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| <h4 class="subsection">27.7.1 Identifying the Controlling Terminal</h4> |
| |
| <p><a name="index-controlling-terminal_002c-determining-3228"></a> |
| You can use the <code>ctermid</code> function to get a file name that you can |
| use to open the controlling terminal. In the GNU library, it returns |
| the same string all the time: <code>"/dev/tty"</code>. That is a special |
| “magic” file name that refers to the controlling terminal of the |
| current process (if it has one). To find the name of the specific |
| terminal device, use <code>ttyname</code>; see <a href="Is-It-a-Terminal.html#Is-It-a-Terminal">Is It a Terminal</a>. |
| |
| <p>The function <code>ctermid</code> is declared in the header file |
| <samp><span class="file">stdio.h</span></samp>. |
| <a name="index-stdio_002eh-3229"></a> |
| <!-- stdio.h --> |
| <!-- POSIX.1 --> |
| |
| <div class="defun"> |
| — Function: char * <b>ctermid</b> (<var>char *string</var>)<var><a name="index-ctermid-3230"></a></var><br> |
| <blockquote><p>The <code>ctermid</code> function returns a string containing the file name of |
| the controlling terminal for the current process. If <var>string</var> is |
| not a null pointer, it should be an array that can hold at least |
| <code>L_ctermid</code> characters; the string is returned in this array. |
| Otherwise, a pointer to a string in a static area is returned, which |
| might get overwritten on subsequent calls to this function. |
| |
| <p>An empty string is returned if the file name cannot be determined for |
| any reason. Even if a file name is returned, access to the file it |
| represents is not guaranteed. |
| </p></blockquote></div> |
| |
| <!-- stdio.h --> |
| <!-- POSIX.1 --> |
| <div class="defun"> |
| — Macro: int <b>L_ctermid</b><var><a name="index-L_005fctermid-3231"></a></var><br> |
| <blockquote><p>The value of this macro is an integer constant expression that |
| represents the size of a string large enough to hold the file name |
| returned by <code>ctermid</code>. |
| </p></blockquote></div> |
| |
| <p>See also the <code>isatty</code> and <code>ttyname</code> functions, in |
| <a href="Is-It-a-Terminal.html#Is-It-a-Terminal">Is It a Terminal</a>. |
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