UNSETENV(3C) Standard C Library Functions UNSETENV(3C)

NAME

unsetenv - remove an environment variable

SYNOPSIS

#include <stdlib.h>

int unsetenv(const char *name);

DESCRIPTION

The unsetenv() function removes an environment variable from the
environment of the calling process. The name argument points to a string
that is the name of the variable to be removed. The named argument cannot
contain an '=' character. If the named variable does not exist in the
current environment, the environment is unchanged and the function is
considered to have completed successfully.


If the application modifies environ or the pointers to which it points,
the behavior of unsetenv() is undefined. The unsetenv() function updates
the list of pointers to which environ points.

RETURN VALUES

Upon successful completion, 0 is returned. Otherwise, -1 is returned,
errno set to indicate the error, and the environment is left unchanged.

ERRORS

The unsetenv() function will fail if:

EINVAL
The name argument is a null pointer, points to an empty string,
or points to a string containing an '=' character.

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+
|MT-Level | MT-Safe |
+--------------------+-----------------+

SEE ALSO

clearenv(3C), getenv(3C), setenv(3C), attributes(7), standards(7)


December 20, 2014 UNSETENV(3C)