запускать задания на переднем плане (run jobs in the foreground)
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)
fg — run jobs in the foreground
Синопсис (Synopsis)
fg [job_id]
Описание (Description)
If job control is enabled (see the description of set -m), the fg
utility shall move a background job from the current environment
(see Section 2.12, Shell Execution Environment) into the
foreground.
Using fg to place a job into the foreground shall remove its
process ID from the list of those ``known in the current shell
execution environment''; see Section 2.9.3.1, Examples.
Параметры (Options)
None.
Операнды (Operands)
The following operand shall be supported:
job_id Specify the job to be run as a foreground job. If no
job_id operand is given, the job_id for the job that
was most recently suspended, placed in the background,
or run as a background job shall be used. The format of
job_id is described in the Base Definitions volume of
POSIX.1‐2017, Section 3.204, Job Control Job ID.
Стандартный ввод (Stdin)
Not used.
Входные файлы (Input files)
None.
Переменные окружения (Environment variables)
The following environment variables shall affect the execution of
fg:
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base
Definitions volume of POSIX.1‐2017, Section 8.2,
Internationalization Variables for the precedence of
internationalization variables used to determine the
values of locale categories.)
LC_ALL If set to a non-empty string value, override the values
of all the other internationalization variables.
LC_CTYPE Determine the locale for the interpretation of
sequences of bytes of text data as characters (for
example, single-byte as opposed to multi-byte
characters in arguments).
LC_MESSAGES
Determine the locale that should be used to affect the
format and contents of diagnostic messages written to
standard error.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
Асинхронные события (Asynchronous events)
Default.
Стандартный вывод (Stdout)
The fg utility shall write the command line of the job to
standard output in the following format:
"%s\n", <command>
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 following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
Последствия ошибок (Consequences of errors)
If job control is disabled, the fg utility shall exit with an
error and no job shall be placed in the foreground.
The following sections are informative.
Использование в приложениях (Application usage)
The fg utility does not work as expected when it is operating in
its own utility execution environment because that environment
has no applicable jobs to manipulate. See the APPLICATION USAGE
section for bg(1p). For this reason, fg is generally implemented
as a shell regular built-in.
Примеры (Examples)
None.
Обоснование (Rationale)
The extensions to the shell specified in this volume of
POSIX.1‐2017 have mostly been based on features provided by the
KornShell. The job control features provided by bg, fg, and jobs
are also based on the KornShell. The standard developers examined
the characteristics of the C shell versions of these utilities
and found that differences exist. Despite widespread use of the C
shell, the KornShell versions were selected for this volume of
POSIX.1‐2017 to maintain a degree of uniformity with the rest of
the KornShell features selected (such as the very popular command
line editing features).
Будущие направления (Future directions)
None.
Смотри также (See also)
Section 2.9.3.1, Examples, Section 2.12, Shell Execution
Environment, bg(1p), kill(1p), jobs(1p), wait(1p)
The Base Definitions volume of POSIX.1‐2017, Section 3.204, Job
Control Job ID, Chapter 8, Environment Variables
