How to use head Command in linux
This article mainly explains the "use of head commands in linux", the content of the explanation is simple and clear, easy to learn and understand, the following please follow the editor's ideas slowly in depth, together to study and learn "the use of head commands in linux" bar!
1. Command format:
Head [parameters]... [file].
2. Command function:
Head is used to display the beginning of an archive to standard output, and the default head command prints the first 10 lines of its corresponding file.
3. Command parameters:
-Q hide file name
-v displays the file name
-c displays the number of bytes
Number of rows displayed by-n
4. Use an example:
Example 1: display the first n lines of the file
Command:
Head-n 5 log2014.log
Output:
The code is as follows:
[root@localhost test] # cat log2014.log
2014-01
2014-02
2014-03
2014-04
2014-05
2014-06
2014-07
2014-08
2014-09
2014-10
2014-11
2014-12
= =
[root@localhost test] # head-n 5 log2014.log
2014-01
2014-02
2014-03
2014-04
2014-05 [root@localhost test] #
Example 2: display the first n bytes of the file
Command:
Head-c 20 log2014.log
Output:
The code is as follows:
[root@localhost test] # head-c 20 log2014.log
2014-01
2014-02
2014
[root@localhost test] #
Example 3: the contents of the file except the last n bytes
Command:
Head-c-32 log2014.log
Output:
The code is as follows:
[root@localhost test] # head-c-32 log2014.log
2014-01
2014-02
2014-03
2014-04
2014-05
2014-06
2014-07
2014-08
2014-09
2014-10
2014-11
2014-12 [root@localhost test] #
Example 4: all the contents of the output file except the last n lines
Command:
Head-n-6 log2014.log
Output:
The code is as follows:
[root@localhost test] # head-n-6 log2014.log
2014-01
2014-02
2014-03
2014-04
2014-05
2014-06
2014-07 [root@localhost test] #
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