1FG(P) POSIX Programmer's Manual FG(P)
2
6 fg - run jobs in the foreground
7
9 fg [job_id]
10
12 If job control is enabled (see the description of set -m), the fg util‐
13 ity shall move a background job from the current environment (see Shell
14 Execution Environment ) into the foreground.
15 Using fg to place a job into the foreground shall remove its process ID
17 from the list of those "known in the current shell execution environ‐
18 ment''; see Asynchronous Lists .
19
21 None.
22
24 The following operand shall be supported:
25 job_id Specify the job to be run as a foreground job. If no job_id op‐
27 erand is given, the job_id for the job that was most recently
28 suspended, placed in the background, or run as a background job
29 shall be used. The format of job_id is described in the Base
30 Definitions volume of IEEE Std 1003.1-2001, Section 3.203, Job
31 Control Job ID.
32
35 Not used.
36
38 None.
39
41 The following environment variables shall affect the execution of fg:
42 LANG Provide a default value for the internationalization variables
44 that are unset or null. (See the Base Definitions volume of
45 IEEE Std 1003.1-2001, Section 8.2, Internationalization Vari‐
46 ables for the precedence of internationalization variables used
47 to determine the values of locale categories.)
48 LC_ALL If set to a non-empty string value, override the values of all
50 the other internationalization variables.
51 LC_CTYPE
53 Determine the locale for the interpretation of sequences of
54 bytes of text data as characters (for example, single-byte as
55 opposed to multi-byte characters in arguments).
56 LC_MESSAGES
58 Determine the locale that should be used to affect the format
59 and contents of diagnostic messages written to standard error.
60 NLSPATH
62 Determine the location of message catalogs for the processing of
63 LC_MESSAGES .
64
67 Default.
68
70 The fg utility shall write the command line of the job to standard out‐
71 put in the following format:
72 "%s\n", <command>
75
77 The standard error shall be used only for diagnostic messages.
78
80 None.
81
83 None.
84
86 The following exit values shall be returned:
87 0 Successful completion.
89 >0 An error occurred.
91
94 If job control is disabled, the fg utility shall exit with an error and
95 no job shall be placed in the foreground.
96 The following sections are informative.
98
100 The fg utility does not work as expected when it is operating in its
101 own utility execution environment because that environment has no
102 applicable jobs to manipulate. See the APPLICATION USAGE section for bg
103 . For this reason, fg is generally implemented as a shell regular
104 built-in.
105
107 None.
108
110 The extensions to the shell specified in this volume of
111 IEEE Std 1003.1-2001 have mostly been based on features provided by the
112 KornShell. The job control features provided by bg, fg, and jobs are
113 also based on the KornShell. The standard developers examined the char‐
114 acteristics of the C shell versions of these utilities and found that
115 differences exist. Despite widespread use of the C shell, the KornShell
116 versions were selected for this volume of IEEE Std 1003.1-2001 to main‐
117 tain a degree of uniformity with the rest of the KornShell features
118 selected (such as the very popular command line editing features).
119
121 None.
122
124 Asynchronous Lists , Shell Execution Environment , bg , kill() , jobs ,
125 wait()
126
128 Portions of this text are reprinted and reproduced in electronic form
129 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
130 -- Portable Operating System Interface (POSIX), The Open Group Base
131 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
132 Electrical and Electronics Engineers, Inc and The Open Group. In the
133 event of any discrepancy between this version and the original IEEE and
134 The Open Group Standard, the original IEEE and The Open Group Standard
135 is the referee document. The original Standard can be obtained online
136 at http://www.opengroup.org/unix/online.html .
137IEEE/The Open Group 2003 FG(P)