72 lines
4.3 KiB
HTML
72 lines
4.3 KiB
HTML
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<!Converted with LaTeX2HTML 95.1 (Fri Jan 20 1995) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds >
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<HEAD>
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<TITLE>3.11.2 Foreground and background</TITLE>
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<meta name="description" value="3.11.2 Foreground and background">
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<meta name="resource-type" value="document">
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<BR> <HR><A NAME=tex2html3450 HREF="node135.html"><IMG ALIGN=BOTTOM ALT="next" SRC="next_motif.gif"></A> <A NAME=tex2html3448 HREF="node132.html"><IMG ALIGN=BOTTOM ALT="up" SRC="up_motif.gif"></A> <A NAME=tex2html3442 HREF="node133.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="previous_motif.gif"></A> <A NAME=tex2html3452 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="contents_motif.gif"></A> <A NAME=tex2html3453 HREF="node250.html"><IMG ALIGN=BOTTOM ALT="index" SRC="index_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME=tex2html3451 HREF="node135.html">3.11.3 Backgrounding and killing </A>
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<B>Up:</B> <A NAME=tex2html3449 HREF="node132.html">3.11 Job Control</A>
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<B> Previous:</B> <A NAME=tex2html3443 HREF="node133.html">3.11.1 Jobs and processes</A>
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<BR> <HR> <P>
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<H2><A NAME=SECTION005112000000000000000>3.11.2 Foreground and background</A></H2>
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<P>
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<A NAME=3409> </A>
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<A NAME=3410> </A>
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<A NAME=3411> </A>
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<A NAME=3412> </A>
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<A NAME=3413> </A>
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<A NAME=3414> </A>
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Jobs can either be in the <b>foreground</b> or in the <b>background</b>.
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There can only be one job in the foreground at any one time. The foreground
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job is the job which you interact with---it receives input from the keyboard
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and sends output to your screen. (Unless, of course, you have redirected
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input or output, as described in Section <A HREF="node119.html#secplumbing">3.8</A>). On the other
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hand, jobs in the background do not receive input from the terminal---in
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general, they run along quietly without need for interaction.
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<P>
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Some jobs take a long time to finish, and don't do anything
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interesting while they are running. Compiling programs is one such
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job, as is compressing a large file. There's no reason why you
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should sit around being bored while these jobs complete their tasks;
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you can just run them in the background. While the jobs are running
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in the background, you are free to run other programs.
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<P>
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<A NAME=3418> </A>
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Jobs may also be <b>suspended</b>. A suspended job is a job that
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is not currently running, but is temporarily stopped. After you
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suspend a job, you can tell the job to continue, in the foreground
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or the background as needed. Resuming a suspended job will not change
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the state of the job in any way---the job will continue to run where
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it left off.
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<P>
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<A NAME=3420> </A>
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<A NAME=3421> </A>
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Note that suspending a job is not equal to <em>interrupting</em>
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a job. When you interrupt a running process (by hitting your interrupt
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key, which is usually <IMG BORDER=0 ALIGN=BOTTOM ALT="" SRC="img190.gif">)<A NAME=tex2html640 HREF="footnode.html#3568"><IMG ALIGN=BOTTOM ALT="gif" SRC="foot_motif.gif"></A>,
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it kills the process, for good.
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Once the job is killed, there's no hope of resuming it; you'll have
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to re-run the command. Also note that some programs trap the interrupt,
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so that hitting <IMG BORDER=0 ALIGN=BOTTOM ALT="" SRC="img192.gif"> won't immediately kill the job. This is to
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allow the program to perform any necessary cleanup operations before exiting.
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In fact, some programs simply don't allow you to kill
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them with an interrupt at all.
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<P>
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<BR> <HR><A NAME=tex2html3450 HREF="node135.html"><IMG ALIGN=BOTTOM ALT="next" SRC="next_motif.gif"></A> <A NAME=tex2html3448 HREF="node132.html"><IMG ALIGN=BOTTOM ALT="up" SRC="up_motif.gif"></A> <A NAME=tex2html3442 HREF="node133.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="previous_motif.gif"></A> <A NAME=tex2html3452 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="contents_motif.gif"></A> <A NAME=tex2html3453 HREF="node250.html"><IMG ALIGN=BOTTOM ALT="index" SRC="index_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME=tex2html3451 HREF="node135.html">3.11.3 Backgrounding and killing </A>
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<B>Up:</B> <A NAME=tex2html3449 HREF="node132.html">3.11 Job Control</A>
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<B> Previous:</B> <A NAME=tex2html3443 HREF="node133.html">3.11.1 Jobs and processes</A>
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<BR> <HR> <P>
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<BR> <HR>
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<P><ADDRESS>
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<I>Matt Welsh <BR>
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mdw@sunsite.unc.edu</I>
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</ADDRESS>
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</BODY>
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