blocks|key|732940|text|你可以使用|type|unstyled|depth|inlineStyleRanges|entityRanges|data|732941|awk+'/test_pattern/+{
++++match($0,+/test_pattern/);+print+substr($0,+RSTART+-+10,+RLENGTH+%2B+20);
}'+file|code-block|syntax|javascript|732942|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You could use

<pre><code>awk '/test_pattern/ {
 match($0, /test_pattern/); print substr($0, RSTART - 10, RLENGTH + 20);
}' file
</code></pre>

blocks|key|516499|text|前3个字符，后4个字符|type|unstyled|depth|inlineStyleRanges|entityRanges|data|516500|$>+echo+"some123_string_and_another"+%7C+grep+-o+-P+'.{0,3}string.{0,4}'
23_string_and|code-block|syntax|javascript|516501|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

3 characters before and 4 characters after

<pre><code>$&gt; echo "some123_string_and_another" | grep -o -P '.{0,3}string.{0,4}'
23_string_and
</code></pre>

blocks|key|732991|text|你的意思是，像这样：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|732992|grep+-o+'.\{0,20\}test_pattern.\{0,20\}'+file|code-block|syntax|javascript|732993|732994|这将在test_pattern的两侧打印最多20个字符。\{0,20\}表示法类似于*，但是指定了0到20次重复，而不是零，或者more.The+-o说只显示匹配本身，而不是整行。|offset|length|style|CODE|732995|entityMap^0|0|0|0|3|C|S|8|16|1|21|2|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Q|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|R|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|S|8|@$J|T|K|U|L|M]|$J|V|K|W|L|M]|$J|X|K|Y|L|M]|$J|Z|K|10|L|M]]|9|@]|A|$]]|$1|N|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|O|$]]

You mean, like this:

<pre><code>grep -o '.\{0,20\}test_pattern.\{0,20\}' file
</code></pre>

?

That will print up to twenty characters on either side of <code>test_pattern</code>. The <code>\{0,20\}</code> notation is like <code>*</code>, but specifies zero to twenty repetitions instead of zero or more.The <code>-o</code> says to show only the match itself, rather than the entire line.

blocks|key|516575|text|grep+-E+-o+".{0,5}test_pattern.{0,5}"+test.txt+|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|516576|这将在您的模式之前和之后匹配最多5个字符。-o开关告诉grep仅显示匹配，并告诉-E使用扩展正则表达式。确保用引号将表达式括起来，否则它可能会被shell解释。|unstyled|516577|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>grep -E -o ".{0,5}test_pattern.{0,5}" test.txt 
</code></pre>

This will match up to 5 characters before and after your pattern. The -o switch tells grep to only show the match and -E to use an extended regular expression. Make sure to put the quotes around your expression, else it might be interpreted by the shell.

blocks|key|516633|text|对于gawk，您可以使用match函数：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|516634|++++x="hey+there+how+are+you"
++++echo+"$x"+%7Cawk+--re-interval+'{match($0,/(.{4})how(.{4})/,a);print+a[1],a[2]}'
++++ere+++are|code-block|syntax|javascript|516635|如果您可以使用perl，则可以使用更灵活的解决方案:下面将打印模式前的3个字符，然后是实际模式，然后是模式后的5个字符。|516636|echo+hey+there+how+are+you+%7Cperl+-lne+'print+"$1$2$3"+if+/(.{3})(there)(.{5})/'
ey+there+how|516637|这也可以应用于单词，而不仅仅是characters.Following将在实际匹配字符串之前打印一个单词。|516638|echo+hey+there+how+are+you+%7Cperl+-lne+'print+$1+if+/(\w%2B)+there/'
hey|516639|下面将在模式后打印一个单词：|516640|echo+hey+there+how+are+you+%7Cperl+-lne+'print+$2+if+/(\w%2B)+there+(\w%2B)/'
how|516641|下面将打印模式前的一个单词，然后是实际的单词，然后是模式后的一个单词：|516642|echo+hey+there+how+are+you+%7Cperl+-lne+'print+"$1$2$3"+if+/(\w%2B)(+there+)(\w%2B)/'
hey+there+how|516643|entityMap^0|2|4|0|0|7|4|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@$9|13|A|14|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|15|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|16|8|@$9|17|A|18|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|19|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|1A|8|@]|D|@]|E|$]]|$1|Q|3|R|5|H|7|1B|8|@]|D|@]|E|$I|J]]|$1|S|3|T|5|6|7|1C|8|@]|D|@]|E|$]]|$1|U|3|V|5|H|7|1D|8|@]|D|@]|E|$I|J]]|$1|W|3|X|5|6|7|1E|8|@]|D|@]|E|$]]|$1|Y|3|Z|5|H|7|1F|8|@]|D|@]|E|$I|J]]|$1|10|3|-4|5|6|7|1G|8|@]|D|@]|E|$]]]|11|$]]

