blocks|key|471281|text|管子的魔力；|type|unstyled|depth|inlineStyleRanges|entityRanges|data|471282|head+-10+log.txt+%7C+grep+<whatever>|code-block|syntax|javascript|471283|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|$]]

The magic of pipes;

<pre><code>head -10 log.txt | grep &lt;whatever&gt;
</code></pre>

blocks|key|471456|text|对于在谷歌上找到它的人来说，我需要搜索多个文件的前n行，但只打印匹配的文件名。我用过|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|471457|+gawk+'FNR>10+{nextfile}+/pattern/+{+print+FILENAME+;+nextfile+}'+filenames|code-block|syntax|javascript|471458|一旦看到10行，FNR..nextfile就会停止处理文件。只要给定文件中出现第一个匹配项，//..{}就会打印文件名并继续执行操作。要引用文件名以便于其他程序使用，请使用|471459|+gawk+'FNR>10+{nextfile}+/pattern/+{+print+"\""+FILENAME+"\""+;+nextfile+}'+filenames|471460|entityMap^0|P|1|0|0|8|D|1A|6|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|Z|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|P|$]]

For folks who find this on Google, I needed to search the first <code>n</code> lines of multiple files, but to only print the matching filenames. I used

<pre><code> gawk 'FNR&gt;10 {nextfile} /pattern/ { print FILENAME ; nextfile }' filenames
</code></pre>

The <code>FNR..nextfile</code> stops processing a file once 10 lines have been seen. The <code>//..{}</code> prints the filename and moves on whenever the first match in a given file shows up. To quote the filenames for the benefit of other programs, use 

<pre><code> gawk 'FNR&gt;10 {nextfile} /pattern/ { print "\"" FILENAME "\"" ; nextfile }' filenames
</code></pre>

blocks|key|687593|text|或者在没有%7C的情况下对单个进程使用awk|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|687594|awk+'/your_regexp/+&&+NR+<+11'+INPUTFILE|code-block|syntax|javascript|687595|在每一行上，如果your_regexp匹配，并且记录(行数)少于11，它将执行默认操作(即打印输入行)。|687596|或者使用sed|687597|sed+-n+'/your_regexp/p;10q'+INPUTFILE+|687598|检查regexp并打印该行(-n表示不打印输入，否则为默认值)，然后在第10行之后退出。|687599|entityMap^0|5|1|H|3|0|0|8|B|0|4|3|0|0|E|2|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|Z|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|10|8|@$9|11|A|12|B|C]]|D|@]|E|$]]|$1|M|3|N|5|6|7|13|8|@$9|14|A|15|B|C]]|D|@]|E|$]]|$1|O|3|P|5|H|7|16|8|@]|D|@]|E|$I|J]]|$1|Q|3|R|5|6|7|17|8|@$9|18|A|19|B|C]]|D|@]|E|$]]|$1|S|3|-4|5|6|7|1A|8|@]|D|@]|E|$]]]|T|$]]

Or use <code>awk</code> for a single process without <code>|</code>:

<pre><code>awk '/your_regexp/ &amp;&amp; NR &lt; 11' INPUTFILE
</code></pre>

On each line, if <code>your_regexp</code> matches, and the number of records (lines) is less than 11, it executes the default action (which is printing the input line).

Or use <code>sed</code>:

<pre><code>sed -n '/your_regexp/p;10q' INPUTFILE 
</code></pre>

Checks your regexp and prints the line (<code>-n</code> means don't print the input, which is otherwise the default), and quits right after the 10th line.

blocks|key|687450|text|与grep一起使用程序时，您有几个选择。在我看来，最简单的方法是使用head|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|687451|head+-n10+filename+%7C+grep+...|code-block|syntax|javascript|687452|head将输出前10行(使用-n选项)，然后您可以将该输出通过管道传输到grep。|687453|entityMap^0|1|4|Y|4|0|0|0|4|E|2|10|4|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|N|$]]

You have a few options using programs along with <code>grep</code>. The simplest in my opinion is to use <code>head</code>:

<pre><code>head -n10 filename | grep ...
</code></pre>

<code>head</code> will output the first 10 lines (using the <code>-n</code> option), and then you can pipe that output to <code>grep</code>.

