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diff --git a/man1p/bg.1p b/man1p/bg.1p new file mode 100644 index 000000000..5fbf2fac3 --- /dev/null +++ b/man1p/bg.1p @@ -0,0 +1,205 @@ +.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved +.TH "BG" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual" +.\" bg +.SH NAME +bg \- run jobs in the background +.SH SYNOPSIS +.LP +\fBbg\fP \fB[\fP\fIjob_id\fP \fB...\fP\fB]\fP\fB\fP +.SH DESCRIPTION +.LP +If job control is enabled (see the description of \fIset\fP \fB-m\fP), +the +\fIbg\fP utility shall resume suspended jobs from the current environment +(see \fIShell +Execution Environment\fP ) by running them as background jobs. If +the job specified by \fIjob_id\fP is already a running +background job, the \fIbg\fP utility shall have no effect and shall +exit successfully. +.LP +Using \fIbg\fP 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 +\fIAsynchronous +Lists\fP . +.SH OPTIONS +.LP +None. +.SH OPERANDS +.LP +The following operand shall be supported: +.TP 7 +\fIjob_id\fP +Specify the job to be resumed as a background job. If no \fIjob_id\fP +operand is given, the most recently suspended job shall +be used. The format of \fIjob_id\fP is described in the Base Definitions +volume of IEEE\ Std\ 1003.1-2001, Section 3.203, Job Control Job ID. +.sp +.SH STDIN +.LP +Not used. +.SH INPUT FILES +.LP +None. +.SH ENVIRONMENT VARIABLES +.LP +The following environment variables shall affect the execution of +\fIbg\fP: +.TP 7 +\fILANG\fP +Provide a default value for the internationalization variables that +are unset or null. (See the Base Definitions volume of +IEEE\ Std\ 1003.1-2001, Section 8.2, Internationalization Variables +for +the precedence of internationalization variables used to determine +the values of locale categories.) +.TP 7 +\fILC_ALL\fP +If set to a non-empty string value, override the values of all the +other internationalization variables. +.TP 7 +\fILC_CTYPE\fP +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). +.TP 7 +\fILC_MESSAGES\fP +Determine the locale that should be used to affect the format and +contents of diagnostic messages written to standard +error. +.TP 7 +\fINLSPATH\fP +Determine the location of message catalogs for the processing of \fILC_MESSAGES +\&.\fP +.sp +.SH ASYNCHRONOUS EVENTS +.LP +Default. +.SH STDOUT +.LP +The output of \fIbg\fP shall consist of a line in the format: +.sp +.RS +.nf + +\fB"[%d] %s\\n", <\fP\fIjob-number\fP\fB>, <\fP\fIcommand\fP\fB> +\fP +.fi +.RE +.LP +where the fields are as follows: +.TP 7 +<\fIjob-number\fP> +A number that can be used to identify the job to the \fIwait\fP, \fIfg\fP, +and \fIkill\fP utilities. Using these utilities, the +job can be identified by prefixing the job number with \fB'%'\fP . +.TP 7 +<\fIcommand\fP> +The associated command that was given to the shell. +.sp +.SH STDERR +.LP +The standard error shall be used only for diagnostic messages. +.SH OUTPUT FILES +.LP +None. +.SH EXTENDED DESCRIPTION +.LP +None. +.SH EXIT STATUS +.LP +The following exit values shall be returned: +.TP 7 +\ 0 +Successful completion. +.TP 7 +>0 +An error occurred. +.sp +.SH CONSEQUENCES OF ERRORS +.LP +If job control is disabled, the \fIbg\fP utility shall exit with an +error and no job shall be placed in the background. +.LP +\fIThe following sections are informative.\fP +.SH APPLICATION USAGE +.LP +A job is generally suspended by typing the SUSP character (<control>-Z +on most systems); see the Base Definitions volume +of IEEE\ Std\ 1003.1-2001, Chapter 11, General Terminal Interface. +At that +point, \fIbg\fP 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 +.nf + +\fBstty tostop +\fP +.fi +.RE +.LP +A background job can be stopped with the command: +.sp +.RS +.nf + +\fBkill -s stop\fP \fIjob ID\fP +.fi +.RE +.LP +The \fIbg\fP 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 +.nf + +\fB\&... | xargs bg +(bg) +\fP +.fi +.RE +.LP +each \fIbg\fP operates in a different environment and does not share +its parent shell's understanding of jobs. For this reason, +\fIbg\fP is generally implemented as a shell regular built-in. +.SH EXAMPLES +.LP +None. +.SH RATIONALE +.LP +The extensions to the shell specified in this volume of IEEE\ Std\ 1003.1-2001 +have mostly been based on features +provided by the KornShell. The job control features provided by \fIbg\fP, +\fIfg\fP, and \fIjobs\fP 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 IEEE\ Std\ 1003.1-2001 to +maintain a degree of uniformity with the rest of the +KornShell features selected (such as the very popular command line +editing features). +.LP +The \fIbg\fP utility is expected to wrap its output if the output +exceeds the number of display columns. +.SH FUTURE DIRECTIONS +.LP +None. +.SH SEE ALSO +.LP +\fIAsynchronous Lists\fP , \fIfg\fP , \fIkill\fP() , \fIjobs\fP , +\fIwait\fP() +.SH COPYRIGHT +Portions of this text are reprinted and reproduced in electronic form +from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology +-- Portable Operating System Interface (POSIX), The Open Group Base +Specifications Issue 6, Copyright (C) 2001-2003 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 . |