138 lines
6.3 KiB
HTML
138 lines
6.3 KiB
HTML
|
<?xml version="1.0" encoding="UTF-8"?>
|
||
|
|
<!DOCTYPE html
|
||
|
|
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||
|
|
<html lang="en-us" xml:lang="en-us">
|
||
|
|
<head>
|
||
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
||
|
|
<meta name="security" content="public" />
|
||
|
|
<meta name="Robots" content="index,follow" />
|
||
|
|
<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
|
||
|
|
<meta name="DC.Type" content="reference" />
|
||
|
|
<meta name="DC.Title" content="Example: Using environment variables" />
|
||
|
|
<meta name="abstract" content="This program displays the value of an environment variable and then sets the environment variable to a new value." />
|
||
|
|
<meta name="description" content="This program displays the value of an environment variable and then sets the environment variable to a new value." />
|
||
|
|
<meta name="DC.Relation" scheme="URI" content="apiexmp.htm" />
|
||
|
|
<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
|
||
|
|
<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 1998, 2006" />
|
||
|
|
<meta name="DC.Format" content="XHTML" />
|
||
|
|
<meta name="DC.Identifier" content="apiexusvar" />
|
||
|
|
<meta name="DC.Language" content="en-us" />
|
||
|
|
<!-- All rights reserved. Licensed Materials Property of IBM -->
|
||
|
|
<!-- US Government Users Restricted Rights -->
|
||
|
|
<!-- Use, duplication or disclosure restricted by -->
|
||
|
|
<!-- GSA ADP Schedule Contract with IBM Corp. -->
|
||
|
|
<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
|
||
|
|
<link rel="stylesheet" type="text/css" href="./ic.css" />
|
||
|
|
<title>Example: Using environment variables</title>
|
||
|
|
</head>
|
||
|
|
<body id="apiexusvar"><a name="apiexusvar"><!-- --></a>
|
||
|
|
<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
|
||
|
|
<h1 class="topictitle1">Example: Using environment variables</h1>
|
||
|
|
<div><p>This program displays the value of an environment variable and
|
||
|
|
then sets the environment variable to a new value.</p>
|
||
|
|
<div class="section"><p>Use the Create C Module (CRTCMOD) and the Create Program (CRTPGM)
|
||
|
|
commands to create this program.</p>
|
||
|
|
<p>Call this program with one parameter
|
||
|
|
to display the environment variable specified by that parameter. Call this
|
||
|
|
program with two parameters to set the environment variable specified by the
|
||
|
|
first parameter to the value specified by the second parameter.</p>
|
||
|
|
<div class="note"><span class="notetitle">Note:</span> Read
|
||
|
|
the <a href="codedisclaimer.htm">Code license and disclaimer information</a> for important legal information.</div>
|
||
|
|
<pre>/******************************************************************/
|
||
|
|
/******************************************************************/
|
||
|
|
/* */
|
||
|
|
/* FUNCTION: Display the value of an environment variable and */
|
||
|
|
/* then set the environment variable to a new value. */
|
||
|
|
/* */
|
||
|
|
/* LANGUAGE: ILE C */
|
||
|
|
/* */
|
||
|
|
/* APIs USED: getenv(), putenv() */
|
||
|
|
/* */
|
||
|
|
/******************************************************************/
|
||
|
|
/******************************************************************/
|
||
|
|
|
||
|
|
#include <stdio.h>
|
||
|
|
#include <stdlib.h>
|
||
|
|
#include <errno.h>
|
||
|
|
#include <string.h>
|
||
|
|
|
||
|
|
#define BUFLEN 1024
|
||
|
|
|
||
|
|
int main(int argc, char *argv[])
|
||
|
|
{
|
||
|
|
int num=0; /* counter */
|
||
|
|
int rc; /* API return code */
|
||
|
|
int l1, l2; /* lengths of the two parameters */
|
||
|
|
char *envvar=NULL; /* pointer to an environment variable*/
|
||
|
|
char **envvaridx=NULL; /* pointer to an envvar pointer */
|
||
|
|
char envstring[BUFLEN];
|
||
|
|
/* buffer to construct putenv request*/
|
||
|
|
|
||
|
|
/* Show a small usage message. */
|
||
|
|
if ((argc != 2) && (argc != 3)) {
|
||
|
|
printf("Usage: %s <ENV_VAR> <new_value>\n OR \n"
|
||
|
|
"Usage: %s <ENV_VAR>\n", argv[0], argv[0]);
|
||
|
|
printf("Sets an environment variable to a user requested\n"
|
||
|
|
"value\n"
|
||
|
|
"OR\nDisplays the value of a single environment variable\n");
|
||
|
|
exit(1);
|
||
|
|
}
|
||
|
|
|
||
|
|
if (argc == 2) {
|
||
|
|
/* Called just to display the environment variables. */
|
||
|
|
envvar = getenv(argv[1]);
|
||
|
|
if (envvar == NULL) {
|
||
|
|
printf("No environment variable %s set\n",
|
||
|
|
argv[1]);
|
||
|
|
}
|
||
|
|
else {
|
||
|
|
printf("Environment variable: %s\n", envvar);
|
||
|
|
}
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* ELSE, called to set an environment variable. */
|
||
|
|
|
||
|
|
/* Check the size of the parameters and construct a string of */
|
||
|
|
/* the form "VAR=string" which is valid input to putenv. */
|
||
|
|
l1 = strlen(argv[1]);
|
||
|
|
l2 = strlen(argv[2]);
|
||
|
|
if (l1+l2+2 >= BUFLEN) {
|
||
|
|
printf("Only 1024 characters total allowed for this test\n");
|
||
|
|
exit(1);
|
||
|
|
}
|
||
|
|
memcpy(envstring, argv[1], l1);
|
||
|
|
envstring[l1] = '=';
|
||
|
|
memcpy(&envstring[l1+1], argv[2], l2);
|
||
|
|
envstring[l1+l2+1]='\0';
|
||
|
|
|
||
|
|
/* Now that the string is built, let's see if the environment */
|
||
|
|
/* variable was already set. */
|
||
|
|
envvar = getenv(argv[1]);
|
||
|
|
if (envvar == NULL) {
|
||
|
|
printf("Setting NEW environment variable %s\n",
|
||
|
|
envstring);
|
||
|
|
}
|
||
|
|
else {
|
||
|
|
printf("Resetting OLD environment variable from: %s\n to %s\n",
|
||
|
|
envvar, envstring);
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Now actually set the environment variable. */
|
||
|
|
rc = putenv(envstring);
|
||
|
|
if (rc < 0) {
|
||
|
|
printf("putenv failed, errno = %d\n", errno);
|
||
|
|
return -1;
|
||
|
|
}
|
||
|
|
printf("Environment variable set\n");
|
||
|
|
return 0;
|
||
|
|
}</pre>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
<div>
|
||
|
|
<div class="familylinks">
|
||
|
|
<div class="parentlink"><strong>Parent topic:</strong> <a href="apiexmp.htm" title="Contains example programs that use APIs and exit programs.">Examples: APIs</a></div>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
</body>
|
||
|
|
</html>
|