| 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 ?/span>, 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 ~?/span> command puts you in the previous directory, but the Korn shell provides an even shorter shortcut: cd ?/span> 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 Table 2.7. Tilde Substitution| ~ | replaced with $HOME | | ~user | replaced with the home directory of user | | ~?/span> | replaced with $OLDPWD (previous directory) | | ~+ | replaced with $PWD (current directory) |
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