📄 _chapter 3.htm
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<pre><span class="docEmphStrong">grep '\(3\)\.[0-9].*\1 *\1' datafile</span>
<span class="docEmphasis">northwest NW Charles Main 3.0 .98 3 34</span>
</pre>
<div align="center">
<center>
<table cellSpacing="0" width="90%" border="1" style="border-collapse: collapse" bordercolor="#111111" cellpadding="5">
<tr>
<td>
<h2 class="docSidebarTitle">EXPLANATION</h2>
<p class="docText">Prints the line if it contains a
<span class="docEmphasis">3</span> followed by a period and another number,
followed by any number of characters (<span class="docEmphasis">.*</span> ),
another <span class="docEmphasis">3</span> (originally tagged), any number
of tabs, and another <span class="docEmphasis">3.</span> Since the
<span class="docEmphasis">3</span> was enclosed in parentheses,
<span class="docEmphasis">\(3\),</span> it can be later referenced with
<span class="docEmphasis">\1.</span> <span class="docEmphasis">\1</span>
means that this was the first expression to be tagged with the
<span class="docEmphasis">\( \)</span> pair.</td>
</tr>
</table>
</center>
</div>
<h5 id="ch03list19" class="docExampleTitle">Example 3.19 </h5>
<pre><span class="docEmphStrong">grep '\<north' datafile</span>
<span class="docEmphasis">northwest NW Charles Main 3.0 .98 3 34</span>
<span class="docEmphasis">northeast NE AM Main Jr. 5.1 .94 3 13</span>
<span class="docEmphasis">north NO Margot Weber 4.5 .89 5 9</span>
</pre>
<div align="center">
<center>
<table cellSpacing="0" width="90%" border="1" style="border-collapse: collapse" bordercolor="#111111" cellpadding="5">
<tr>
<td>
<h2 class="docSidebarTitle">EXPLANATION</h2>
<p class="docText">Prints all lines containing a word starting with
<span class="docEmphasis">north.</span> The <span class="docEmphasis">\<</span>
is the beginning-of-word anchor.</td>
</tr>
</table>
</center>
</div>
<h5 id="ch03list20" class="docExampleTitle">Example 3.20 </h5>
<pre><span class="docEmphStrong">grep '\<north\>' datafile</span>
<span class="docEmphasis">north NO Margot Weber 4.5 .89 5 9</span></pre>
<div align="center">
<center>
<table cellSpacing="0" width="90%" border="1" style="border-collapse: collapse" bordercolor="#111111" cellpadding="5">
<tr>
<td>
<h2 class="docSidebarTitle">EXPLANATION</h2>
<p class="docText">Prints the line if it contains the word
<span class="docEmphasis">north.</span> The <span class="docEmphasis">\<</span>
is the beginning-of-word anchor, and the <span class="docEmphasis">\></span>
is the end-of-word anchor.</td>
</tr>
</table>
</center>
</div>
<h5 id="ch03list21" class="docExampleTitle">Example 3.21 </h5>
<pre><span class="docEmphStrong">grep '\<[a-z].*n\>' datafile</span>
<span class="docEmphasis">northwest NW Charles Main 3.0 .98 3 34</span>
<span class="docEmphasis">western WE Sharon Gray 5.3 .97 5 23</span>
<span class="docEmphasis">southern SO Suan Chin 5.1 .95 4 15</span>
<span class="docEmphasis">eastern EA TB Savage 4.4 .84 5 20</span>
<span class="docEmphasis">northeast NE AM Main Jr. 5.1 .94 3 13</span>
<span class="docEmphasis">central CT Ann Stephens 5.7 .94 5 13</span></pre>
<div align="center">
<center>
<table cellSpacing="0" width="90%" border="1" style="border-collapse: collapse" bordercolor="#111111" cellpadding="5">
<tr>
<td>
<h2 class="docSidebarTitle">EXPLANATION</h2>
<p class="docText">Prints all lines containing a word starting with a
lowercase letter, followed by any number of characters, and a word ending
in <span class="docEmphasis">n.</span> Watch the
<span class="docEmphBoldItalic">.*</span> symbol. It means any character,
including whitespace.</td>
</tr>
</table>
</center>
</div>
