Remove an environment variable.

#include <stdlib.h>

int unsetenv(const char *name);

Parameters

name

The name of the variable to remove.

value

The value of the variable to set.

overwrite

Determine whether an existing value is overwritten or not.

Remarks

The unsetenv function shall remove 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. The named argument shall not contain an '=' character. If the named variable does not exist in the current environment, the environment shall be unchanged and the function is considered to have completed successfully.

Return Values

0 (zero).

Success.

-1

Failure. The value of errno is set as follows:

EINVAL

The envname argument points to an empty string or points to a string containing an '=' character.

Requirements