Интерактивная система просмотра системных руководств (man-ов)
fg (1)
fg (1) ( Solaris man: Команды и прикладные программы пользовательского уровня )
fg (1) ( FreeBSD man: Команды и прикладные программы пользовательского уровня )
fg (1) ( Linux man: Команды и прикладные программы пользовательского уровня )
>> fg (1) ( POSIX man: Команды и прикладные программы пользовательского уровня )
NAME
fg - run jobs in the foreground
SYNOPSIS
fg[job_id]
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 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 Asynchronous Lists .
OPTIONS
None.
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 IEEE Std 1003.1-2001,
Section 3.203, Job Control Job ID.
STDIN
Not used.
INPUT FILES
None.
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
IEEE Std 1003.1-2001, 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
.
ASYNCHRONOUS EVENTS
Default.
STDOUT
The fg utility shall write the command line of the job to standard
output in the following format:
"%s\n", <command>
STDERR
The standard error shall be used only for diagnostic messages.
OUTPUT FILES
None.
EXTENDED DESCRIPTION
None.
EXIT STATUS
The following exit values shall be returned:
0
Successful completion.
>0
An error occurred.
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.
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 . For this
reason, fg is generally implemented as a shell regular built-in.
EXAMPLES
None.
RATIONALE
The extensions to the shell specified in this volume of IEEE Std 1003.1-2001
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 IEEE Std 1003.1-2001 to
maintain a degree of uniformity with the rest of the
KornShell features selected (such as the very popular command line
editing features).
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
