установить атрибут экспорта для переменных (set the export attribute for variables)
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)
export — set the export attribute for variables
Синопсис (Synopsis)
export name[=word]...
export -p
Описание (Description)
The shell shall give the export attribute to the variables
corresponding to the specified names, which shall cause them to
be in the environment of subsequently executed commands. If the
name of a variable is followed by =word, then the value of that
variable shall be set to word.
The export special built-in shall support the Base Definitions
volume of POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
When -p is specified, export shall write to the standard output
the names and values of all exported variables, in the following
format:
"export %s=%s\n", <name>, <value>
if name is set, and:
"export %s\n", <name>
if name is unset.
The shell shall format the output, including the proper use of
quoting, so that it is suitable for reinput to the shell as
commands that achieve the same exporting results, except:
1. Read-only variables with values cannot be reset.
2. Variables that were unset at the time they were output need
not be reset to the unset state if a value is assigned to the
variable between the time the state was saved and the time at
which the saved output is reinput to the shell.
When no arguments are given, the results are unspecified.
Параметры (Options)
See the DESCRIPTION.
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)
See the DESCRIPTION.
STDERR S
The standard error shall be used only for diagnostic messages.
Выходные файлы (Output files)
None.
Расширенное описание (Extended description)
None.
Статус выхода (Exit)
0 All name operands were successfully exported.
>0 At least one name could not be exported, or the -p option
was specified and an error occurred.
Последствия ошибок (Consequences of errors)
Default.
The following sections are informative.
Использование в приложениях (Application usage)
Note that, unless X was previously marked readonly, the value of
"$?" after:
export X=$(false)
will be 0 (because export successfully set X to the empty string)
and that execution continues, even if set -e is in effect. In
order to detect command substitution failures, a user must
separate the assignment from the export, as in:
X=$(false)
export X
Примеры (Examples)
Export PWD and HOME variables:
export PWD HOME
Set and export the PATH variable:
export PATH=/local/bin:$PATH
Save and restore all exported variables:
export -p > temp-file
unset a lot of variables
... processing
. temp-file
Обоснование (Rationale)
Some historical shells use the no-argument case as the functional
equivalent of what is required here with -p. This feature was
left unspecified because it is not historical practice in all
shells, and some scripts may rely on the now-unspecified results
on their implementations. Attempts to specify the -p output as
the default case were unsuccessful in achieving consensus. The
-p option was added to allow portable access to the values that
can be saved and then later restored using; for example, a dot
script.
Будущие направления (Future directions)
None.
Смотри также (See also)
Section 2.14, Special Built-In Utilities
The Base Definitions volume of POSIX.1‐2017, Section 12.2,
Utility Syntax Guidelines