With <code>gawk</code> , you can use match function:

<pre><code> x="hey there how are you"
 echo "$x" |awk --re-interval '{match($0,/(.{4})how(.{4})/,a);print a[1],a[2]}'
 ere are
</code></pre>

If you are ok with <code>perl</code>, more flexible solution : Following will print three characters before the pattern followed by actual pattern and then 5 character after the pattern. 

<pre><code>echo hey there how are you |perl -lne 'print "$1$2$3" if /(.{3})(there)(.{5})/'
ey there how
</code></pre>

This can also be applied to words instead of just characters.Following will print one word before the actual matching string. 

<pre><code>echo hey there how are you |perl -lne 'print $1 if /(\w+) there/'
hey
</code></pre>

Following will print one word after the pattern:

<pre><code>echo hey there how are you |perl -lne 'print $2 if /(\w+) there (\w+)/'
how
</code></pre>

Following will print one word before the pattern , then the actual word and then one word after the pattern:

<pre><code>echo hey there how are you |perl -lne 'print "$1$2$3" if /(\w+)( there )(\w+)/'
hey there how
</code></pre>

blocks|key|516713|text|可以使用regexp+grep进行查找%2B+second+grep进行高亮显示|type|unstyled|depth|inlineStyleRanges|entityRanges|data|516714|echo+"some123_string_and_another"+%7C+grep+-o+-P+'.{0,3}string.{0,4}'+%7C+grep+string|code-block|syntax|javascript|516715|23_string_and|516716|​|516717|📷|atomic|offset|length|516718|516719|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/b55e67ef3b6d2eda6961772b291da95a.png|imageAlt^0|0|0|0|0|0|1|0|0|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|10|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|11|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|12|8|@]|9|@]|A|$]]|$1|K|3|L|5|M|7|13|8|@]|9|@$N|14|O|15|1|16]]|A|$]]|$1|P|3|J|5|6|7|17|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|18|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X|Y|-4]]]]

You can use regexp grep for finding + second grep for highlight

<pre><code>echo "some123_string_and_another" | grep -o -P '.{0,3}string.{0,4}' | grep string
</code></pre>

23_string_and

<a href="https://i.stack.imgur.com/sXXcZ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/sXXcZ.png" alt="enter image description here"></a>

blocks|key|733211|text|我永远不会轻易记住这些神秘的命令修饰符，所以我将top+answer转换为我的~/.bashrc文件中的一个函数：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|733212|cgrep()+{
++++#+For+files+that+are+arrays+10's+of+thousands+of+characters+print.
++++#+Use+cpgrep+to+print+30+characters+before+and+after+search+pattern.
++++if+[+$#+-eq+2+]+;+then
++++++++#+Format+was+'cgrep+"search+string"+/path/to/filename'
++++++++grep+-o+-P+".{0,30}$1.{0,30}"+"$2"
++++else
++++++++#+Format+was+'cat+/path/to/filename+%7C+cgrep+"search+string"
++++++++grep+-o+-P+".{0,30}$1.{0,30}"
++++fi
}+#+cgrep()|code-block|syntax|javascript|733213|下面是它的实际效果：|733214|$+ll+/tmp/rick/scp.Mf7UdS/Mf7UdS.Source

-rw-r--r--+1+rick+rick+25780+Jul++3+19:05+/tmp/rick/scp.Mf7UdS/Mf7UdS.Source

$+cat+/tmp/rick/scp.Mf7UdS/Mf7UdS.Source+%7C+cgrep+"Link+to+iconic"

