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Changes to doc/grep_13.html
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From: |
Karl Berry |
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Subject: |
Changes to doc/grep_13.html |
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Date: |
Sun, 24 May 2009 18:43:13 +0000 |
CVSROOT: /web/grep
Module name: grep
Changes by: Karl Berry <karl> 09/05/24 18:43:01
Index: doc/grep_13.html
===================================================================
RCS file: doc/grep_13.html
diff -N doc/grep_13.html
--- doc/grep_13.html 23 Jan 2002 10:33:52 -0000 1.3
+++ /dev/null 1 Jan 1970 00:00:00 -0000
@@ -1,300 +0,0 @@
-<HTML>
-<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
-<!-- Created on January, 23 2002 by texi2html 1.64 -->
-<!--
-Written by: Lionel Cons <address@hidden> (original author)
- Karl Berry <address@hidden>
- Olaf Bachmann <address@hidden>
- and many others.
-Maintained by: Olaf Bachmann <address@hidden>
-Send bugs and suggestions to <address@hidden>
-
--->
-<HEAD>
-<TITLE>grep, print lines matching a pattern: Usage</TITLE>
-
-<META NAME="description" CONTENT="grep, print lines matching a pattern: Usage">
-<META NAME="keywords" CONTENT="grep, print lines matching a pattern: Usage">
-<META NAME="resource-type" CONTENT="document">
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-<META NAME="Generator" CONTENT="texi2html 1.64">
-
-</HEAD>
-
-<BODY LANG="" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#800080"
ALINK="#FF0000">
-
-<A NAME="SEC13"></A>
-<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
-<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="grep_12.html#SEC12"> <
</A>]</TD>
-<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="grep_14.html#SEC14"> > </A>]</TD>
-<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A
HREF="grep_14.html#SEC14"> << </A>]</TD>
-<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="grep.html#SEC_Top"> Up </A>]</TD>
-<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="grep_14.html#SEC14"> >>
</A>]</TD>
-<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE"
ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A
HREF="grep.html#SEC_Top">Top</A>]</TD>
-<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A
HREF="grep_toc.html#SEC_Contents">Contents</A>]</TD>
-<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="grep_21.html#SEC21">Index</A>]</TD>
-<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="grep_abt.html#SEC_About"> ?
</A>]</TD>
-</TR></TABLE>
-<HR SIZE=1>
-<H1> 6. Usage </H1>
-<!--docid::SEC13::-->
-<P>
-
-<A NAME="IDX209"></A>
-Here is an example shell command that invokes GNU <CODE>grep</CODE>:
-</P><P>
-
-<TABLE><tr><td> </td><td class=example><pre>grep -i 'hello.*world' menu.h
main.c
-</pre></td></tr></table></P><P>
-
-This lists all lines in the files <TT>`menu.h'</TT> and <TT>`main.c'</TT> that
-contain the string <SAMP>`hello'</SAMP> followed by the string
<SAMP>`world'</SAMP>;
-this is because <SAMP>`.*'</SAMP> matches zero or more characters within a
line.
-See section <A HREF="grep_7.html#SEC7">5. Regular Expressions</A>. The
<SAMP>`-i'</SAMP> option causes <CODE>grep</CODE>
-to ignore case, causing it to match the line <SAMP>`Hello, world!'</SAMP>,
which
-it would not otherwise match. See section <A HREF="grep_2.html#SEC2">2.
Invoking <CODE>grep</CODE></A>, for more details about
-how to invoke <CODE>grep</CODE>.
-</P><P>
-
-<A NAME="IDX210"></A>
-<A NAME="IDX211"></A>
-Here are some common questions and answers about <CODE>grep</CODE> usage.
-</P><P>
-
-<OL>
-
-<LI>
-How can I list just the names of matching files?
-<P>
-
-<TABLE><tr><td> </td><td class=example><pre>grep -l 'main' *.c
-</pre></td></tr></table></P><P>
-
-lists the names of all C files in the current directory whose contents
-mention <SAMP>`main'</SAMP>.
-</P><P>
-
-<LI>
-How do I search directories recursively?
