posix man page for fg

FG(1P)							     POSIX Programmer's Manual							    FG(1P)

PROLOG
       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

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
       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 envi-
       ronment''; see Section 2.9.3.1, Examples.

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  sus-
		 pended, placed in the background, or run as a background job shall be used. The format of job_id is described in the Base Defini-
		 tions volume of POSIX.1-2008, Section 3.204, 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
		 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.

ASYNCHRONOUS EVENTS
       Default.

STDOUT
       The fg utility shall write the command line of the job to standard output in the following format:

	   "%s
", <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 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).

FUTURE DIRECTIONS
       None.

SEE ALSO
       Section 2.9.3.1, Examples, Section 2.12, Shell Execution Environment, bg, kill, jobs, wait

       The Base Definitions volume of POSIX.1-2008, Section 3.204, Job Control Job ID, Chapter 8, Environment Variables

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition, Standard for Information Technol-
       ogy -- 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 Stan-
       dard 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)