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<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 39] Time and Performance</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="1998-08-04T21:50:10Z"><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="part06.htm"TITLE="VI. Managing Processes "><LINKREL="prev"HREF="ch38_18.htm"TITLE="38.18 nohup "><LINKREL="next"HREF="ch39_02.htm"TITLE="39.2 Timing Programs "></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="ch38_18.htm"TITLE="38.18 nohup "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 38.18 nohup "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1">Chapter 39</FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch39_02.htm"TITLE="39.2 Timing Programs "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 39.2 Timing Programs "BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="CHAPTER"><H1CLASS="chapter"><ACLASS="title"NAME="UPT-CHP-39">39. Time and Performance</A></H1><DIVCLASS="htmltoc"><P><B>Contents:</B><BR><ACLASS="sect1"HREF="#UPT-ART-7784"TITLE="39.1 Which Time Is It? ">Which Time Is It? </A><BR><ACLASS="sect1"HREF="ch39_02.htm"TITLE="39.2 Timing Programs ">Timing Programs </A><BR><ACLASS="sect1"HREF="ch39_03.htm"TITLE="39.3 The csh time variable ">The csh time variable </A><BR><ACLASS="sect1"HREF="ch39_04.htm"TITLE="39.4 Average Command Runtimes with runtime ">Average Command Runtimes with runtime </A><BR><ACLASS="sect1"HREF="ch39_05.htm"TITLE="39.5 Why Is the System So Slow? ">Why Is the System So Slow? </A><BR><ACLASS="sect1"HREF="ch39_06.htm"TITLE="39.6 lastcomm: What Commands Are Running and How Long Do They Take?">lastcomm: What Commands Are Running and How Long Do They Take?</A><BR><ACLASS="sect1"HREF="ch39_07.htm"TITLE="39.7 Checking System Load: uptime ">Checking System Load: uptime </A><BR><ACLASS="sect1"HREF="ch39_08.htm"TITLE="39.8 A Big Environment Can Slow You Down ">A Big Environment Can Slow You Down </A><BR><ACLASS="sect1"HREF="ch39_09.htm"TITLE='39.9 Know When to Be "nice" to OTher Users...and WhenNot to'>Know When to Be "nice" to OTher Users...and WhenNot to</A><BR><ACLASS="sect1"HREF="ch39_10.htm"TITLE="39.10 A nice Gotcha ">A nice Gotcha </A><BR><ACLASS="sect1"HREF="ch39_11.htm"TITLE="39.11 Changing a Job's Priority Under BSD UNIX ">Changing a Job's Priority Under BSD UNIX </A><BR><ACLASS="sect1"HREF="ch39_12.htm"TITLE="39.12 What Makes Your Computer Slow? How Do You Fix It?">What Makes Your Computer Slow? How Do You Fix It?</A></P><P></P></DIV><DIVCLASS="sect1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-7784">39.1 Which Time Is It? </A></H2><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-43485"></A><ACLASS="indexterm"NAME="AUTOID-43488"></A>When we talk about "time" on UNIX systems, we could be talking abouttwo things:</P><OLCLASS="orderedlist"><LICLASS="listitem"><PCLASS="para">What time it is, as shown by the<SPANCLASS="link"><EMCLASS="emphasis">date</EM> (<ACLASS="linkend"HREF="ch51_10.htm"TITLE="The date Command ">51.10</A>)</SPAN>command, and recorded incountless ways - as file creation and modification times, as the timeof last login, and so on.</P></LI><LICLASS="listitem"><PCLASS="para">How long things take.</P></LI></OL><PCLASS="para">This chapter is concerned with the latter. It talks about how longprograms take to run, what makes them faster or slower, and what youcan (or more often can't) do about it.</P><DIVCLASS="sect1info"><PCLASS="SECT1INFO">- <SPANCLASS="authorinitials">TOR</SPAN></P></DIV></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="ch38_18.htm"TITLE="38.18 nohup "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 38.18 nohup "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="ch39_02.htm"TITLE="39.2 Timing Programs "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 39.2 Timing Programs "BORDER="0"></A></TD></TR><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172">38.18 nohup </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">39.2 Timing Programs </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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