-<P>
-
-<TABLE><tr><td> </td><td class=example><pre>grep -r 'hello' /home/gigi
-</pre></td></tr></table></P><P>
-
-searches for <SAMP>`hello'</SAMP> in all files under the directory
-<TT>`/home/gigi'</TT>. For more control of which files are searched, use
-<CODE>find</CODE>, <CODE>grep</CODE> and <CODE>xargs</CODE>. For example,
-the following command searches only C files:
-</P><P>
-
-<TABLE><tr><td> </td><td class=smallexample><FONT SIZE=-1><pre>find
/home/gigi -name '*.c' -print | xargs grep 'hello' /dev/null
-</FONT></pre></td></tr></table></P><P>
-
-This differs from the command:
-</P><P>
-
-<TABLE><tr><td> </td><td class=example><pre>grep -r 'hello' *.c
-</pre></td></tr></table></P><P>
-
-which merely looks for <SAMP>`hello'</SAMP> in all files in the current
-directory whose names end in <SAMP>`.c'</SAMP>. Here the <SAMP>`-r'</SAMP> is
-probably unnecessary, as recursion occurs only in the unlikely event
-that one of <SAMP>`.c'</SAMP> files is a directory.
-</P><P>
-
-<LI>
-What if a pattern has a leading <SAMP>`-'</SAMP>?
-<P>
-
-<TABLE><tr><td> </td><td class=example><pre>grep -e '--cut here--' *
-</pre></td></tr></table></P><P>
-
-searches for all lines matching <SAMP>`--cut here--'</SAMP>. Without
<SAMP>`-e'</SAMP>,
-<CODE>grep</CODE> would attempt to parse <SAMP>`--cut here--'</SAMP> as a list
of
-options.
-</P><P>
-
-<LI>
-Suppose I want to search for a whole word, not a part of a word?
-<P>
-
-<TABLE><tr><td> </td><td class=example><pre>grep -w 'hello' *
-</pre></td></tr></table></P><P>
-
-searches only for instances of <SAMP>`hello'</SAMP> that are entire words; it
-does not match <SAMP>`Othello'</SAMP>. For more control, use
<SAMP>`\<'</SAMP> and
-<SAMP>`\>'</SAMP> to match the start and end of words. For example:
-</P><P>
-
-<TABLE><tr><td> </td><td class=example><pre>grep 'hello\>' *
-</pre></td></tr></table></P><P>
-
-searches only for words ending in <SAMP>`hello'</SAMP>, so it matches the word
-<SAMP>`Othello'</SAMP>.
-</P><P>
-
-<LI>
-How do I output context around the matching lines?
-<P>
-
-<TABLE><tr><td> </td><td class=example><pre>grep -C 2 'hello' *
-</pre></td></tr></table></P><P>
-
-prints two lines of context around each matching line.
-</P><P>
-
-<LI>
-How do I force grep to print the name of the file?
-<P>
-
-Append <TT>`/dev/null'</TT>:
-</P><P>
-
-<TABLE><tr><td> </td><td class=example><pre>grep 'eli' /etc/passwd
/dev/null
-</pre></td></tr></table></P><P>
-
-gets you:
-</P><P>
-
-<TABLE><tr><td> </td><td class=smallexample><FONT
SIZE=-1><pre>/etc/passwd:eli:DNGUTF58.IMe.:98:11:Eli
Smith:/home/do/eli:/bin/bash
-</FONT></pre></td></tr></table></P><P>
-
-<LI>
-Why do people use strange regular expressions on <CODE>ps</CODE> output?
-<P>
-
-<TABLE><tr><td> </td><td class=example><pre>ps -ef | grep '[c]ron'
-</pre></td></tr></table></P><P>
-
-If the pattern had been written without the square brackets, it would
-have matched not only the <CODE>ps</CODE> output line for <CODE>cron</CODE>,
-but also the <CODE>ps</CODE> output line for <CODE>grep</CODE>.
-Note that some platforms <CODE>ps</CODE> limit the ouput to the width
-of the screen, grep does not have any limit on the length of a line
-except the available memory.
-</P><P>
-
-<LI>
-Why does <CODE>grep</CODE> report "Binary file matches"?
-<P>
-
-If <CODE>grep</CODE> listed all matching "lines" from a binary file, it
-would probably generate output that is not useful, and it might even
-muck up your display. So GNU <CODE>grep</CODE> suppresses output from
-files that appear to be binary files. To force GNU <CODE>grep</CODE>
-to output lines even from files that appear to be binary, use the
-<SAMP>`-a'</SAMP> or <SAMP>`--binary-files=text'</SAMP> option. To eliminate
the
-"Binary file matches" messages, use the <SAMP>`-I'</SAMP> or
-<SAMP>`--binary-files=without-match'</SAMP> option.