<h3 class="docSection1Title" id="ch03lev1sec3">3.3 <span class="docEmphasis">grep</span> with
Pipes</h3>
<p class="docText">Instead of taking its input from a file,
<span class="docEmphasis">grep</span> often gets its input from a pipe.</p>
<h5 id="ch03list22" class="docExampleTitle">Example 3.22 </h5>
<pre>% <span class="docEmphStrong">ls -l</span>
<span class="docEmphasis">drwxrwxrwx 2 ellie 2441 Jan 6 12:34 dir1</span>
<span class="docEmphasis">-rw-r--r-- 1 ellie 1538 Jan 2 15:50 file1</span>
<span class="docEmphasis">-rw-r--r-- 1 ellie 1539 Jan 3 13:36 file2</span>
<span class="docEmphasis">drwxrwxrwx 2 ellie 2341 Jan 6 12:34 grades</span>
% <span class="docEmphStrong">ls -l | grep '^d'</span>
<span class="docEmphasis">drwxrwxrwx 2 ellie 2441 Jan 6 12:34 dir1</span>
<span class="docEmphasis">drwxrwxrwx 2 ellie 2341 Jan 6 12:34 grades</span></pre>
<table cellSpacing="0" width="90%" border="1" align="center">
<tr>
<td>
<h2 class="docSidebarTitle">EXPLANATION</h2>
<p class="docText">The output of the <span class="docEmphasis">ls</span>
command is piped to <span class="docEmphasis">grep.</span> All lines of
output that begin with a <span class="docEmphasis">d</span> are printed;
that is, all directories are printed.</td>
</tr>
</table>
<h3 class="docSection1Title" id="ch03lev1sec4">3.4 <span class="docEmphasis">grep</span> with
Options</h3>
<p class="docText">The <span class="docEmphasis">grep</span> command has a
number of options that control its behavior. Not all versions of UNIX support
exactly the same options, so be sure to check your man pages for a complete
list.</p>
<pre>% <span class="docEmphStrong">cat datafile</span>
<span class="docEmphasis">northwest NW Charles Main 3.0 .98 3 34</span>
<span class="docEmphasis">western WE Sharon Gray 53 .97 5 23</span>
<span class="docEmphasis">southwest SW Lewis Dalsass 2.7 .8 2 18</span>
<span class="docEmphasis">southern SO Suan Chin 5.1 .95 4 15</span>
<span class="docEmphasis">southeast SE Patricia Hemenway 4.0 .7 4 17</span>
<span class="docEmphasis">eastern EA TB Savage 4.4 .84 5 20</span>
<span class="docEmphasis">northeast NE AM Main Jr. 5.1 .94 3 13</span>
<span class="docEmphasis">north NO Margot Weber 4.5 .89 5 9</span>
<span class="docEmphasis">central CT Ann Stephens 5.7 .94 5 13</span>
</pre>
<h5 id="ch03list23" class="docExampleTitle">Example 3.23 </h5>
<pre><span class="docEmphStrong">grep 杗 '^south' datafile</span>
<span class="docEmphasis">3:southwest SW Lewis Dalsass 2.7 .8 2 18</span>
<span class="docEmphasis">4:southern SO Suan Chin 5.1 .95 4 15</span>
<span class="docEmphasis">5:southeast SE Patricia Hemenway 4.0 .7 4 17</span>
</pre>
<div align="center">
<center>
<table cellSpacing="0" width="90%" border="1" style="border-collapse: collapse" bordercolor="#111111" cellpadding="5">
<tr>
<td>
<h2 class="docSidebarTitle">EXPLANATION</h2>
<p class="docText">The <span class="docEmphasis">杗</span> option precedes
each line with the number of the line where the pattern was found, followed
by the line.</td>
</tr>
</table>
</center>
</div>
<h5 id="ch03list24" class="docExampleTitle">Example 3.24 </h5>
<pre><span class="docEmphStrong">grep 杋 'pat' datafile</span>
<span class="docEmphasis">southeast SE Patricia Hemenway 4.0 .7 4 17</span>
</pre>
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<center>
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<td>
<h2 class="docSidebarTitle">EXPLANATION</h2>
<p class="docText">The <span class="docEmphasis">杋</span> option turns off
case sensitivity. It does not matter if the expression
<span class="docEmphasis">pat</span> contains any combination of upper- or
lowercase letters.</td>
</tr>
