Linux Notes

Bash test command

Use [[ ... ]] instead of [ ... ] to test a condition in Bash. The latter is poor in function and unmentioned in the official GNU Bash document at all.

Disable password login for user

passwd -l {username}

while the SSH key login is still possible for the user.

To enable the password login again:

passwd -u {username}

Note: this enable a user to login without a password!

passwd -d {username}