1FG(1P) POSIX Programmer's Manual FG(1P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 fg - run jobs in the foreground
13
15 fg [job_id]
16
18 If job control is enabled (see the description of set -m), the fg util‐
19 ity shall move a background job from the current environment (see Shell
20 Execution Environment ) into the foreground.
21 Using fg to place a job into the foreground shall remove its process ID
23 from the list of those "known in the current shell execution environ‐
24 ment''; see Asynchronous Lists .
25
27 None.
28
30 The following operand shall be supported:
31 job_id Specify the job to be run as a foreground job. If no job_id op‐
33 erand is given, the job_id for the job that was most recently
34 suspended, placed in the background, or run as a background job
35 shall be used. The format of job_id is described in the Base
36 Definitions volume of IEEE Std 1003.1-2001, Section 3.203, Job
37 Control Job ID.
38
41 Not used.
42
44 None.
45
47 The following environment variables shall affect the execution of fg:
48 LANG Provide a default value for the internationalization variables
50 that are unset or null. (See the Base Definitions volume of
51 IEEE Std 1003.1-2001, Section 8.2, Internationalization Vari‐
52 ables for the precedence of internationalization variables used
53 to determine the values of locale categories.)
54 LC_ALL If set to a non-empty string value, override the values of all
56 the other internationalization variables.
57 LC_CTYPE
59 Determine the locale for the interpretation of sequences of
60 bytes of text data as characters (for example, single-byte as
61 opposed to multi-byte characters in arguments).
62 LC_MESSAGES
64 Determine the locale that should be used to affect the format
65 and contents of diagnostic messages written to standard error.
66 NLSPATH
68 Determine the location of message catalogs for the processing of
69 LC_MESSAGES .
70
73 Default.
74
76 The fg utility shall write the command line of the job to standard out‐
77 put in the following format:
78 "%s\n", <command>
81
83 The standard error shall be used only for diagnostic messages.
84
86 None.
87
89 None.
90
92 The following exit values shall be returned:
93 0 Successful completion.
95 >0 An error occurred.
97
100 If job control is disabled, the fg utility shall exit with an error and
101 no job shall be placed in the foreground.
102 The following sections are informative.
104
106 The fg utility does not work as expected when it is operating in its
107 own utility execution environment because that environment has no
108 applicable jobs to manipulate. See the APPLICATION USAGE section for bg
109 . For this reason, fg is generally implemented as a shell regular
110 built-in.
111
113 None.
114
116 The extensions to the shell specified in this volume of
117 IEEE Std 1003.1-2001 have mostly been based on features provided by the
118 KornShell. The job control features provided by bg, fg, and jobs are
119 also based on the KornShell. The standard developers examined the char‐
120 acteristics of the C shell versions of these utilities and found that
121 differences exist. Despite widespread use of the C shell, the KornShell
122 versions were selected for this volume of IEEE Std 1003.1-2001 to main‐
123 tain a degree of uniformity with the rest of the KornShell features
124 selected (such as the very popular command line editing features).
125
127 None.
128
130 Asynchronous Lists, Shell Execution Environment, bg, kill(), jobs,
131 wait()
132
134 Portions of this text are reprinted and reproduced in electronic form
135 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
136 -- Portable Operating System Interface (POSIX), The Open Group Base
137 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
138 Electrical and Electronics Engineers, Inc and The Open Group. In the
139 event of any discrepancy between this version and the original IEEE and
140 The Open Group Standard, the original IEEE and The Open Group Standard
141 is the referee document. The original Standard can be obtained online
142 at http://www.opengroup.org/unix/online.html .
143IEEE/The Open Group 2003 FG(1P)