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)