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
If job control is enabled (see the description of set −m
utility shall move a background job from the current environment
(see Section 2.12
, Shell Execution Environment
) into the
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 188.8.131.52
The following operand shall be supported:
- 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.
The following environment variables shall affect the execution of fg
- 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.)
- If set to a non-empty string value, override the values of
all the other internationalization variables.
- 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).
Determine the locale that should be used to affect the format and contents
of diagnostic messages written to standard error.
- Determine the location of message catalogs for the
processing of LC_MESSAGES.
utility shall write the command line of the job to standard output
in the following format:
The standard error shall be used only for diagnostic messages.
The following exit values shall be returned:
- Successful completion.
- 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.
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
this reason, fg
is generally implemented as a shell regular built-in.
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
, 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
, Section 2.12
, Shell Execution
The Base Definitions volume of POSIX.1‐2008, Section 3.204
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 .
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