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| <h4 class="subsection">29.12.3 Logging In and Out</h4> |
| |
| <p>These functions, derived from BSD, are available in the separate |
| <samp><span class="file">libutil</span></samp> library, and declared in <samp><span class="file">utmp.h</span></samp>. |
| <a name="index-utmp_002eh-3383"></a> |
| Note that the <code>ut_user</code> member of <code>struct utmp</code> is called |
| <code>ut_name</code> in BSD. Therefore, <code>ut_name</code> is defined as an alias |
| for <code>ut_user</code> in <samp><span class="file">utmp.h</span></samp>. |
| |
| <!-- utmp.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Function: int <b>login_tty</b> (<var>int filedes</var>)<var><a name="index-login_005ftty-3384"></a></var><br> |
| <blockquote><p>This function makes <var>filedes</var> the controlling terminal of the |
| current process, redirects standard input, standard output and |
| standard error output to this terminal, and closes <var>filedes</var>. |
| |
| <p>This function returns <code>0</code> on successful completion, and <code>-1</code> |
| on error. |
| </p></blockquote></div> |
| |
| <!-- utmp.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Function: void <b>login</b> (<var>const struct utmp *entry</var>)<var><a name="index-login-3385"></a></var><br> |
| <blockquote><p>The <code>login</code> functions inserts an entry into the user accounting |
| database. The <code>ut_line</code> member is set to the name of the terminal |
| on standard input. If standard input is not a terminal <code>login</code> |
| uses standard output or standard error output to determine the name of |
| the terminal. If <code>struct utmp</code> has a <code>ut_type</code> member, |
| <code>login</code> sets it to <code>USER_PROCESS</code>, and if there is an |
| <code>ut_pid</code> member, it will be set to the process ID of the current |
| process. The remaining entries are copied from <var>entry</var>. |
| |
| <p>A copy of the entry is written to the user accounting log file. |
| </p></blockquote></div> |
| |
| <!-- utmp.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Function: int <b>logout</b> (<var>const char *ut_line</var>)<var><a name="index-logout-3386"></a></var><br> |
| <blockquote><p>This function modifies the user accounting database to indicate that the |
| user on <var>ut_line</var> has logged out. |
| |
| <p>The <code>logout</code> function returns <code>1</code> if the entry was successfully |
| written to the database, or <code>0</code> on error. |
| </p></blockquote></div> |
| |
| <!-- utmp.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Function: void <b>logwtmp</b> (<var>const char *ut_line, const char *ut_name, const char *ut_host</var>)<var><a name="index-logwtmp-3387"></a></var><br> |
| <blockquote><p>The <code>logwtmp</code> function appends an entry to the user accounting log |
| file, for the current time and the information provided in the |
| <var>ut_line</var>, <var>ut_name</var> and <var>ut_host</var> arguments. |
| </p></blockquote></div> |
| |
| <p><strong>Portability Note:</strong> The BSD <code>struct utmp</code> only has the |
| <code>ut_line</code>, <code>ut_name</code>, <code>ut_host</code> and <code>ut_time</code> |
| members. Older systems do not even have the <code>ut_host</code> member. |
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