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<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 6] 6.7 What Time Is It in Japan? </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="1998-10-23T15:38:05Z"><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="ch06_01.htm"TITLE="6. Shell and Environment Variables"><LINKREL="prev"HREF="ch06_06.htm"TITLE="6.6 The TZ Environment Variable "><LINKREL="next"HREF="ch06_08.htm"TITLE="6.8 Shell Variables "></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="ch06_06.htm"TITLE="6.6 The TZ Environment Variable "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 6.6 The TZ Environment Variable "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1">Chapter 6<BR>Shell and Environment Variables</FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch06_08.htm"TITLE="6.8 Shell Variables "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 6.8 Shell Variables "BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="SECT1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-7926">6.7 What Time Is It in Japan? </A></H2><TABLECLASS="para.programreference"BORDER="1"><TR><THVALIGN="TOP"><ACLASS="programreference"HREF="examples/index.htm"TITLE="tm">tm</A><BR></TH><TDVALIGN="TOP">The<SPANCLASS="link"><EMCLASS="emphasis">TZ</EM> (<ACLASS="linkend"HREF="ch06_06.htm"TITLE="The TZ Environment Variable ">6.6</A>)</SPAN>environment variablehas some convenient uses, particularly if you do business withpeople scattered all over the globe. Let's say you want to call yourtrading partner in Japan to find out how the stock exchange is doing.But you want to know, first, whether or not the market has opened (orwhether your partner is even awake!).You can use a shell script called <EMCLASS="emphasis">tm</EM> that does this for you.Or you can (quickly) set <EMCLASS="emphasis">TZ</EM> to"Japan," print the date, and reset <EMCLASS="emphasis">TZ</EM>.Here are examples - including resetting <EMCLASS="emphasis">TZ</EM><SPANCLASS="link">temporarily (<ACLASS="linkend"HREF="ch06_10.htm"TITLE="Running a Command with a Temporarily Different Environment ">6.10</A>)</SPAN>in the Bourne and C shells:</TD></TR></TABLE><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>date</B></CODE>Tue Mar 4 20:48:58 EST 1997% <CODECLASS="userinput"><B>tm Japan</B></CODE>Wed Mar 5 10:48:07 JST 1997 %(<CODECLASS="userinput"><B>setenv TZ Japan; date)</B></CODE>Wed Mar 5 10:48:13 JST 1997$ <CODECLASS="userinput"><B>TZ=Japan date</B></CODE>Wed Mar 5 10:48:22 JST 1997</PRE></TD></TR></TABLE></P><PCLASS="para">It's 10 A.M. over there; should be a good time to call.Of course, the argument to <EMCLASS="emphasis">TZ</EM> has to be one of the time zone files in<EMCLASS="emphasis">/usr/lib/zoneinfo</EM>. One "gotcha": all the "useful" files in thisdirectory begin with uppercase letters. If you set <EMCLASS="emphasis">TZ</EM> to "japan,"you'll get the Greenwich mean time - which is only about nine hours off!The <EMCLASS="emphasis">tm</EM> script solves this by complaining if it can't find thetimezone file.</P><PCLASS="para">Another problem you may have is figuring out just what time zone isright for some parts of the world.For example, unless you know yourgeography fairly well, you might have trouble figuring out that theappropriate <EMCLASS="emphasis">TZ</EM> setting for Sydney, Australia is <EMCLASS="emphasis">Australia/NSW</EM>(New South Wales), while Perth is <EMCLASS="emphasis">Australia/West</EM>.On some systems, though, the timezone files include major cities.If you run <EMCLASS="emphasis">tm</EM> with no time zone, it will list the time zone names.<ACLASS="indexterm"NAME="AUTOID-6200"></A><ACLASS="indexterm"NAME="AUTOID-6201"></A></P><DIVCLASS="sect1info"><PCLASS="SECT1INFO">- <SPANCLASS="authorinitials">ML</SPAN>, <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="ch06_06.htm"TITLE="6.6 The TZ Environment Variable "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 6.6 The TZ Environment Variable "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="ch06_08.htm"TITLE="6.8 Shell Variables "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 6.8 Shell Variables "BORDER="0"></A></TD></TR><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172">6.6 The TZ Environment Variable </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">6.8 Shell Variables </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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