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<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 9] 9.23 Workaround for "Arguments too long" Error</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="1998-08-04T21:35:30Z"><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="ch09_01.htm"TITLE="9. Saving Time on the Command Line"><LINKREL="prev"HREF="ch09_22.htm"TITLE="9.22 xargs: Problems with Spaces and Newlines "><LINKREL="next"HREF="ch09_24.htm"TITLE="9.24 Get File List by Editing Output of ls -l, grep, etc. "></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="ch09_22.htm"TITLE="9.22 xargs: Problems with Spaces and Newlines "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 9.22 xargs: Problems with Spaces and Newlines "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1">Chapter 9<BR>Saving Time on the Command Line</FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch09_24.htm"TITLE="9.24 Get File List by Editing Output of ls -l, grep, etc. "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 9.24 Get File List by Editing Output of ls -l, grep, etc. "BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="SECT1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-0485">9.23 Workaround for "Arguments too long" Error</A></H2><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-11215"></A><ACLASS="indexterm"NAME="AUTOID-11217"></A>When the shell matches a<SPANCLASS="link">wildcard (<ACLASS="linkend"HREF="ch15_01.htm#UPT-ART-1480"TITLE="File Naming Wildcards ">15.1</A>)</SPAN>in a big directory or with long<SPANCLASS="link">pathnames (<ACLASS="linkend"HREF="ch14_02.htm"TITLE="Using Relative and Absolute Pathnames ">14.2</A>, <ACLASS="linkend"HREF="ch15_06.htm"TITLE="Maybe You Shouldn't Use Wildcards in Pathnames ">15.6</A>)</SPAN>,it can sometimes run out of room.You'll get an error like this:</P><PCLASS="para"><TABLECLASS="screen.co"BORDER="1"><TR><THVALIGN="TOP"><PRECLASS="calloutlist"><ACLASS="co"HREF="ch43_07.htm"TITLE="43.7 Quick-and-Dirty Formatting Before Printing ">pr</A> </PRE></TH><TDVALIGN="TOP"><PRECLASS="screen">% <CODECLASS="userinput"><B>pr */* | lpr</B></CODE>Arguments too long.</PRE></TD></TR></TABLE></P><PCLASS="para">Sometimes you can work around that.The trick is to split the command line into pieces with<SPANCLASS="link">semicolons (<ACLASS="linkend"HREF="ch08_05.htm"TITLE="Command-Line Evaluation ">8.5</A>)</SPAN>-and use a<SPANCLASS="link">subshell (<ACLASS="linkend"HREF="ch13_07.htm"TITLE="The () Subshell Operators ">13.7</A>)</SPAN>to combine the outputs.For example, I rewrote the previous command like this:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>(pr [a-f]*/*;pr [g-m]*/*;pr [n-z]*/*) | lpr</B></CODE></PRE></BLOCKQUOTE></P><PCLASS="para">The first command prints the files in directories whose names start with"a" through "f," and so on.</P><PCLASS="para">How did I decide where to split?There's no magic formula.The number of pieces you'll need and the way you divide them will dependon how many directories and files you're trying to match - and yourversion of UNIX.Do it by experiment.A dummy command like <EMCLASS="emphasis">true</EM> that ignores its arguments is good for this.In the example above, I first tried splitting the arguments in half.Then I split them more.I did the same for other chunks until the shell was happy with all of them:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>true [a-m]*/*</B></CODE> Arguments too long.% <CODECLASS="userinput"><B>true [a-f]*/*</B></CODE> % <CODECLASS="userinput"><B>true [g-z]*/*</B></CODE> Arguments too long.% <CODECLASS="userinput"><B>true [g-m]*/*</B></CODE> % <CODECLASS="userinput"><B>true [n-z]*/*</B></CODE></PRE></BLOCKQUOTE></P><PCLASS="para">This trick works fine for commands like <EMCLASS="emphasis">pr</EM> that make regular outputthat is consistent whether you run separate chunks of files or do allat the same time.Some commands start each listing with a separate heading - for instance,<EMCLASS="emphasis">ls -l</EM> prints <CODECLASS="literal">total</CODE> <CODECLASS="replaceable"><I>n</I></CODE> before it lists a directory.That kind of command won't work as neatly with this trick because you'llget several headings mixed in with the output instead of just one.Still, it might be better than nothing!</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="ch09_22.htm"TITLE="9.22 xargs: Problems with Spaces and Newlines "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 9.22 xargs: Problems with Spaces and Newlines "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="ch09_24.htm"TITLE="9.24 Get File List by Editing Output of ls -l, grep, etc. "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 9.24 Get File List by Editing Output of ls -l, grep, etc. "BORDER="0"></A></TD></TR><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172">9.22 xargs: Problems with Spaces and Newlines </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">9.24 Get File List by Editing Output of ls -l, grep, etc. </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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