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<!DOCTYPE concept

  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

<concept id="GUID-00FFF2B3-F8E4-5CBF-B031-240D98BB2111" xml:lang="en"><title>External

Programs</title><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>External programs are executables built outside but which can be launched

from the Zsh command prompt. </p>

<p>If the command is neither built-in, nor specified with an absolute pathname,

the shell will look in the <filepath>\sys\bin</filepath> on each drive in

reverse alphabetical order (<filepath>y:</filepath>, <filepath>x:</filepath>,...

to <filepath>b:</filepath>, <filepath>a:</filepath> and later <filepath>z:</filepath>)

and execute the first external program found. </p>

<p>To execute the external program directly give the following command at

the command-prompt: </p>

<p><userinput>command &lt;ext_pgm&gt;</userinput> </p>

<p>where <codeph>ext_pgm</codeph> is the name of the external program. </p>

<p>For example: </p>

<p>The program below reads input from Zsh and writes data to Zsh which can

then be redirected back to the Telnet client. </p>

<codeblock id="GUID-2A92BFF9-D69D-5C18-B657-9D7D5738EA22" xml:space="preserve">#include &lt;stdio.h&gt;

#include <string.h>

#include <unistd.h>

int  main()

    {

    char userData[20]; char ch; int x=0;

    memset(userData,0,20);

    x=read(0,userData, 20);    

    while(strcmp(userData, "quit"))

        {

        write(1, userData, x);

        memset(userData,0,20);

        x=read(0,userData, 20);        

        }        

    return 0;                 

    }

</codeblock>

<section id="GUID-A2C89E91-C5A5-49D9-A3A5-E9FB54A01BE1"><title>Limitations</title> <p>P.I.P.S. applications and native Symbian

applications can be launched from the Telnet client. However, to view the

output of the program or interact with it, the standard input and output of

the program must be accessible to the Telnet server. This is only possible

with P.I.P.S. applications. With native applications you will only be able

to retrieve the termination status; you will not be able to view the output

or interact with the program. </p> <p>Permission will be denied for external

programs that does not have the required capabilities to access directories

that contain <filepath>/sys</filepath> and <filepath>/private</filepath> in

their directory path. </p> <p> <b>Note:</b> For more information about the

external commands supported by Zsh, see the <xref href="GUID-3F577531-9798-537F-8F8B-7CAB0257560C.dita">Zsh

Command Syntax</xref> section. </p> </section>

<section id="GUID-164C2D77-8150-41FB-ABAB-FA1C52A59E21"><title>See also</title> <p>For information on porting Standard C

applications to the Symbian platform see the <xref href="GUID-E2DE2C6F-E071-5E88-96F1-D71DDED84609.dita">P.I.P.S.

Guide</xref>. </p> </section>