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PROLOG
       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.


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 environment''; 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  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.


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.1‐2017,  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.


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  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).


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.1‐2017, 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
       1003.1-2017, 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 .