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| Next: <a rel="next" accesskey="n" href="Scanning-All-Groups.html#Scanning-All-Groups">Scanning All Groups</a>, |
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| <h4 class="subsection">29.14.2 Looking Up One Group</h4> |
| |
| <p><a name="index-converting-group-name-to-group-ID-3411"></a><a name="index-converting-group-ID-to-group-name-3412"></a> |
| You can search the group database for information about a specific |
| group using <code>getgrgid</code> or <code>getgrnam</code>. These functions are |
| declared in <samp><span class="file">grp.h</span></samp>. |
| |
| <!-- grp.h --> |
| <!-- POSIX.1 --> |
| <div class="defun"> |
| — Function: struct group * <b>getgrgid</b> (<var>gid_t gid</var>)<var><a name="index-getgrgid-3413"></a></var><br> |
| <blockquote><p>This function returns a pointer to a statically-allocated structure |
| containing information about the group whose group ID is <var>gid</var>. |
| This structure may be overwritten by subsequent calls to |
| <code>getgrgid</code>. |
| |
| <p>A null pointer indicates there is no group with ID <var>gid</var>. |
| </p></blockquote></div> |
| |
| <!-- grp.h --> |
| <!-- POSIX.1c --> |
| <div class="defun"> |
| — Function: int <b>getgrgid_r</b> (<var>gid_t gid, struct group *result_buf, char *buffer, size_t buflen, struct group **result</var>)<var><a name="index-getgrgid_005fr-3414"></a></var><br> |
| <blockquote><p>This function is similar to <code>getgrgid</code> in that it returns |
| information about the group whose group ID is <var>gid</var>. However, it |
| fills the user supplied structure pointed to by <var>result_buf</var> with |
| the information instead of using a static buffer. The first |
| <var>buflen</var> bytes of the additional buffer pointed to by <var>buffer</var> |
| are used to contain additional information, normally strings which are |
| pointed to by the elements of the result structure. |
| |
| <p>If a group with ID <var>gid</var> is found, the pointer returned in |
| <var>result</var> points to the record which contains the wanted data (i.e., |
| <var>result</var> contains the value <var>result_buf</var>). If no group is found |
| or if an error occurred, the pointer returned in <var>result</var> is a null |
| pointer. The function returns zero or an error code. If the buffer |
| <var>buffer</var> is too small to contain all the needed information, the |
| error code <code>ERANGE</code> is returned and <var>errno</var> is set to |
| <code>ERANGE</code>. |
| </p></blockquote></div> |
| |
| <!-- grp.h --> |
| <!-- SVID, BSD --> |
| <div class="defun"> |
| — Function: struct group * <b>getgrnam</b> (<var>const char *name</var>)<var><a name="index-getgrnam-3415"></a></var><br> |
| <blockquote><p>This function returns a pointer to a statically-allocated structure |
| containing information about the group whose group name is <var>name</var>. |
| This structure may be overwritten by subsequent calls to |
| <code>getgrnam</code>. |
| |
| <p>A null pointer indicates there is no group named <var>name</var>. |
| </p></blockquote></div> |
| |
| <!-- grp.h --> |
| <!-- POSIX.1c --> |
| <div class="defun"> |
| — Function: int <b>getgrnam_r</b> (<var>const char *name, struct group *result_buf, char *buffer, size_t buflen, struct group **result</var>)<var><a name="index-getgrnam_005fr-3416"></a></var><br> |
| <blockquote><p>This function is similar to <code>getgrnam</code> in that is returns |
| information about the group whose group name is <var>name</var>. Like |
| <code>getgrgid_r</code>, it uses the user supplied buffers in |
| <var>result_buf</var> and <var>buffer</var>, not a static buffer. |
| |
| <p>The return values are the same as for <code>getgrgid_r</code> |
| <code>ERANGE</code>. |
| </p></blockquote></div> |
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