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<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 8] 8.15 Differences Between Bourne and C Shell Quoting </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="1998-08-04T21:34:32Z"><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="ch08_01.htm"TITLE="8. How the Shell Interprets What You Type"><LINKREL="prev"HREF="ch08_14.htm"TITLE="8.14 Bourne Shell Quoting "><LINKREL="next"HREF="ch08_16.htm"TITLE="8.16 Quoting Handles Special Characters in Filenames "></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="ch08_14.htm"TITLE="8.14 Bourne Shell Quoting "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 8.14 Bourne Shell Quoting "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1">Chapter 8<BR>How the Shell Interprets What You Type</FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch08_16.htm"TITLE="8.16 Quoting Handles Special Characters in Filenames "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 8.16 Quoting Handles Special Characters in Filenames "BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="SECT1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-7929">8.15 Differences Between Bourne and C Shell Quoting </A></H2><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-8651"></A><ACLASS="indexterm"NAME="AUTOID-8654"></A>This article explains quoting in the C shell by comparing it to Bourne shellquoting.If you haven't read article<ACLASS="xref"HREF="ch08_14.htm"TITLE="Bourne Shell Quoting ">8.14</A>about Bourne shell quoting, please do.</P><PCLASS="para">As in the Bourne shell, the overall idea of C shell quoting is:<EMCLASS="emphasis">quoting turns off (disables) the special meaning of characters</EM>.There are three quoting characters: a single quote (<CODECLASS="literal">'</CODE>),<ACLASS="indexterm"NAME="AUTOID-8661"></A><ACLASS="indexterm"NAME="AUTOID-8664"></A>a double quote (<CODECLASS="literal">"</CODE>), and a backslash (<CODECLASS="literal">\</CODE>).</P><DIVCLASS="sect2"><H3CLASS="sect2"><ACLASS="title"NAME="UPT-ART-7929-SECT-1.1">8.15.1 Special Characters </A></H3><PCLASS="para">The C shell has several more special characters than the Bourne shell:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">! { } ~</PRE></BLOCKQUOTE></P></DIV><DIVCLASS="sect2"><H3CLASS="sect2"><ACLASS="title"NAME="UPT-ART-7929-SECT-1.2">8.15.2 How Quoting Works </A></H3><PCLASS="para"><ACLASS="xref"HREF="ch08_15.htm#UPT-ART-7929-TAB-0"TITLE="C Shell Quoting Characters">Table 8.2</A>summarizes the rules; you might want to look back at it while you read theexamples.</P><TABLECLASS="table"><CAPTIONCLASS="table"><ACLASS="title"NAME="UPT-ART-7929-TAB-0">Table 8.2: C Shell Quoting Characters</A></CAPTION><THEADCLASS="thead"><TRCLASS="row"VALIGN="TOP"><THCLASS="entry"ALIGN="LEFT"ROWSPAN="1"COLSPAN="1">Quoting Character</TH><THCLASS="entry"ALIGN="LEFT"ROWSPAN="1"COLSPAN="1">Explanation</TH></TR></THEAD><TBODYCLASS="tbody"><TRCLASS="row"VALIGN="TOP"><TDCLASS="entry"ROWSPAN="1"COLSPAN="1">'<CODECLASS="replaceable"><I>xxx</I></CODE>'</TD><TDCLASS="entry"ROWSPAN="1"COLSPAN="1"><PCLASS="para">Disable all special characters in <CODECLASS="replaceable"><I>xxx</I></CODE> except <CODECLASS="literal">!</CODE>.</P></TD></TR><TRCLASS="row"VALIGN="TOP"><TDCLASS="entry"ROWSPAN="1"COLSPAN="1">"<CODECLASS="replaceable"><I>xxx</I></CODE>"</TD><TDCLASS="entry"ROWSPAN="1"COLSPAN="1"><PCLASS="para">Disable all special characters in <CODECLASS="replaceable"><I>xxx</I></CODE> except <CODECLASS="literal">$</CODE>,`, and <CODECLASS="literal">!</CODE>.</P></TD></TR><TRCLASS="row"VALIGN="TOP"><TDCLASS="entry"ROWSPAN="1"COLSPAN="1">\<CODECLASS="replaceable"><I>x</I></CODE></TD><TDCLASS="entry"ROWSPAN="1"COLSPAN="1"><PCLASS="para">Disable special meaning of character <CODECLASS="replaceable"><I>x</I></CODE>. At end of line, a <CODECLASS="literal">\</CODE> treats the newline character like a space (continues line).</P></TD></TR></TBODY></TABLE><PCLASS="para">The major differences between C and Bourne shell quoting are:</P><ULCLASS="itemizedlist"><LICLASS="listitem"><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-8712"></A>The exclamation point (<CODECLASS="literal">!</CODE>) character can only be quoted with abackslash.That's true inside and outside single or double quotes.So, you can use<SPANCLASS="link">history substitution (<ACLASS="linkend"HREF="ch11_07.htm"TITLE="History Substitutions ">11.7</A>)</SPAN>inside quotes.For example:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>grep intelligent engineering file*.txt</B></CODE>grep: engineering: No such file or directory% <CODECLASS="userinput"><B>grep '!:1-2' !:3</B></CODE>grep 'intelligent engineering' file*.txt ...</PRE></BLOCKQUOTE></P><PCLASS="para"></P></LI><LICLASS="listitem"><PCLASS="para">In the Bourne shell, inside double quotes, a backslash (<CODECLASS="literal">\</CODE>)stops variable and command substitution (it turns off the special meaningof <CODECLASS="literal">$</CODE> and <CODECLASS="literal">`</CODE>).</P><PCLASS="para">In the C shell, you can't disable the special meaning of <CODECLASS="literal">$</CODE> or<CODECLASS="literal">`</CODE> inside double quotes.You'll need a mixture of single and double quotes.For example, searching for the string<EMCLASS="emphasis">use the `-c' switch</EM> takes some work:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>fgrep "use the \`-c' switch" *.txt</B></CODE>Unmatched \`.% <CODECLASS="userinput"><B>fgrep 'use the \`-c\' switch' *.txt</B></CODE>Unmatched '.% <CODECLASS="userinput"><B>fgrep "use the "'`-c'"' switch" *.txt</B></CODE>hints.txt:Be sure to use the `-c' switch.</PRE></BLOCKQUOTE></P><PCLASS="para">Article<ACLASS="xref"HREF="ch10_08.htm"TITLE="Fix Quoting in csh Aliases with makealias and quote ">10.8</A>shows an amazing pair of aliases that automate complicated quotingproblems like this.</P></LI><LICLASS="listitem"><PCLASS="para">In the Bourne shell, single and double quotes include newline characters.Once you open a single or double quote, you can type multiple linesbefore the closing quote.</P><PCLASS="para">In the C shell, if the quotes on a command line don't match, the shellwill print an error.<ACLASS="indexterm"NAME="AUTOID-8741"></A>To quote more than one line, type a backslash at the end of each line.Insidesingle or double quotes, the backslash-newline becomes a newline.Unquoted, backslash-newline is an argument separator:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>echo "one\</B></CODE><CODECLASS="userinput"><B>two" three\</B></CODE><CODECLASS="userinput"><B>four</B></CODE>onetwo three four</PRE></BLOCKQUOTE></P></LI></UL></DIV><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="ch08_14.htm"TITLE="8.14 Bourne Shell Quoting "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 8.14 Bourne Shell Quoting "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="ch08_16.htm"TITLE="8.16 Quoting Handles Special Characters in Filenames "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 8.16 Quoting Handles Special Characters in Filenames 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