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| <h4 class="subsection">10.4.5 Details of Tilde Expansion</h4> |
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| <p>It's a standard part of shell syntax that you can use ‘<samp><span class="samp">~</span></samp>’ at the |
| beginning of a file name to stand for your own home directory. You |
| can use ‘<samp><span class="samp">~</span><var>user</var></samp>’ to stand for <var>user</var>'s home directory. |
| |
| <p><dfn>Tilde expansion</dfn> is the process of converting these abbreviations |
| to the directory names that they stand for. |
| |
| <p>Tilde expansion applies to the ‘<samp><span class="samp">~</span></samp>’ 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. |
| |
| <p>Plain ‘<samp><span class="samp">~</span></samp>’ uses the value of the environment variable <code>HOME</code> |
| as the proper home directory name. ‘<samp><span class="samp">~</span></samp>’ followed by a user name |
| uses <code>getpwname</code> to look up that user in the user database, and |
| uses whatever directory is recorded there. Thus, ‘<samp><span class="samp">~</span></samp>’ followed |
| by your own name can give different results from plain ‘<samp><span class="samp">~</span></samp>’, if |
| the value of <code>HOME</code> is not really your home directory. |
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