awk命令详解
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同样的,每个知识点的学习都是来自项目驱动。
今天看了一个开源的框架:dtf
下面是关于dtf的介绍:
The Android Device Testing Framework ("dtf") is a data collection and analysis framework to help individuals answer the question: "Where are the vulnerabilities on this mobile device?" Dtf provides a modular approach and built-in APIs that allows testers to quickly create scripts to interact with their Android devices. By default, dtf does not include any modules, but a collection of testing modules is made available on the Cobra Den website. These modules allow testers to obtain information from their Android device, process this information into databases, and then start searching for vulnerabilities (all without requiring root privileges). These modules help you focus on changes made to AOSP components such as applications, frameworks, system services, as well as lower-level components such as binaries, libraries, and device drivers. In addition, you'll be able to analyze new functionality implemented by the OEMs and other parties to find vulnerabilities.
在浏览dtf的代码过程中,其中有一部分是用来判断你所使用的os的:
ver=$(lsb_release -d|awk -F"\t" '{print $2}')# Ubuntu os_ver=$(echo $ver | awk '{ string=substr($0, 1, 6); print string; }' )if [ "$os_ver" = "Ubuntu" ]; then ubuntu_ver=$(echo $ver | awk '{ string=substr($0, 1, 10); print string; }' ) # Is it the supported one? if [ "$ubuntu_ver" = "Ubuntu 14." -o "$ubuntu_ver" = "Ubuntu 15." ]; then echo "[+] Supported Ubuntu detected." else echo "[WARNING] It looks like you're using Ubuntu, but not the offically supported version." echo -n "Do you want to try the setup anyways? [y/N] " read response case $response in [yY][eE][sS]|[yY]) ;; *) echo "Exiting." exit 0 ;; esac fi# Something else. Bail.else echo "[ERROR] You're not using Ubuntu. You'll need to install dependencies manually. Sorry!" exit 2fi你会看到其中使用到了awk这个命令,对于这个命令之前虽然也使用过,但是认识不清晰,今天来做一个总结:
起步上台
我从netstat命令中提取了如下信息作为用例:
$
cat
netstat
.txt
Proto Recv-Q Send-Q Local-Address Foreign-Address State
tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:9000 0.0.0.0:* LISTEN
tcp 0 0 coolshell.cn:80 124.205.5.146:18245 TIME_WAIT
tcp 0 0 coolshell.cn:80 61.140.101.185:37538 FIN_WAIT2
tcp 0 0 coolshell.cn:80 110.194.134.189:1032 ESTABLISHED
tcp 0 0 coolshell.cn:80 123.169.124.111:49809 ESTABLISHED
tcp 0 0 coolshell.cn:80 116.234.127.77:11502 FIN_WAIT2
tcp 0 0 coolshell.cn:80 123.169.124.111:49829 ESTABLISHED
tcp 0 0 coolshell.cn:80 183.60.215.36:36970 TIME_WAIT
