Linux文本数据提取之head,tail实例详解


提取开头或结尾数行

显示标准输入前n条记录，或者命令行文件列表的每一个的前n条记录：

head -n n [ file(s) ]

head -n [ file(s) ]

awk 'FNR <= n' [ file(s) ]


sed -e nq [ file(s) ]


sed nq [ file(s) ]

 

实例：

①[gz_fieldyang@test ~]$ awk 'FNR <= 3' hello.c

#include<stdio.h>

#int main(){

   
printf("hello,");

[gz_fieldyang@test ~]$ awk 'FNR <= 5' my-friends

#SORTKEY: ma,Kin

Kin ma

zhujiangxincheng 78

D-305 Letaijie

TaiShan

②[gz_fieldyang@test ~]$ head -n 3 my-friends

#SORTKEY: ma,Kin

Kin ma

zhujiangxincheng 78

③[gz_fieldyang@test ~]$ head -3 my-friends    

#SORTKEY: ma,Kin

Kin ma

zhujiangxincheng 78

④[gz_fieldyang@test ~]$ sed -e 4q my-friends

#SORTKEY: ma,Kin

Kin ma

zhujiangxincheng 78

D-305 Letaijie

⑤[gz_fieldyang@test ~]$ sed 3q my-friends   

#SORTKEY: ma,Kin

Kin ma

zhujiangxincheng 78

[gz_fieldyang@test ~]$

 

显示结尾数行：

tail -n n [ file ]

tail -n [ file ]


 

[gz_fieldyang@ test ~]$ tail -n 25 -f /var/log/messages

...

Ctrl C

               
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