</table>
</center>
</div>
<h5 id="ch03list25" class="docExampleTitle">Example 3.25 </h5>
<pre><span class="docEmphStrong">grep 杤 'Suan Chin' datafile</span>
<span class="docEmphasis">northwest NW Charles Main 3.0 .98 3 34</span>
<span class="docEmphasis">western WE Sharon Gray 5.3 .97 5 23</span>
<span class="docEmphasis">southwest SW Lewis Dalsass 2.7 .8 2 18</span>
<span class="docEmphasis">southeast SE Patricia Hemenway 4.0 .7 4 17</span>
<span class="docEmphasis">eastern EA TB Savage 4.4 .84 5 20</span>
<span class="docEmphasis">northeast NE AM Main Jr. 5.1 .94 3 13</span>
<span class="docEmphasis">north NO Margot Weber 4.5 .89 5 9</span>
<span class="docEmphasis">central CT Ann Stephens 5.7 .94 5 13</span>
</pre>
<div align="center">
<center>
<table cellSpacing="0" width="90%" border="1" style="border-collapse: collapse" bordercolor="#111111" cellpadding="5">
<tr>
<td>
<h2 class="docSidebarTitle">EXPLANATION</h2>
<p class="docText">Here, the <span class="docEmphasis">杤</span> option
prints all lines <span class="docEmphasis">not</span> containing the pattern
<span class="docEmphasis">Suan Chin.</span> This option is used when
deleting a specific entry from the input file. To really remove the entry,
you would redirect the output of <span class="docEmphasis">grep</span> to a
temporary file, and then change the name of the temporary file back to the
name of the original file as shown here:</p>
<pre>grep -v 'Suan Chin' datafile > temp
mv temp datafile
</pre>
<p class="docText">Remember that you must use a temporary file when
redirecting the output from <span class="docEmphasis">datafile.</span> If
you redirect from <span class="docEmphasis">datafile</span> to
<span class="docEmphasis">datafile,</span> the shell will "clobber" the
<span class="docEmphasis">datafile.</span> (See "Redirection" on page 16.)</td>
</tr>
</table>
</center>
</div>
<pre>% <span class="docEmphStrong">cat datafile</span>
<span class="docEmphasis">northwest NW Charles Main 3.0 .98 3 34</span>
<span class="docEmphasis">western WE Sharon Gray 53 .97 5 23</span>
<span class="docEmphasis">southwest SW Lewis Dalsass 2.7 .8 2 18</span>
<span class="docEmphasis">southern SO Suan Chin 5.1 .95 4 15</span>
<span class="docEmphasis">southeast SE Patricia Hemenway 4.0 .7 4 17</span>
<span class="docEmphasis">eastern EA TB Savage 4.4 .84 5 20</span>
<span class="docEmphasis">northeast NE AM Main Jr. 5.1 .94 3 13</span>
<span class="docEmphasis">north NO Margot Weber 4.5 .89 5 9</span>
<span class="docEmphasis">central CT Ann Stephens 5.7 .94 5 13</span>
</pre>
<h5 id="ch03list26" class="docExampleTitle">Example 3.26 </h5>
<pre><span class="docEmphStrong">grep 杔 'SE' *</span>
<span class="docEmphasis">datafile</span>
<span class="docEmphasis">datebook</span>
</pre>
<div align="center">
<center>
<table cellSpacing="0" width="90%" border="1" style="border-collapse: collapse" bordercolor="#111111" cellpadding="5">
<tr>
<td>
<h2 class="docSidebarTitle">EXPLANATION</h2>
<p class="docText">The <span class="docEmphasis">杔</span> option causes
<span class="docEmphasis">grep</span> to print out only the filenames where
the pattern is found instead of the line of text</td>
</tr>
</table>
</center>
</div>
<h5 id="ch03list27" class="docExampleTitle">Example 3.27 </h5>
<pre><span class="docEmphStrong">grep 朿 'west' datafile</span>
<span class="docEmphasis">3</span>
</pre>
<div align="center">
<center>
<table cellSpacing="0" width="90%" border="1" style="border-collapse: collapse" bordercolor="#111111" cellpadding="5">
<tr>
<td>
<h2 class="docSidebarTitle">EXPLANATION</h2>
<p class="docText">The ⌨️ 快捷键说明
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