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Synopsis:
#include <env.h>
int setenv( const char *name,
const char *newvalue,
int overwrite );
int _setenv( const char *name,
const char *newvalue,
int overwrite );
int _wsetenv( const wchar_t *name,
const wchar_t *newvalue,
int overwrite );
Description:
The environment list consists of a number of environment names, each of
which has a value associated with it. Entries can be added to the
environment list with the DOS set command or with the setenv function.
All entries in the environment list can be displayed by using the DOS
set command with no arguments. A program can obtain the value for an
environment variable by using the getenv function.
The setenv function searches the environment list for an entry of the
form name=value. If no such string is present, setenv adds an entry of
the form name=newvalue to the environment list. Otherwise, if the
overwrite argument is non-zero, setenv either will change the existing
value to newvalue or will delete the string name=value and add the
string name=newvalue.
If the newvalue pointer is NULL, all strings of the form name=value in
the environment list will be deleted.
The value of the pointer environ may change across a call to the setenv
function.
The setenv function will make copies of the strings associated with name
and newvalue.
The matching is case-insensitive; all lowercase letters are treated as
if they were in upper case.
Entries can also be added to the environment list with the DOS set
command or with the putenv or setenv functions. All entries in the
environment list can be obtained by using the getenv function.
To assign a string to a variable and place it in the environment list:
C>SET INCLUDE=C:\WATCOM\H
To see what variables are in the environment list, and their current
assignments:
C>SET
COMSPEC=C:\COMMAND.COM
PATH=C:\;C:\WATCOM
INCLUDE=C:\WATCOM\H
C>
The _setenv function is identical to setenv. Use _setenv for ANSI
naming conventions.
The _wsetenv function is a wide-character version of setenv that
operates with wide-character strings.
Returns:
The setenv function returns zero upon successful completion. Otherwise,
it will return a non-zero value and set errno to indicate the error.
Errors:
When an error has occurred, errno contains a value indicating the type
of error that has been detected.
ENOMEM
Not enough memory to allocate a new environment string.
Example:
The following will change the string assigned to INCLUDE and then
display the new string.
#include <stdio.h>
#include <stdlib.h>
#include <env.h>
void main()
{
char *path;
if( setenv( "INCLUDE", "D:\\WATCOM\\H", 1 ) == 0 )
if( (path = getenv( "INCLUDE" )) != NULL )
printf( "INCLUDE=%s\n", path );
}
Classification:
setenv is POSIX 1003.1, _setenv is not POSIX, _wsetenv is not POSIX
Systems:
setenv - All
_setenv - DOS, Windows, Win386, Win32, QNX/16, OS/2 1.x(all), OS/2-32
_wsetenv - DOS, Windows, Win386, Win32, QNX/16, OS/2 1.x(all), OS/2-32
See Also:
clearenv, exec Functions, getenv, putenv, _searchenv, spawn Functions,
system
See Also: clearenv
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