

# here are the per-package modules (the "Primary" block)
password        [success=1 default=ignore]      pam_unix.so minlen=0 sha512