tcp 0 4166 coolshell.cn:80 61.148.242.38:30901 ESTABLISHED
tcp 0 1 coolshell.cn:80 124.152.181.209:26825 FIN_WAIT1
tcp 0 0 coolshell.cn:80 110.194.134.189:4796 ESTABLISHED
tcp 0 0 coolshell.cn:80 183.60.212.163:51082 TIME_WAIT
tcp 0 1 coolshell.cn:80 208.115.113.92:50601 LAST_ACK
tcp 0 0 coolshell.cn:80 123.169.124.111:49840 ESTABLISHED
tcp 0 0 coolshell.cn:80 117.136.20.85:50025 FIN_WAIT2
tcp 0 0 :::22 :::* LISTEN
下面是最简单最常用的awk示例,其输出第1列和第4例,
- 其中单引号中的被大括号括着的就是awk的语句,注意,其只能被单引号包含。
- 其中的$1..$n表示第几例。注:$0表示整个行。
$
awk
'{print $1, $4}'
netstat
.txt
Proto Local-Address
tcp 0.0.0.0:3306
tcp 0.0.0.0:80
tcp 127.0.0.1:9000
tcp coolshell.cn:80
tcp coolshell.cn:80
tcp coolshell.cn:80
tcp coolshell.cn:80
tcp coolshell.cn:80
tcp coolshell.cn:80
tcp coolshell.cn:80
tcp coolshell.cn:80
tcp coolshell.cn:80
tcp coolshell.cn:80
tcp coolshell.cn:80
tcp coolshell.cn:80
tcp coolshell.cn:80
tcp coolshell.cn:80
tcp :::22
我们再来看看awk的格式化输出,和C语言的printf没什么两样:
$
awk
'{printf "%-8s %-8s %-8s %-18s %-22s %-15s\n",$1,$2,$3,$4,$5,$6}'
netstat
.txt
Proto Recv-Q Send-Q Local-Address Foreign-Address State
tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:9000 0.0.0.0:* LISTEN
tcp 0 0 coolshell.cn:80 124.205.5.146:18245 TIME_WAIT
tcp 0 0 coolshell.cn:80 61.140.101.185:37538 FIN_WAIT2
tcp 0 0 coolshell.cn:80 110.194.134.189:1032 ESTABLISHED
tcp 0 0 coolshell.cn:80 123.169.124.111:49809 ESTABLISHED
tcp 0 0 coolshell.cn:80 116.234.127.77:11502 FIN_WAIT2
tcp 0 0 coolshell.cn:80 123.169.124.111:49829 ESTABLISHED
tcp 0 0 coolshell.cn:80 183.60.215.36:36970 TIME_WAIT
tcp 0 4166 coolshell.cn:80 61.148.242.38:30901 ESTABLISHED
tcp 0 1 coolshell.cn:80 124.152.181.209:26825 FIN_WAIT1
tcp 0 0 coolshell.cn:80 110.194.134.189:4796 ESTABLISHED
tcp 0 0 coolshell.cn:80 183.60.212.163:51082 TIME_WAIT
tcp 0 1 coolshell.cn:80 208.115.113.92:50601 LAST_ACK
tcp 0 0 coolshell.cn:80 123.169.124.111:49840 ESTABLISHED
tcp 0 0 coolshell.cn:80 117.136.20.85:50025 FIN_WAIT2
tcp 0 0 :::22 :::* LISTEN
脱掉外套
过滤记录
我们再来看看如何过滤记录(下面过滤条件为:第三列的值为0 && 第6列的值为LISTEN)
$
awk
'$3==0 && $6=="LISTEN" '
netstat
.txt
tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:9000 0.0.0.0:* LISTEN
tcp 0 0 :::22 :::* LISTEN
其中的“==”为比较运算符。其他比较运算符:!=, >, <, >=, <=
我们来看看各种过滤记录的方式:
$
awk
' $3>0 {print $0}'
netstat
.txt
Proto Recv-Q Send-Q Local-Address Foreign-Address State
tcp 0 4166 coolshell.cn:80 61.148.242.38:30901 ESTABLISHED
tcp 0 1 coolshell.cn:80 124.152.181.209:26825 FIN_WAIT1
tcp 0 1 coolshell.cn:80 208.115.113.92:50601 LAST_ACK
