unsetenv() — Delete an environment variable
Standards
Standards / Extensions | C or C++ | Dependencies |
---|---|---|
Single UNIX Specification, version 3 |
both | z/OS V1R7 |
Format
#define _UNIX03_SOURCE
#include <stdlib.h>
int unsetenv(const char *name);
General description
unsetenv() deletes an environment variable from the environment of the calling process. The name argument points to a string, which is the name of the variable to be removed. If the string pointed to by name contains an '=' character, unsetenv() will fail. If the named variable does not exist in the current environment, the environment will not be changed and unsetenv() will succeed.
Returned value
If successful, unsetenv()
returns 0. If unsuccessful, unsetenv() returns -1 and sets errno to
indicate the error.
- EINVAL – The name argument is a null pointer, points to an empty string, or points to a string containing an '=' character.
Related information
- "Using Environment Variables" in the z/OS XL C/C++ Programming Guide.
- stdlib.h
- clearenv() — Clear environment variables
- getenv() — Get value of environment variables
- __getenv() — Get an environment variable
- putenv() — Change or add an environment variable
- setenv() — Add, delete, and change environment variables