Tilde Substitution

Tilde substitution is used to substitute the pathname of a user's home directory for ∼user. Words in the command line that start with the tilde character cause the Korn shell to check the rest of the word up to a slash. If the tilde character is found alone or is only followed by a slash, it is replaced with the value of the HOME variable. This is a handy shortcut borrowed from the C shell. For example, to print the pathname of your home directory:

					$ echo ∼
					/home/anatole
				

or to list its contents:

					$ ls ∼/
					NEWS         bin         pc
					asp          mail        src
				

If the tilde character is followed by a login name file, it is replaced with the home directory of that user. Here we change directory to the tools directory in smith's home directory:

					$ cd ∼smith/tools
					$ pwd
					/home/users/admin/smith/tools
				

If the tilde character is followed by a + or –, it is replaced with the value of PWD (current directory) and OLDPWD (previous directory), respectively. This is not very useful for directory navigation, since cd ∼+ leaves you in the current directory. The cd ∼– command puts you in the previous directory, but the Korn shell provides an even shorter shortcut: cd – does the same thing, except that it also displays the current directory.

					$ pwd
					/home/users/admin/smith/tools
					$ cd /usr/bin
					$ cd ∼-
					$ pwd
					/home/users/admin/smith/tools
					$ cd -
					/usr/bin