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<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 44] 44.11 Set Exit Status of a Shell (Script) </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="1998-08-04T21:53:44Z"><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="ch44_01.htm"TITLE="44. Shell Programming for the Uninitiated"><LINKREL="prev"HREF="ch44_10.htm"TITLE="44.10 Loops That Test Exit Status "><LINKREL="next"HREF="ch44_12.htm"TITLE="44.12 Trapping Exits Caused by Interrupts "></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="ch44_10.htm"TITLE="44.10 Loops That Test Exit Status "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 44.10 Loops That Test Exit Status "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1">Chapter 44<BR>Shell Programming for the Uninitiated</FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch44_12.htm"TITLE="44.12 Trapping Exits Caused by Interrupts "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 44.12 Trapping Exits Caused by Interrupts "BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="SECT1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-7110">44.11 Set Exit Status of a Shell (Script) </A></H2><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-50946"></A>Most standard UNIX commands return a<SPANCLASS="link">status (<ACLASS="linkend"HREF="ch44_07.htm"TITLE="Exit Status of UNIX Processes ">44.7</A>)</SPAN>.Your shell script should, too.This section shows how to set the right exit status for both normal exits and error exits.</P><PCLASS="para">To end a shell script and set its exit status, use the <EMCLASS="emphasis">exit</EM> command.Give <EMCLASS="emphasis">exit</EM> the exit status that your script should have.If it has no explicit status, it will exit with the status of the lastcommand run.</P><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-50953"></A>Here's an example: a rewrite of the <EMCLASS="emphasis">bkedit</EM> script from article<ACLASS="xref"HREF="ch44_08.htm"TITLE="Test Exit Status with the if Statement ">44.8</A>.If the script can make a backup copy, the editor is run and the scriptreturnsthe exit status from <EMCLASS="emphasis">vi</EM> (usually 0).If something goes wrong with the copy, the script prints an error and returnsan exit status of 1.Here's the script:</P><PCLASS="para"><TABLECLASS="screen.co"BORDER="1"><TR><THVALIGN="TOP"><PRECLASS="calloutlist"> <ACLASS="co"HREF="ch08_06.htm"TITLE="8.6 Output Command-Line Arguments ">1>&2</A> </PRE></TH><TDVALIGN="TOP"><PRECLASS="screen"><ACLASS="indexterm"NAME="AUTOID-50962"></A><ACLASS="indexterm"NAME="AUTOID-50965"></A><ACLASS="indexterm"NAME="AUTOID-50968"></A><ACLASS="indexterm"NAME="AUTOID-50971"></A>#!/bin/shif cp "$1" "$1.bak"then vi "$1" exit # USE STATUS FROM vielse echo "bkedit quitting: can't make backup?" 1>&2 exit 1fi</PRE></TD></TR></TABLE></P><PCLASS="para">Here's what happens if I run it without a filename:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">$ <CODECLASS="userinput"><B>bkedit</B></CODE>cp: usage: cp fn1 fn2 or cp fn1 [fn2...] dirbkedit quitting: can't make backup?</PRE></BLOCKQUOTE></P><PCLASS="para"> And here's what's left in the exit status variable:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">$ <CODECLASS="userinput"><B>echo $?</B></CODE>1</PRE></BLOCKQUOTE></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="ch44_10.htm"TITLE="44.10 Loops That Test Exit Status "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 44.10 Loops That Test Exit Status "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="ch44_12.htm"TITLE="44.12 Trapping Exits Caused by Interrupts "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 44.12 Trapping Exits Caused by Interrupts "BORDER="0"></A></TD></TR><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172">44.10 Loops That Test Exit Status </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">44.12 Trapping Exits Caused by Interrupts </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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