#### 10.4.5 Details of Tilde Expansion

It's a standard part of shell syntax that you can use ‘`~`’ at the beginning of a file name to stand for your own home directory. You can use ‘`~user`’ to stand for user's home directory.

Tilde expansion is the process of converting these abbreviations to the directory names that they stand for.

Tilde expansion applies to the ‘`~`’ plus all following characters up to whitespace or a slash. It takes place only at the beginning of a word, and only if none of the characters to be transformed is quoted in any way.

Plain ‘`~`’ uses the value of the environment variable `HOME` as the proper home directory name. ‘`~`’ followed by a user name uses `getpwname` to look up that user in the user database, and uses whatever directory is recorded there. Thus, ‘`~`’ followed by your own name can give different results from plain ‘`~`’, if the value of `HOME` is not really your home directory.