-</P><P>
-
-<LI>
-Why doesn't <SAMP>`grep -lv'</SAMP> print nonmatching file names?
-<P>
-
-<SAMP>`grep -lv'</SAMP> lists the names of all files containing one or more
-lines that do not match. To list the names of all files that contain no
-matching lines, use the <SAMP>`-L'</SAMP> or
<SAMP>`--files-without-match'</SAMP>
-option.
-</P><P>
-
-<LI>
-I can do OR with <SAMP>`|'</SAMP>, but what about AND?
-<P>
-
-<TABLE><tr><td> </td><td class=example><pre>grep 'paul' /etc/motd | grep
'franc,ois'
-</pre></td></tr></table></P><P>
-
-finds all lines that contain both <SAMP>`paul'</SAMP> and
<SAMP>`franc,ois'</SAMP>.
-</P><P>
-
-<LI>
-How can I search in both standard input and in files?
-<P>
-
-Use the special file name <SAMP>`-'</SAMP>:
-</P><P>
-
-<TABLE><tr><td> </td><td class=example><pre>cat /etc/passwd | grep
'alain' - /etc/motd
-</pre></td></tr></table></P><P>
-
-<LI>
-<A NAME="IDX212"></A>
-How to express palindromes in a regular expression?
-<P>
-
-It can be done by using the back referecences, for example a palindrome
-of 4 chararcters can be written in BRE.
-</P><P>
-
-<TABLE><tr><td> </td><td class=example><pre>grep -w -e '\(.\)\(.\).\2\1'
file
-</pre></td></tr></table></P><P>
-
-It matches the word "radar" or "civic".
-</P><P>
-
-Guglielmo Bondioni proposed a single RE that finds all the palindromes up to 19
-characters long.
-</P><P>
-
-<TABLE><tr><td> </td><td class=example><pre>egrep -e
'^(.?)(.?)(.?)(.?)(.?)(.?)(.?)(.?)(.?).?\9\8\7\6\5\4\3\2\1$' file
-</pre></td></tr></table></P><P>
-
-Note this is done by using GNU ERE extensions, it might not be portable on
-other greps.
-</P><P>
-
-<LI>
-Why are my expressions whith the vertical bar fail?
-<P>
-
-<TABLE><tr><td> </td><td class=example><pre>/bin/echo "ba" | egrep
'(a)\1|(b)\1'
-</pre></td></tr></table></P><P>
-
-The first alternate branch fails then the first group was not in the match
-this will make the second alternate branch fails. For example, "aaba" will
-match, the first group participate in the match and can be reuse in the
-second branch.
-</P><P>
-
-<LI>
-What do <CODE>grep, fgrep, egrep</CODE> stand for ?
-<P>
-
-grep comes from the way line editing was done on Unix. For example,
-<CODE>ed</CODE> uses this syntax to print a list of matching lines on the
screen.
-</P><P>
-
-<TABLE><tr><td> </td><td class=example><pre>global/regular
expression/print
-g/re/p
-</pre></td></tr></table></P><P>
-
-<CODE>fgrep</CODE> stands for Fixed <CODE>grep</CODE>, <CODE>egrep</CODE>
Extended
-<CODE>grep</CODE>.
-</P><P>
-
-</OL>
-<P>
-
-<A NAME="Reporting Bugs"></A>
-<HR SIZE=1>
-<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
-<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="grep_12.html#SEC12"> <
</A>]</TD>
-<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="grep_14.html#SEC14"> > </A>]</TD>
-<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A
HREF="grep_14.html#SEC14"> << </A>]</TD>
-<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="grep.html#SEC_Top"> Up </A>]</TD>
-<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="grep_14.html#SEC14"> >>
</A>]</TD>
-<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE"
ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A
HREF="grep.html#SEC_Top">Top</A>]</TD>
-<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A
HREF="grep_toc.html#SEC_Contents">Contents</A>]</TD>
-<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="grep_21.html#SEC21">Index</A>]</TD>
-<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="grep_abt.html#SEC_About"> ?
</A>]</TD>
-</TR></TABLE>
-<BR>
-<FONT SIZE="-1">
-This document was generated
-by <I>root</I> on <I>January, 23 2002</I>
-using <A HREF="http://www.mathematik.uni-kl.de/~obachman/Texi2html
-"><I>texi2html</I></A>
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