blocks|key|687624|text|grep+"pattern"+<(head+-n+10+filename)|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|687625|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>grep "pattern" &lt;(head -n 10 filename)
</code></pre>

blocks|key|471318|text|可以将head+-10+file的输出通过管道传输到grep，以完成此操作：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|471319|head+-10+file+%7C+grep+…|code-block|syntax|javascript|471320|使用Perl：|471321|perl+-ne+'last+if+$.+>+10;+print+if+/pattern/'+file|471322|entityMap^0|3|D|Q|4|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|P|$]]

The output of <code>head -10 file</code> can be piped to <code>grep</code> in order to accomplish this:

<pre><code>head -10 file | grep …
</code></pre>

Using Perl:

<pre><code>perl -ne 'last if $. &gt; 10; print if /pattern/' file
</code></pre>

blocks|key|687558|text|您可以使用以下行：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|687559|head+-n+10+/path/to/file+%7C+grep+[...]|code-block|syntax|javascript|687560|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 can use the following line:

<pre><code>head -n 10 /path/to/file | grep [...]
</code></pre>

blocks|key|471553|text|head+-10+log.txt+%7C+grep+-A+2+-B+2+pattern_to_search|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|471554|-A+2：在图案前打印两行。|unstyled|offset|length|style|CODE|471555|-B+2：在模式后打印两行。|471556|head+-10+log.txt+#+read+the+first+10+lines+of+the+file.|471557|entityMap^0|0|0|4|0|0|4|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|R|8|@$G|S|H|T|I|J]]|9|@]|A|$]]|$1|K|3|L|5|F|7|U|8|@$G|V|H|W|I|J]]|9|@]|A|$]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$B|C]]|$1|O|3|-4|5|F|7|Y|8|@]|9|@]|A|$]]]|P|$]]

<pre><code>head -10 log.txt | grep -A 2 -B 2 pattern_to_search
</code></pre>

<code>-A 2</code>: print two lines before the pattern. 

<code>-B 2</code>: print two lines after the pattern. 

<pre><code>head -10 log.txt # read the first 10 lines of the file.
</code></pre>

blocks|key|471612|text|Joachim+Isaksson回答的一个扩展:通常我需要一个长文件中间的内容，例如5001到5020行，在这种情况下，您可以将head与tail结合使用|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|471613|head+-5020+file.txt+%7C+tail+-20+%7C+grep+x|code-block|syntax|javascript|471614|它获取前5020行，然后只显示其中的最后20行，然后将所有内容通过管道传输到grep。|471615|(编辑:我的示例编号中的fencepost错误，将管道添加到grep)|471616|entityMap^0|1S|4|1X|4|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@]|D|@]|E|$]]|$1|M|3|N|5|6|7|X|8|@]|D|@]|E|$]]|$1|O|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|P|$]]

An extension to Joachim Isaksson's answer: Quite often I need something from the middle of a long file, e.g. lines 5001 to 5020, in which case you can combine <code>head</code> with <code>tail</code>:

<pre><code>head -5020 file.txt | tail -20 | grep x
</code></pre>

This gets the first 5020 lines, then shows only the last 20 of those, then pipes everything to grep.

(Edited: fencepost error in my example numbers, added pipe to grep)

blocks|key|687695|text|grep+-A+10|type|unstyled|depth|inlineStyleRanges|entityRanges|data|687696|这是为了抓取模式和模式之后的下10行。这只适用于一个已知的模式，如果你没有一个已知的模式，请使用"head“建议。|687697|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

grep -A 10 &lt;Pattern&gt;

This is to grab the pattern and the next 10 lines after the pattern. This would work well only for a known pattern, if you don't have a known pattern use the "head" suggestions.

blocks|key|687822|text|grep+-m6+"string"+cov.txt|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|687823|此命令仅搜索string的前6行|unstyled|offset|length|style|CODE|687824|entityMap^0|0|6|6|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|N|8|@$G|O|H|P|I|J]]|9|@]|A|$]]|$1|K|3|-4|5|F|7|Q|8|@]|9|@]|A|$]]]|L|$]]

<pre><code>grep -m6 "string" cov.txt
</code></pre>

This searches only the first 6 lines for <code>string</code>

I have very long log files, is it possible to ask grep to only search the first 10 lines?

Can I grep only the first n lines of a file?

日志文件

Perl

我有很长的日志文件，可以让grep只搜索前10行吗？

问我可以只对文件的前n行进行grep吗？
EN

回答 11

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问我可以只对文件的前n行进行grep吗？EN

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问我可以只对文件的前n行进行grep吗？
EN