如果我们需要表头的话,我们可以引入内建变量NR:
$
awk
'$3==0 && $6=="LISTEN" || NR==1 '
netstat
.txt
Proto Recv-Q Send-Q Local-Address Foreign-Address State
tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:9000 0.0.0.0:* LISTEN
tcp 0 0 :::22 :::* LISTEN
再加上格式化输出:
$
awk
'$3==0 && $6=="LISTEN" || NR==1 {printf "%-20s %-20s %s\n",$4,$5,$6}'
netstat
.txt
Local-Address Foreign-Address State
0.0.0.0:3306 0.0.0.0:* LISTEN
0.0.0.0:80 0.0.0.0:* LISTEN
127.0.0.1:9000 0.0.0.0:* LISTEN
:::22 :::* LISTEN
内建变量
说到了内建变量,我们可以来看看awk的一些内建变量:
$0当前记录(这个变量中存放着整个行的内容)$1~$n当前记录的第n个字段,字段间由FS分隔FS输入字段分隔符 默认是空格或TabNF当前记录中的字段个数,就是有多少列NR已经读出的记录数,就是行号,从1开始,如果有多个文件话,这个值也是不断累加中。FNR当前记录数,与NR不同的是,这个值会是各个文件自己的行号RS输入的记录分隔符, 默认为换行符OFS输出字段分隔符, 默认也是空格ORS输出的记录分隔符,默认为换行符FILENAME当前输入文件的名字怎么使用呢,比如:我们如果要输出行号:
$
awk
'$3==0 && $6=="ESTABLISHED" || NR==1 {printf "%02s %s %-20s %-20s %s\n",NR, FNR, $4,$5,$6}'
netstat
.txt
01 1 Local-Address Foreign-Address State
07 7 coolshell.cn:80 110.194.134.189:1032 ESTABLISHED
08 8 coolshell.cn:80 123.169.124.111:49809 ESTABLISHED
10 10 coolshell.cn:80 123.169.124.111:49829 ESTABLISHED
14 14 coolshell.cn:80 110.194.134.189:4796 ESTABLISHED
17 17 coolshell.cn:80 123.169.124.111:49840 ESTABLISHED
指定分隔符
$
awk
'BEGIN{FS=":"} {print $1,$3,$6}'
/etc/passwd
root 0
/root
bin 1
/bin
daemon 2
/sbin
adm 3
/var/adm
lp 4
/var/spool/lpd
sync
5
/sbin
shutdown
6
/sbin
halt 7
/sbin
上面的命令也等价于:(-F的意思就是指定分隔符)
$
awk
-F:
'{print $1,$3,$6}'
/etc/passwd
注:如果你要指定多个分隔符,你可以这样来:
awk
-F
'[;:]'
再来看一个以\t作为分隔符输出的例子(下面使用了/etc/passwd文件,这个文件是以:分隔的):
$
awk
-F:
'{print $1,$3,$6}'
OFS=
"\t"
/etc/passwd
root 0
/root
bin 1
/bin
daemon 2
/sbin
adm 3
/var/adm
lp 4
/var/spool/lpd
sync
5
/sbin
脱掉衬衫
字符串匹配
我们再来看几个字符串匹配的示例:
$
awk
'$6 ~ /FIN/ || NR==1 {print NR,$4,$5,$6}'
OFS=
"\t"
netstat
.txt
1 Local-Address Foreign-Address State
6 coolshell.cn:80 61.140.101.185:37538 FIN_WAIT2
9 coolshell.cn:80 116.234.127.77:11502 FIN_WAIT2
13 coolshell.cn:80 124.152.181.209:26825 FIN_WAIT1
18 coolshell.cn:80 117.136.20.85:50025 FIN_WAIT2
$ $
awk
'$6 ~ /WAIT/ || NR==1 {print NR,$4,$5,$6}'
OFS=
"\t"
netstat
.txt
1 Local-Address Foreign-Address State
5 coolshell.cn:80 124.205.5.146:18245 TIME_WAIT
6 coolshell.cn:80 61.140.101.185:37538 FIN_WAIT2
9 coolshell.cn:80 116.234.127.77:11502 FIN_WAIT2
11 coolshell.cn:80 183.60.215.36:36970 TIME_WAIT
13 coolshell.cn:80 124.152.181.209:26825 FIN_WAIT1
15 coolshell.cn:80 183.60.212.163:51082 TIME_WAIT
18 coolshell.cn:80 117.136.20.85:50025 FIN_WAIT2
