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<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 3] 3.6 Stop Accidental Bourne Shell Logouts </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="1998-08-04T21:32:34Z"><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="ch03_01.htm"TITLE="3. Logging Out"><LINKREL="prev"HREF="ch03_05.htm"TITLE="3.5 Stop Accidental C Shell Logouts "><LINKREL="next"HREF="ch03_07.htm"TITLE="3.7 Detaching a Session with screen "></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="ch03_05.htm"TITLE="3.5 Stop Accidental C Shell Logouts "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 3.5 Stop Accidental C Shell Logouts "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1">Chapter 3<BR>Logging Out</FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch03_07.htm"TITLE="3.7 Detaching a Session with screen "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 3.7 Detaching a Session with screen "BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="SECT1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-0222">3.6 Stop Accidental Bourne Shell Logouts </A></H2><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-4187"></A>It's pretty easy to type one too many CTRL-d characters and log out of aBourne shell without meaning to.The C shell has an<SPANCLASS="link"><EMCLASS="emphasis">ignoreeof</EM> shell variable (<ACLASS="linkend"HREF="ch03_05.htm"TITLE="Stop Accidental C Shell Logouts ">3.5</A>)</SPAN>that won't let you log out with CTRL-d.So do the Korn shell and <EMCLASS="emphasis">bash</EM>; use <CODECLASS="literal">set -o ignoreeof</CODE>.</P><PCLASS="para">Here's a different sort of solution for the Bourne shell.When you end the shell, it asks if you're sure.If you don't answer yes, a new shell is started to replace your old one.</P><PCLASS="para">First, make<SPANCLASS="link"> a file like the C shell's <EMCLASS="emphasis">.logout</EM> that will be read whenyour Bourne shell exits . (<ACLASS="linkend"HREF="ch03_02.htm"TITLE="Running Commands at Bourne/Korn Shell Logout ">3.2</A>)</SPAN>Save your<SPANCLASS="link">tty (<ACLASS="linkend"HREF="ch03_08.htm"TITLE="What tty Am I On? ">3.8</A>)</SPAN>name in an<SPANCLASS="link">environment variable (<ACLASS="linkend"HREF="ch06_01.htm#UPT-ART-1170"TITLE="What Environment Variables Are Good For ">6.1</A>)</SPAN>,too-you'll need it later:</P><PCLASS="para"><TABLECLASS="screen.co"BORDER="1"><TR><THVALIGN="TOP"><PRECLASS="calloutlist"> <ACLASS="co"HREF="ch44_12.htm"TITLE="44.12 Trapping Exits Caused by Interrupts ">trap</A> </PRE></TH><TDVALIGN="TOP"><PRECLASS="screen">TTY=`tty`; export TTYtrap '. $HOME/.sh_logout; exit' 0 </PRE></TD></TR></TABLE></P><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-4205"></A>(Your system may need <CODECLASS="literal">$LOGDIR</CODE> instead of <CODECLASS="literal">$HOME</CODE>.)Put the following lines in your new <EMCLASS="emphasis">.sh_logout</EM> file:</P><PCLASS="para"><TABLECLASS="screen.co"BORDER="1"><TR><THVALIGN="TOP"><PRECLASS="calloutlist"><ACLASS="co"HREF="ch45_20.htm"TITLE="45.20 Overview: Open Files and File Descriptors ">exec <</A> <ACLASS="co"HREF="ch44_06.htm"TITLE="44.6 Pattern Matching in case Statements ">case</A> <ACLASS="co"HREF="ch38_02.htm"TITLE="38.2 fork and exec ">exec</A> <ACLASS="co"HREF="ch51_09.htm"TITLE='51.9 Making a "Login" Shell'>-sh</A> </PRE></TH><TDVALIGN="TOP"><PRECLASS="screen">exec < $TTYecho "Do you really want to log out? \c"read anscase "$ans" in[Yy]*) ;;*) exec $HOME/bin/-sh ;;esac</PRE></TD></TR></TABLE></P><PCLASS="para">The last line is some trickery to start a new<SPANCLASS="link">login shell (<ACLASS="linkend"HREF="ch51_09.htm"TITLE='Making a "Login" Shell'>51.9</A>)</SPAN>.The shell<SPANCLASS="link">closes your tty (<ACLASS="linkend"HREF="ch45_20.htm"TITLE="Overview: Open Files and File Descriptors ">45.20</A>)</SPAN>before reading your <EMCLASS="emphasis">.sh_logout</EM> file;the <CODECLASS="literal">exec < $TTY</CODE> reconnects the shell's standard input to yourterminal.</P><PCLASS="para">Note that if your system is <EMCLASS="emphasis">very</EM> slow, you may not get the remindermessage for a couple of seconds-you might forget that it's coming andwalk away.That hasn't been a problem where I've tested this.If it is for you though, replace the <CODECLASS="literal">read</CODE> <CODECLASS="literal">ans</CODE> with a programlike<SPANCLASS="link"><EMCLASS="emphasis">grabchars</EM> (<ACLASS="linkend"HREF="ch45_32.htm"TITLE="A Better read Command: grabchars ">45.32</A>)</SPAN>that times out and gives a default answer after a while.There may be some Bourne shells that need other tricks-and others that don'tneed these tricks-but this should give you an idea of what to do.</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="ch03_05.htm"TITLE="3.5 Stop Accidental C Shell Logouts "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 3.5 Stop Accidental C Shell Logouts "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="ch03_07.htm"TITLE="3.7 Detaching a Session with screen "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 3.7 Detaching a Session with screen "BORDER="0"></A></TD></TR><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172">3.5 Stop Accidental C Shell Logouts </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">3.7 Detaching a Session with screen </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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