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.1‐2008, 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\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.1‐2008  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 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 .