This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

       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.

       Default.

       If job control is disabled, the fg utility shall exit with an error and no job shall  be  placed  in  the
       foreground.

       Thefollowingsectionsareinformative.

       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 .

IEEE/The Open Group                                   2017                                            FG(1POSIX)

       If  job  control  is  enabled (see the description of set-m), the fg utility shall move a background job
       from the current environment (see Section2.12, ShellExecutionEnvironment) 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 Section2.9.3.1, Examples.

       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, Section8.2, InternationalizationVariables 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.

       None.

       The following exit values shall be returned:

        0    Successful completion.

       >0    An error occurred.

       None.

       None.

       None.

       fg — run jobs in the foreground

       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, Section3.204, JobControlJobID.

       None.

       None.

       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.

       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).

Section2.9.3.1, Examples, Section2.12, ShellExecutionEnvironment, bg, kill, jobs, wait

       The  Base  Definitions  volume of POSIX.1‐2017, Section3.204, JobControlJobID, Chapter8, EnvironmentVariables

       The standard error shall be used only for diagnostic messages.

       Not used.

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

           "%s\n", <command>

       fg [job_id]