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<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 6] 6.10 Running a Command with a Temporarily Different Environment </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="1998-10-23T15:38:12Z"><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_09.htm"TITLE="6.9 Special C Shell Variables "><LINKREL="next"HREF="ch07_01.htm"TITLE="7. Setting Your Shell Prompt"></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_09.htm"TITLE="6.9 Special C Shell Variables "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 6.9 Special C Shell Variables "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="CHAPTER"HREF="ch07_01.htm"TITLE="7. Setting Your Shell Prompt"><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 7. Setting Your Shell Prompt"BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="SECT1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-5850">6.10 Running a Command with a Temporarily Different Environment </A></H2><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-6531"></A><ACLASS="indexterm"NAME="AUTOID-6534"></A>Quite a few UNIX commands set themselves up by reading the environment.For example, the <EMCLASS="emphasis">vi</EM> editor reads startup commands from the <EMCLASS="emphasis">EXINIT</EM>environment variable.Sometimes, you'll want to override the setting of an environmentvariable for just one command.There's an easier way than setting the variable to a different value andchanging it back after you run the command:</P><ULCLASS="itemizedlist"><LICLASS="listitem"><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-6541"></A><ACLASS="indexterm"NAME="AUTOID-6544"></A>In the Bourne shell, type:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">$ <CODECLASS="userinput"><B>VARNAME=value command args</B></CODE></PRE></BLOCKQUOTE></P><PCLASS="para"></P></LI><LICLASS="listitem"><PCLASS="para">In the C shell on UNIX systems that have the <EMCLASS="emphasis">env</EM> command, type:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>env VARNAME=value command args</B></CODE></PRE></BLOCKQUOTE></P><PCLASS="para"></P></LI><LICLASS="listitem"><PCLASS="para">Or, in any C shell, use a<SPANCLASS="link">subshell (<ACLASS="linkend"HREF="ch13_07.htm"TITLE="The () Subshell Operators ">13.7</A>)</SPAN>like this:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>(setenv VARNAME value; command args)</B></CODE></PRE></BLOCKQUOTE></P></LI></UL><PCLASS="para">For example, if your <EMCLASS="emphasis">EXINIT</EM> variable has:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">set wrapscan showmatch number</PRE></BLOCKQUOTE></P><PCLASS="para">and you want to add <CODECLASS="literal">nowrapscan</CODE> to the endof it just this once, you could type (to the Bourne shell):</P><PCLASS="para"><TABLECLASS="screen.co"BORDER="1"><TR><THVALIGN="TOP"><PRECLASS="calloutlist"><ACLASS="co"HREF="ch06_01.htm"TITLE="6.1 What Environment Variables Are Good For ">$</A> </PRE></TH><TDVALIGN="TOP"><PRECLASS="screen">$ <CODECLASS="userinput"><B>EXINIT="$EXINIT nowrapscan" vi afile</B></CODE></PRE></TD></TR></TABLE></P><PCLASS="para">After that <EMCLASS="emphasis">vi</EM> command ran, <EMCLASS="emphasis">EXINIT</EM> wouldn't contain<CODECLASS="literal">nowrapscan</CODE>.</P><PCLASS="para">For a great example of this technique, see article<ACLASS="xref"HREF="ch06_07.htm"TITLE="What Time Is It in Japan? ">6.7</A>.</P><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="ch06_09.htm"TITLE="6.9 Special C Shell Variables "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 6.9 Special C Shell Variables "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="CHAPTER"HREF="ch07_01.htm"TITLE="7. Setting Your Shell Prompt"><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 7. 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