| After alias substitution is performed, each word is checked to see if it begins with an unquoted ~. For tilde substitution, word also refers to the word portion of parameter expansion (see Parameter Expansion below). If it does, then the word up to a / is checked to see if it matches a user name in the password database (often the /etc/passwd file). If a match is found, the ~ and the matched login name are replaced by the login directory of the matched user. If no match is found, the original text is left unchanged. A ~ by itself, or in front of a /, is replaced by $HOME. A ~ followed by a + or - is replaced by the value of $PWD and $OLDPWD respectively. In addition, when expanding a variable assignment, tilde substitution is attempted when the value of the assignment begins with a ~, and when a ~ appears after a :. The : also terminates a ~ login name. |