Section 7.8. Tilde Substitution

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7.8. Tilde Substitution

Any token of the form ~name is subject to tilde substitution. The shell checks the password file to see if name is a valid user name, and if it is, replaces the ~name sequence with the full pathname of the user's home directory. If it isn't, the ~name sequence is left unchanged. Tilde substitution occurs after aliases are processed. Figure 7-16 is a table of the tilde substitutions, including the special cases ~+ and ~-.

Figure 7-16. Tilde substitutions in the Korn shell.

Tilde sequence	Replaced by
~	$HOME
~user	home directory of user
~/pathname	$HOME/pathname
~+	$PWD (current working directory)
~-	$OLDPWD (previous working directory)

The predefined local variables PWD and OLDPWD are described later in this chapter. Here are some examples of tilde substitution:

$ pwd /home/glass        ...current working directory. $ echo ~ /home/glass        ...my home directory. $ cd /             ...change to root directory. $ echo ~+ /                  ...current working directory. $ echo ~- /home/glass        ...previous working directory. $ echo ~dcox /home/dcox         ...another user's home directory. $ _