A path that starts with a tilde character (~) is interpreted specially by the shell, for tilde expansion into a system user's home directory. By itself, it refers to the current user's home directory:
$ echo ~ /home/bashuser $ echo ~/important /home/bashuser/important
In this circumstance, it checks the value of the HOME environment variable first if it can. However, if this variable is blank or if the tilde is followed by any valid system username, Bash will attempt to find the home directory for that user with reference to the system password file, usually /etc/passwd:
$ echo ~root /root $ echo ~root/.ssh /root/.ssh
If the user does not exist, Bash will leave the tilde string the same, without raising an error:
$ echo ~notauser ...
