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diff --git a/man-pages-posix-2013/man1p/bg.1p b/man-pages-posix-2013/man1p/bg.1p new file mode 100644 index 0000000..44c09d3 --- /dev/null +++ b/man-pages-posix-2013/man1p/bg.1p @@ -0,0 +1,222 @@ +'\" et +.TH BG "1P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual" +.SH 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. + +.SH NAME +bg +\(em run jobs in the background +.SH SYNOPSIS +.LP +.nf +bg \fB[\fIjob_id\fR...\fB]\fR +.fi +.SH DESCRIPTION +If job control is enabled (see the description of +.IR set +.BR \(mim ), +the +.IR bg +utility shall resume suspended jobs from the current environment (see +.IR "Section 2.12" ", " "Shell Execution Environment") +by running them as background jobs. If the job specified by +.IR job_id +is already a running background job, the +.IR bg +utility shall have no effect and shall exit successfully. +.P +Using +.IR bg +to place a job into the background shall cause its process ID to become +``known in the current shell execution environment'', as if it had been +started as an asynchronous list; see +.IR "Section 2.9.3.1" ", " "Examples". +.SH OPTIONS +None. +.SH OPERANDS +The following operand shall be supported: +.IP "\fIjob_id\fR" 10 +Specify the job to be resumed as a background job. If no +.IR job_id +operand is given, the most recently suspended job shall be used. The +format of +.IR job_id +is described in the Base Definitions volume of POSIX.1\(hy2008, +.IR "Section 3.204" ", " "Job Control Job ID". +.SH STDIN +Not used. +.SH "INPUT FILES" +None. +.SH "ENVIRONMENT VARIABLES" +The following environment variables shall affect the execution of +.IR bg : +.IP "\fILANG\fP" 10 +Provide a default value for the internationalization variables that are +unset or null. (See the Base Definitions volume of POSIX.1\(hy2008, +.IR "Section 8.2" ", " "Internationalization Variables" +for the precedence of internationalization variables used to determine +the values of locale categories.) +.IP "\fILC_ALL\fP" 10 +If set to a non-empty string value, override the values of all the +other internationalization variables. +.IP "\fILC_CTYPE\fP" 10 +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). +.IP "\fILC_MESSAGES\fP" 10 +.br +Determine the locale that should be used to affect the format and +contents of diagnostic messages written to standard error. +.IP "\fINLSPATH\fP" 10 +Determine the location of message catalogs for the processing of +.IR LC_MESSAGES . +.SH "ASYNCHRONOUS EVENTS" +Default. +.SH STDOUT +The output of +.IR bg +shall consist of a line in the format: +.sp +.RS 4 +.nf +\fB +"[%d] %s\en", <\fIjob-number\fR>, <\fIcommand\fR> +.fi \fR +.P +.RE +.P +where the fields are as follows: +.IP "<\fIjob-number\fR>" 10 +A number that can be used to identify the job to the +.IR wait , +.IR fg , +and +.IR kill +utilities. Using these utilities, the job can be identified by +prefixing the job number with +.BR '%' . +.IP "<\fIcommand\fR>" 10 +The associated command that was given to the shell. +.SH STDERR +The standard error shall be used only for diagnostic messages. +.SH "OUTPUT FILES" +None. +.SH "EXTENDED DESCRIPTION" +None. +.SH "EXIT STATUS" +The following exit values shall be returned: +.IP "\00" 6 +Successful completion. +.IP >0 6 +An error occurred. +.SH "CONSEQUENCES OF ERRORS" +If job control is disabled, the +.IR bg +utility shall exit with an error and no job shall be placed in the +background. +.LP +.IR "The following sections are informative." +.SH "APPLICATION USAGE" +A job is generally suspended by typing the SUSP character +(<control>\(hyZ on most systems); see the Base Definitions volume of POSIX.1\(hy2008, +.IR "Chapter 11" ", " "General Terminal Interface". +At that point, +.IR bg +can put the job into the background. This is most effective when the +job is expecting no terminal input and its output has been redirected +to non-terminal files. A background job can be forced to stop when it +has terminal output by issuing the command: +.sp +.RS 4 +.nf +\fB +stty tostop +.fi \fR +.P +.RE +.P +A background job can be stopped with the command: +.sp +.RS 4 +.nf +\fB +kill \(mis stop \fIjob ID\fR +.fi \fR +.P +.RE +.P +The +.IR bg +utility does not work as expected when it is operating in its own +utility execution environment because that environment has no suspended +jobs. In the following examples: +.sp +.RS 4 +.nf +\fB +\&... | xargs bg +(bg) +.fi \fR +.P +.RE +.P +each +.IR bg +operates in a different environment and does not share its parent +shell's understanding of jobs. For this reason, +.IR bg +is generally implemented as a shell regular built-in. +.SH EXAMPLES +None. +.SH RATIONALE +The extensions to the shell specified in this volume of POSIX.1\(hy2008 have mostly been based +on features provided by the KornShell. The job control features +provided by +.IR bg , +.IR fg , +and +.IR 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\(hy2008 to maintain a degree of +uniformity with the rest of the KornShell features selected (such as +the very popular command line editing features). +.P +The +.IR bg +utility is expected to wrap its output if the output exceeds the number +of display columns. +.SH "FUTURE DIRECTIONS" +None. +.SH "SEE ALSO" +.IR "Section 2.9.3.1" ", " "Examples", +.IR "\fIfg\fR\^", +.IR "\fIkill\fR\^", +.IR "\fIjobs\fR\^", +.IR "\fIwait\fR\^" +.P +The Base Definitions volume of POSIX.1\(hy2008, +.IR "Section 3.204" ", " "Job Control Job ID", +.IR "Chapter 8" ", " "Environment Variables", +.IR "Chapter 11" ", " "General Terminal Interface" +.SH 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 . |