заставить оболочку выйти (cause the shell to exit)
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)
exit — cause the shell to exit
Синопсис (Synopsis)
exit [n]
Описание (Description)
The exit utility shall cause the shell to exit from its current
execution environment with the exit status specified by the
unsigned decimal integer n. If the current execution environment
is a subshell environment, the shell shall exit from the subshell
environment with the specified exit status and continue in the
environment from which that subshell environment was invoked;
otherwise, the shell utility shall terminate with the specified
exit status. If n is specified, but its value is not between 0
and 255 inclusively, the exit status is undefined.
A trap on EXIT shall be executed before the shell terminates,
except when the exit utility is invoked in that trap itself, in
which case the shell shall exit immediately.
Параметры (Options)
None.
Операнды (Operands)
See the DESCRIPTION.
Стандартный ввод (Stdin)
Not used.
Входные файлы (Input files)
None.
Переменные окружения (Environment variables)
None.
Асинхронные события (Asynchronous events)
Default.
Стандартный вывод (Stdout)
Not used.
Стандартный вывод сообщений (Stderr)
The standard error shall be used only for diagnostic messages.
Выходные файлы (Output files)
None.
Расширенное описание (Extended description)
None.
Статус выхода (Exit)
The exit status shall be n, if specified, except that the
behavior is unspecified if n is not an unsigned decimal integer
or is greater than 255. Otherwise, the value shall be the exit
value of the last command executed, or zero if no command was
executed. When exit is executed in a trap action, the last
command is considered to be the command that executed immediately
preceding the trap action.
Последствия ошибок (Consequences of errors)
Default.
The following sections are informative.
Использование в приложениях (Application usage)
None.
Примеры (Examples)
Exit with a true value:
exit 0
Exit with a false value:
exit 1
Propagate error handling from within a subshell:
(
command1 || exit 1
command2 || exit 1
exec command3
) > outputfile || exit 1
echo "outputfile created successfully"
Обоснование (Rationale)
As explained in other sections, certain exit status values have
been reserved for special uses and should be used by applications
only for those purposes:
126 A file to be executed was found, but it was not an
executable utility.
127 A utility to be executed was not found.
>128 A command was interrupted by a signal.
The behavior of exit when given an invalid argument or unknown
option is unspecified, because of differing practices in the
various historical implementations. A value larger than 255 might
be truncated by the shell, and be unavailable even to a parent
process that uses waitid() to get the full exit value. It is
recommended that implementations that detect any usage error
should cause a non-zero exit status (or, if the shell is
interactive and the error does not cause the shell to abort,
store a non-zero value in "$?"), but even this was not done
historically in all shells.
Будущие направления (Future directions)
None.
Смотри также (See also)
Section 2.14, Special Built-In Utilities
