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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 |
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.1‐2008,
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.1‐2008, 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.1‐2008
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.1‐2008 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.1‐2008, 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, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) 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.unix.org/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 2013 FG(1P)
Pages that refer to this page: bg(1p), jobs(1p)