1.打印指定行

Q:如何用awk打印某一文件的第3行之后的所有行？

A:可以利用awk的NR变量。

搜索关键字：

http://search.aol.com/aol/search?q=awk+print+all+but+the+first+three+lines

结论：

$ awk 'NR>10' mem_cpu_usage.txt | wc -l
753

$ wc -l mem_cpu_usage.txt
763 mem_cpu_usage.txt

参考链接：

http://askubuntu.com/questions/475694/awk-command-to-print-all-the-lines-except-the-last-three-lines #有性能比较统计！

2.打印指定列

Q:如何用awk打印某一文件的第3列之后的所有列？

A:利用awk进行编程。

搜索关键字：

http://search.aol.com/aol/search?q=awk+print+all+but+the+first+three+columns

结论：

awk '{for(i=1;i<4;i++) $i="";print}' file
awk '{$1=$2=$3="";print}' file
awk '{ $1=""; $2=""; $3=""; print $0 }' file

参考链接：

• http://stackoverflow.com/questions/2961635/using-awk-to-print-all-columns-from-the-nth-to-the-last
• http://stackoverflow.com/questions/2626274/print-all-but-the-first-three-columns
• http://superuser.com/questions/211406/awk-print-from-the-third-field-until-end-of-line-each-word-with-one-space

3.去重

awk '{dict[$2]++}; END{for(i in dict) print dict[i]"\t"i}'    #count

awk '{dict[$2]=dict[$2]+$1}; END{for(i in dict) print dict[i]"\t"i}'	#sum

awk '{type["all"]+=$3; type[$2]+=$3} END{for(i in type) print i"\t"type[i]}'  #sum too

awk '{dict[$1]++}; END{for(i in dict) print dict[i]"\t"i}'  #count

ls -lt web_log/ | awk '$5!=5343{print $5}' | awk '{dict[$1]++}; END{for(i in dict) print dict[i]"\t"i}'
find web_log/ -iname "*.txt" | xargs ls -l | awk '$5!=5343{print $5}' | awk '{dict[$1]++}; END{for(i in dict) print dict[i]"\t"i}'
find web_log/ -iname "*.txt" | xargs ls -l | awk '$5!=5343{print $5}' | awk '{dict[$1]++; dict["all"]++}; END{for(i in dict) print dict[i]"\t"i}'

awk '$5==5343' | wc -l

4.一些应用

awk '$1 !~ /lo/ && NR!=1 && NR!=2' /proc/net/dev | awk 'BEGIN{max=0} {if($2+0 > max+0) max=$2 fi} END{print $1}' | awk -F':' '{print $1}'  #获取网卡名称

awk '$1 !~ /lo/' /proc/net/dev | awk 'BEGIN{max=0} {if($2+0 > max+0) max=$2 fi} END{print $1}' | awk -F':' '{print $1}'  #获取网卡名称