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system library. In list context, the return values from the

various get routines are as follows:

<pre class="verbatim"> ($name,$passwd,$uid,$gid,

$quota,$comment,$gcos,$dir,$shell,$expire) = getpw*

($name,$passwd,$gid,$members) = getgr*

($name,$aliases,$addrtype,$length,@addrs) = gethost*

($name,$aliases,$proto) = getproto*

($name,$aliases,$port,$proto) = getserv*</pre>

($name,$aliases,$addrtype,$net) = getnet*

($name,$aliases,$proto) = getproto*

(If the entry doesn't exist you get a null list.)

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The exact meaning of the $gcos field varies but it usually contains

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the real name of the user (as opposed to the login name) and other

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in your system, please consult your getpwnam(3) documentation and your

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pwd.h file. You can also find out from within Perl what your

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$quota and $comment fields mean and whether you have the $expire field

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by using the <code class="inline"><a class="l_w" href="../Config.html">Config</a></code> module and the values <code class="inline">d_pwquota</code>

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, <code class="inline">d_pwage</code>

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by using the <code class="inline">Config</code>

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module and the values <code class="inline">d_pwquota</code>

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, <code class="inline">d_pwage</code>

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<code class="inline">d_pwchange</code>

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, <code class="inline">d_pwcomment</code>

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, and <code class="inline">d_pwexpire</code>

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<code class="inline">d_pwchange</code>

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, <code class="inline">d_pwcomment</code>

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, and <code class="inline">d_pwexpire</code>

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. Shadow password

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files are only supported if your vendor has implemented them in the

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intuitive fashion that calling the regular C library routines gets the

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facility are unlikely to be supported.

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The $members value returned by getgr*() is a space separated list of

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the login names of the members of the group.

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For the gethost*() functions, if the <code class="inline">h_errno</code>

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For the gethost*() functions, if the <code class="inline">h_errno</code>

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variable is supported in

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C, it will be returned to you via <code class="inline">$?</code>

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if the function call fails. The

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addresses returned by the corresponding system library call. In the

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Internet domain, each address is four bytes long and you can unpack it

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by saying something like:

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<pre class="verbatim"> ($a,$b,$c,$d) = <a class="l_k" href="../functions/unpack.html">unpack</a>('C4',$addr[0]);</pre>

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<pre class="verbatim"> ($a,$b,$c,$d) = <a class="l_k" href="../functions/unpack.html">unpack</a>('W4',$addr[0]);</pre>

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The Socket library makes this slightly easier:

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<pre class="verbatim"> <a class="l_k" href="../functions/use.html">use</a> <a class="l_w" href="../Socket.html">Socket</a>;

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<pre class="verbatim"> <a class="l_k" href="../functions/use.html">use</a> Socket;

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$iaddr = inet_aton("127.1"); # or whatever address

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$name = <a class="l_k" href="../functions/gethostbyaddr.html">gethostbyaddr</a>($iaddr, AF_INET);</pre>

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$name = <a class="l_k" href="../functions/gethostbyaddr.html">gethostbyaddr</a>($iaddr, AF_INET);</pre>

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<pre class="verbatim"> # or going the other way

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$straddr = inet_ntoa($iaddr);</pre>

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In the opposite way, to resolve a hostname to the IP address

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you can write this:

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<pre class="verbatim"> <a class="l_k" href="../functions/use.html">use</a> Socket;

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$packed_ip = <a class="l_k" href="../functions/gethostbyname.html">gethostbyname</a>("www.perl.org");

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if (<a class="l_k" href="../functions/defined.html">defined</a> $packed_ip) {

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$ip_address = inet_ntoa($packed_ip);

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}</pre>

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Make sure <gethostbyname()> is called in SCALAR context and that

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its return value is checked for definedness.

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If you get tired of remembering which element of the return list

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contains which return value, by-name interfaces are provided

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in standard modules: <code class="inline"><a class="l_w" href="../File/stat.html">File::stat</a></code>, <code class="inline"><a class="l_w" href="../Net/hostent.html">Net::hostent</a></code>, <code class="inline"><a class="l_w" href="../Net/netent.html">Net::netent</a></code>,

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<code class="inline"><a class="l_w" href="../Net/protoent.html">Net::protoent</a></code>, <code class="inline"><a class="l_w" href="../Net/servent.html">Net::servent</a></code>, <code class="inline"><a class="l_w" href="../Time/gmtime.html">Time::gmtime</a></code>, <code class="inline"><a class="l_w" href="../Time/localtime.html">Time::localtime</a></code>,

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and <code class="inline"><a class="l_w" href="../User/grent.html">User::grent</a></code>. These override the normal built-ins, supplying

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in standard modules: <code class="inline">File::stat</code>

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, <code class="inline">Net::hostent</code>

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, <code class="inline">Net::netent</code>

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<code class="inline">Net::protoent</code>

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, <code class="inline">Net::servent</code>

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, <code class="inline">Time::gmtime</code>

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, <code class="inline">Time::localtime</code>

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and <code class="inline">User::grent</code>

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. These override the normal built-ins, supplying

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versions that return objects with the appropriate names

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for each field. For example:

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<pre class="verbatim"> <a class="l_k" href="../functions/use.html">use</a> <a class="l_w" href="../File/stat.html">File::stat</a>;

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<a class="l_k" href="../functions/use.html">use</a> <a class="l_w" href="../User/pwent.html">User::pwent</a>;

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<pre class="verbatim"> <a class="l_k" href="../functions/use.html">use</a> File::stat;

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<a class="l_k" href="../functions/use.html">use</a> User::pwent;

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$is_his = (<a class="l_k" href="../functions/stat.html">stat</a>($filename)->uid == pwent($whoever)->uid);</pre>

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Even though it looks like they're the same method calls (uid),

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they aren't, because a <code class="inline"><a class="l_w" href="../File/stat.html">File::stat</a></code> object is different from

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a <code class="inline"><a class="l_w" href="../User/pwent.html">User::pwent</a></code> object.

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they aren't, because a <code class="inline">File::stat</code>

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object is different from

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a <code class="inline">User::pwent</code>

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object.

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</li>

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</ul>

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</div>

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</form>

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<h2>Labels:</h2>

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