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PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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FG(1P) POSIX Programmer's Manual FG(1P)
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.
fg — run jobs in the foreground
fg [job_id]
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.
None.
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.
Not used.
None.
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.
Default.
The fg utility shall write the command line of the job to
standard output in the following format:
"%s\n", <command>
The standard error shall be used only for diagnostic messages.
None.
None.
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
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.
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.
None.
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).
None.
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
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 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 .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 FG(1P)
Pages that refer to this page: bg(1p), jobs(1p)
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