1:43:30.3540244000+/mnt/e/bin/Link+to+iconic+S+-rwxrwxrwx+777+rick+1000+ri

$+cgrep+"Link+to+iconic"+/tmp/rick/scp.Mf7UdS/Mf7UdS.Source

1:43:30.3540244000+/mnt/e/bin/Link+to+iconic+S+-rwxrwxrwx+777+rick+1000+ri|733215|有问题的文件是一个连续的25K行，使用常规的grep找不到你想要的东西。|733216|注意您可以通过两种不同的方式调用parallels+grep方法的cgrep。|733217|有一种创建函数的"niftier“方法，其中"$2”仅在设置时传递，这将节省4行代码。不过我手头上没有。就像${parm2}+$parm2一样。如果我找到了，我会修改函数和这个答案。|733218|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/8101776/6929343^0|13|9|O|A|0|0|0|0|0|M|4|0|Q|4|X|5|0|1I|F|0^^$0|@$1|2|3|4|5|6|7|12|8|@$9|13|A|14|B|C]]|D|@$9|15|A|16|1|17]]|E|$]]|$1|F|3|G|5|H|7|18|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|19|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|1A|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|1B|8|@$9|1C|A|1D|B|C]]|D|@]|E|$]]|$1|Q|3|R|5|6|7|1E|8|@$9|1F|A|1G|B|C]|$9|1H|A|1I|B|C]]|D|@]|E|$]]|$1|S|3|T|5|6|7|1J|8|@$9|1K|A|1L|B|C]]|D|@]|E|$]]|$1|U|3|-4|5|6|7|1M|8|@]|D|@]|E|$]]]|V|$W|$5|X|Y|Z|E|$10|11]]]]

I'll never easily remember these cryptic command modifiers so I took the <a href="https://stackoverflow.com/a/8101776/6929343">top answer</a> and turned it into a function in my <code>~/.bashrc</code> file:

<pre class="lang-bash prettyprint-override"><code>cgrep() {
 # For files that are arrays 10's of thousands of characters print.
 # Use cpgrep to print 30 characters before and after search pattern.
 if [ $# -eq 2 ] ; then
 # Format was 'cgrep &quot;search string&quot; /path/to/filename'
 grep -o -P &quot;.{0,30}$1.{0,30}&quot; &quot;$2&quot;
 else
 # Format was 'cat /path/to/filename | cgrep &quot;search string&quot;
 grep -o -P &quot;.{0,30}$1.{0,30}&quot;
 fi
} # cgrep()
</code></pre>
Here's what it looks like in action:
<pre class="lang-bash prettyprint-override"><code>$ ll /tmp/rick/scp.Mf7UdS/Mf7UdS.Source

-rw-r--r-- 1 rick rick 25780 Jul 3 19:05 /tmp/rick/scp.Mf7UdS/Mf7UdS.Source

$ cat /tmp/rick/scp.Mf7UdS/Mf7UdS.Source | cgrep &quot;Link to iconic&quot;

1:43:30.3540244000 /mnt/e/bin/Link to iconic S -rwxrwxrwx 777 rick 1000 ri

$ cgrep &quot;Link to iconic&quot; /tmp/rick/scp.Mf7UdS/Mf7UdS.Source

1:43:30.3540244000 /mnt/e/bin/Link to iconic S -rwxrwxrwx 777 rick 1000 ri

</code></pre>
The file in question is one continuous 25K line and it is hopeless to find what you are looking for using regular <code>grep</code>.
Notice the two different ways you can call <code>cgrep</code> that parallels <code>grep</code> method.
There is a &quot;niftier&quot; way of creating the function where &quot;$2&quot; is only passed when set which would save 4 lines of code. I don't have it handy though. Something like <code>${parm2} $parm2</code>. If I find it I'll revise the function and this answer.

Using this:

<pre><code>grep -A1 -B1 "test_pattern" file
</code></pre>

will produce one line before and after the matched pattern in the file. Is there a way to display not lines but a specified number of characters? 

The lines in my file are pretty big so I am not interested in printing the entire line but rather only observe the match in context. Any suggestions on how to do this?

Grep characters before and after match?

使用以下命令：grep -A1 -B1 "test_pattern" file将在文件中匹配的模式之前和之后生成一行。有没有一种方法可以不显示行而显示指定数量的字符？我的文件中的行非常大，所以我对打印整行不感兴趣，而只是观察上下文中的匹配。对如何做到这一点有什么建议吗？

问匹配前后的Grep字符？
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