awk 命令 linux命令

awk在其对数据分析并生成报告时，显得尤为强大。简单来说awk就是把文件逐行的读入，以空格为默认分隔符将每行切片，切开的部分再进行各种分析处理。

 zhangyanfen>> last -n 5
jisongg   ftp          135.240.21.194   Sun Nov  8 13:53   still logged in
jisongg   pts/129      ca0070437n1.chn. Sun Nov  8 13:17   still logged in
jisongg   pts/129      ca0070437n1.chn. Sun Nov  8 13:06 - 13:15  (00:08)
jisongg   ftp          135.240.21.194   Sun Nov  8 12:47 - 12:48  (00:01)
jisongg   pts/54       ca0070437n1.chn. Sun Nov  8 12:44   still logged in
 zhangyanfen>> last -n 5 | awk '{print $1}'
jisongg
jisongg
jisongg
jisongg
jisongg

#cat /etc/passwd |awk  -F ':'  '{print $1"\t"$7}'
root    /bin/bash
daemon  /bin/sh
bin     /bin/sh
sys     /bin/sh

 zhangyanfen>> awk '{count++;print $0;} END{print "user count is ", count}' /etc/passwd
root:x:0:1:Super-User:/:/sbin/sh
daemon:x:1:1::/:
bin:x:2:2::/usr/bin:
sys:x:3:3::/:
adm:x:4:4:Admin:/var/adm:
lp:x:71:8:Line Printer Admin:/usr/spool/lp:
uucp:x:5:5:uucp Admin:/usr/lib/uucp:
nuucp:x:9:9:uucp Admin:/var/spool/uucppublic:/usr/lib/uucp/uucico
listen:x:37:4:Network Admin:/usr/net/nls:
nobody:x:60001:60001:Nobody:/:
noaccess:x:60002:60002:No Access User:/:
nobody4:x:65534:65534:SunOS 4.x Nobody:/:
local:x:60000:60000:SDE Local User:/export/home/local:/bin/ksh
sshd:x:155:155:sshd privsep:/var/empty:/bin/false
opc_op:x:777:177:William L'Hotta -0410925 ,,,:/export/home/opc_op:/bin/ksh
user count is  15

 zhangyanfen>> ls -l |awk 'BEGIN {size=0;} {size=size+$5;} END {print "the size is "size/1024/1024 "M"}'
the size is 45.1787M