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<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 40] 40.2 Waiting a Little While: sleep </TITLE><METANAME="DC.title"CONTENT="UNIX Power Tools"><METANAME="DC.creator"CONTENT="Jerry Peek, Tim O'Reilly & Mike Loukides"><METANAME="DC.publisher"CONTENT="O'Reilly & Associates, Inc."><METANAME="DC.date"CONTENT="1998-08-04T21:50:32Z"><METANAME="DC.type"CONTENT="Text.Monograph"><METANAME="DC.format"CONTENT="text/html"SCHEME="MIME"><METANAME="DC.source"CONTENT="1-56592-260-3"SCHEME="ISBN"><METANAME="DC.language"CONTENT="en-US"><METANAME="generator"CONTENT="Jade 1.1/O'Reilly DocBook 3.0 to HTML 4.0"><LINKREV="made"HREF="mailto:online-books@oreilly.com"TITLE="Online Books Comments"><LINKREL="up"HREF="ch40_01.htm"TITLE="40. Delayed Execution"><LINKREL="prev"HREF="ch40_01.htm"TITLE="40.1 Off-Peak Job Submission "><LINKREL="next"HREF="ch40_03.htm"TITLE="40.3 The at Command "></HEAD><BODYBGCOLOR="#FFFFFF"TEXT="#000000"><DIVCLASS="htmlnav"><H1><IMGSRC="gifs/smbanner.gif"ALT="UNIX Power Tools"USEMAP="#srchmap"BORDER="0"></H1><MAPNAME="srchmap"><AREASHAPE="RECT"COORDS="0,0,466,58"HREF="index.htm"ALT="UNIX Power Tools"><AREASHAPE="RECT"COORDS="467,0,514,18"HREF="jobjects/fsearch.htm"ALT="Search this book"></MAP><TABLEWIDTH="515"BORDER="0"CELLSPACING="0"CELLPADDING="0"><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch40_01.htm"TITLE="40.1 Off-Peak Job Submission "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 40.1 Off-Peak Job Submission "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1">Chapter 40<BR>Delayed Execution</FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch40_03.htm"TITLE="40.3 The at Command "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 40.3 The at Command "BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="SECT1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-2030">40.2 Waiting a Little While: sleep </A></H2><TABLECLASS="para.programreference"BORDER="1"><TR><THVALIGN="TOP"><ACLASS="programreference"HREF="examples/index.htm"TITLE="sleep">sleep</A><BR><ACLASS="programreference"HREF="examples/index.htm"TITLE="sleep">sleep</A><BR></TH><TDVALIGN="TOP"><ACLASS="indexterm"NAME="AUTOID-44456"></A>The <EMCLASS="emphasis">sleep</EM> command waits.That's all it does.(GNU versions are usually loaded with features, but the <EMCLASS="emphasis">sleep</EM>on the disc doesn't do more than the standard version.)So, what good is it?</TD></TR></TABLE><ULCLASS="itemizedlist"><LICLASS="listitem"><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-44465"></A>A quick-and-dirty reminder service when you don't have<SPANCLASS="link"><EMCLASS="emphasis">leave</EM> (<ACLASS="linkend"HREF="ch48_05.htm"TITLE="leave: A Maddening Aid to Quitting on Time ">48.5</A>)</SPAN>.This will print the message <CODECLASS="literal">Time to go now....</CODE> in 10 minutes(600 seconds):</P><PCLASS="para"><TABLECLASS="screen.co"BORDER="1"><TR><THVALIGN="TOP"><PRECLASS="calloutlist"><ACLASS="co"HREF="ch13_07.htm"TITLE="13.7 The () Subshell Operators ">( ) &</A> <ACLASS="co"HREF="ch08_05.htm"TITLE="8.5 Command-Line Evaluation ">;</A> </PRE></TH><TDVALIGN="TOP"><PRECLASS="screen">%<CODECLASS="userinput"><B> (sleep 600; echo Time to go now....) &</B></CODE></PRE></TD></TR></TABLE></P><PCLASS="para"></P></LI><LICLASS="listitem"><PCLASS="para">You can't use<SPANCLASS="link"><EMCLASS="emphasis">at</EM> (<ACLASS="linkend"HREF="ch40_03.htm"TITLE="The at Command ">40.3</A>)</SPAN>and you have to run a job later (say, three hours):</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>(sleep 10800; someprog) &</B></CODE></PRE></BLOCKQUOTE></P><PCLASS="para"></P></LI><LICLASS="listitem"><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-44486"></A>To watch a program (usually a shell script) that's running in the backgroundand see what processes it runs:</P><PCLASS="para"><TABLECLASS="screen.co"BORDER="1"><TR><THVALIGN="TOP"><PRECLASS="calloutlist"> <ACLASS="co"HREF="ch11_07.htm"TITLE="11.7 History Substitutions ">!!