удалить переменную среды (remove an environment variable)
Пролог (Prolog)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
Имя (Name)
unsetenv — remove an environment variable
Синопсис (Synopsis)
#include <stdlib.h>
int unsetenv(const char *name);
Описание (Description)
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.
The unsetenv() function shall update the list of pointers to
which environ points.
The unsetenv() function need not be thread-safe.
Возвращаемое значение (Return value)
Upon successful completion, zero shall be returned. Otherwise, -1
shall be returned, errno set to indicate the error, and the
environment shall be unchanged.
Ошибки (Error)
The unsetenv() function shall fail if:
EINVAL The name argument points to an empty string, or points to
a string containing an '=' character.
The following sections are informative.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
None.
Обоснование (Rationale)
Refer to the RATIONALE section in setenv(3p).
Будущие направления (Future directions)
None.
Смотри также (See also)
getenv(3p), setenv(3p)
The Base Definitions volume of POSIX.1‐2017, stdlib.h(0p),
sys_types.h(0p)