</A> </PRE></TH><TDVALIGN="TOP"><PRECLASS="screen">% <CODECLASS="userinput"><B>prog</B></CODE> &[1] 12345% <CODECLASS="userinput"><B>sleep 5;ps</B></CODE> PID TT STAT TIME COMMAND18305 p4 S 0:01 -csh (csh)18435 p4 S 0:00 /bin/sh prog18437 p4 D 0:00 /bin/sort -r temp18438 p4 R 0:00 ps% <CODECLASS="userinput"><B>!!;!!;!!;!!;!!</B></CODE>sleep 5; ps; sleep 5; ps; sleep 5; ps; sleep 5; ps; sleep 5; ps PID TT STAT TIME COMMAND ... <ICLASS="lineannotation">...5 seconds pass...</I> PID TT STAT TIME COMMAND ...</PRE></TD></TR></TABLE></P><PCLASS="para"></P></LI><LICLASS="listitem"><PCLASS="para">When you're running a series of commands that could swamp the computer,give it time to catch up.For instance, the<SPANCLASS="link"><EMCLASS="emphasis">mail</EM> (<ACLASS="linkend"HREF="ch01_33.htm"TITLE="UNIX Networking and Communications ">1.33</A>)</SPAN>program starts background processes todeliver the mail.If you're sending a bunch of form letters, sleep five or ten secondsafter each one:</P><PCLASS="para"><TABLECLASS="screen.co"BORDER="1"><TR><THVALIGN="TOP"><PRECLASS="calloutlist"><ACLASS="co"HREF="ch09_11.htm"TITLE="9.11 Repeating a Command with a foreach Loop ">foreach</A> </PRE></TH><TDVALIGN="TOP"><PRECLASS="screen">% <CODECLASS="userinput"><B>foreach name (`cat people`)</B></CODE>? <CODECLASS="userinput"><B>formltrprog $name | mail $name</B></CODE>? <CODECLASS="userinput"><B>sleep 10</B></CODE>? <CODECLASS="userinput"><B>end</B></CODE></PRE></TD></TR></TABLE></P><PCLASS="para">Or, to send print jobs while you're at lunch - but give other people achance to print between yours:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>lp bigfile1;sleep 600;lp bigfile2;sleep 600;lp bigfile3</B></CODE></PRE></BLOCKQUOTE></P></LI></UL><DIVCLASS="sect1info"><PCLASS="SECT1INFO">- <SPANCLASS="authorinitials">JP</SPAN></P></DIV></DIV><DIVCLASS="htmlnav"><P></P><HRALIGN="LEFT"WIDTH="515"TITLE="footer"><TABLEWIDTH="515"BORDER="0"CELLSPACING="0"CELLPADDING="0"><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch40_01.htm"TITLE="40.1 Off-Peak Job Submission "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 40.1 Off-Peak Job Submission "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><ACLASS="book"HREF="index.htm"TITLE="UNIX Power Tools"><IMGSRC="gifs/txthome.gif"SRC="gifs/txthome.gif"ALT="UNIX Power Tools"BORDER="0"></A></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch40_03.htm"TITLE="40.3 The at Command "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 40.3 The at Command "BORDER="0"></A></TD></TR><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172">40.1 Off-Peak Job Submission </TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><ACLASS="index"HREF="index/idx_0.htm"TITLE="Book Index"><IMGSRC="gifs/index.gif"SRC="gifs/index.gif"ALT="Book Index"BORDER="0"></A></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172">40.3 The at Command </TD></TR></TABLE><HRALIGN="LEFT"WIDTH="515"TITLE="footer"><IMGSRC="gifs/smnavbar.gif"SRC="gifs/smnavbar.gif"USEMAP="#map"BORDER="0"ALT="The UNIX CD Bookshelf Navigation"><MAPNAME="map"><AREASHAPE="RECT"COORDS="0,0,73,21"HREF="../index.htm"ALT="The UNIX CD Bookshelf"><AREASHAPE="RECT"COORDS="74,0,163,21"HREF="index.htm"ALT="UNIX Power Tools"><AREASHAPE="RECT"COORDS="164,0,257,21"HREF="../unixnut/index.htm"ALT="UNIX in a Nutshell"><AREASHAPE="RECT"COORDS="258,0,321,21"HREF="../vi/index.htm"ALT="Learning the vi Editor"><AREASHAPE="RECT"COORDS="322,0,378,21"HREF="../sedawk/index.htm"ALT="sed & awk"><AREASHAPE="RECT"COORDS="379,0,438,21"HREF="../ksh/index.htm"ALT="Learning the Korn Shell"><AREASHAPE="RECT"COORDS="439,0,514,21"HREF="../lrnunix/index.htm"ALT="Learning the UNIX Operating System"></MAP></DIV></BODY></HTML>⌨️ 快捷键说明
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