上面的第一个示例匹配FIN状态, 第二个示例匹配WAIT字样的状态。其实 ~ 表示模式开始。/ /中是模式。这就是一个正则表达式的匹配。
其实awk可以像grep一样的去匹配第一行,就像这样:
$
awk
'/LISTEN/'
netstat
.txt
tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:9000 0.0.0.0:* LISTEN
tcp 0 0 :::22 :::* LISTEN
我们可以使用 “/FIN|TIME/” 来匹配 FIN 或者 TIME :
$
awk
'$6 ~ /FIN|TIME/ || NR==1 {print NR,$4,$5,$6}'
OFS=
"\t"
netstat
.txt
1 Local-Address Foreign-Address State
5 coolshell.cn:80 124.205.5.146:18245 TIME_WAIT
6 coolshell.cn:80 61.140.101.185:37538 FIN_WAIT2
9 coolshell.cn:80 116.234.127.77:11502 FIN_WAIT2
11 coolshell.cn:80 183.60.215.36:36970 TIME_WAIT
13 coolshell.cn:80 124.152.181.209:26825 FIN_WAIT1
15 coolshell.cn:80 183.60.212.163:51082 TIME_WAIT
18 coolshell.cn:80 117.136.20.85:50025 FIN_WAIT2
再来看看模式取反的例子:
$
awk
'$6 !~ /WAIT/ || NR==1 {print NR,$4,$5,$6}'
OFS=
"\t"
netstat
.txt
1 Local-Address Foreign-Address State
2 0.0.0.0:3306 0.0.0.0:* LISTEN
3 0.0.0.0:80 0.0.0.0:* LISTEN
4 127.0.0.1:9000 0.0.0.0:* LISTEN
7 coolshell.cn:80 110.194.134.189:1032 ESTABLISHED
8 coolshell.cn:80 123.169.124.111:49809 ESTABLISHED
10 coolshell.cn:80 123.169.124.111:49829 ESTABLISHED
12 coolshell.cn:80 61.148.242.38:30901 ESTABLISHED
14 coolshell.cn:80 110.194.134.189:4796 ESTABLISHED
16 coolshell.cn:80 208.115.113.92:50601 LAST_ACK
17 coolshell.cn:80 123.169.124.111:49840 ESTABLISHED
19 :::22 :::* LISTEN
或是:
awk
'!/WAIT/'
netstat
.txt
折分文件
awk拆分文件很简单,使用重定向就好了。下面这个例子,是按第6例分隔文件,相当的简单(其中的NR!=1表示不处理表头)。
$
awk
'NR!=1{print > $6}'
netstat
.txt
$
ls
ESTABLISHED FIN_WAIT1 FIN_WAIT2 LAST_ACK LISTEN
netstat
.txt TIME_WAIT
$
cat
ESTABLISHED
tcp 0 0 coolshell.cn:80 110.194.134.189:1032 ESTABLISHED
tcp 0 0 coolshell.cn:80 123.169.124.111:49809 ESTABLISHED
tcp 0 0 coolshell.cn:80 123.169.124.111:49829 ESTABLISHED
tcp 0 4166 coolshell.cn:80 61.148.242.38:30901 ESTABLISHED
tcp 0 0 coolshell.cn:80 110.194.134.189:4796 ESTABLISHED
tcp 0 0 coolshell.cn:80 123.169.124.111:49840 ESTABLISHED
$
cat
FIN_WAIT1
tcp 0 1 coolshell.cn:80 124.152.181.209:26825 FIN_WAIT1
$
cat
FIN_WAIT2
tcp 0 0 coolshell.cn:80 61.140.101.185:37538 FIN_WAIT2
tcp 0 0 coolshell.cn:80 116.234.127.77:11502 FIN_WAIT2
tcp 0 0 coolshell.cn:80 117.136.20.85:50025 FIN_WAIT2
$
cat
LAST_ACK
tcp 0 1 coolshell.cn:80 208.115.113.92:50601 LAST_ACK
$
cat
LISTEN
tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:9000 0.0.0.0:* LISTEN
tcp 0 0 :::22 :::* LISTEN
$
cat
TIME_WAIT
tcp 0 0 coolshell.cn:80 124.205.5.146:18245 TIME_WAIT
tcp 0 0 coolshell.cn:80 183.60.215.36:36970 TIME_WAIT
tcp 0 0 coolshell.cn:80 183.60.212.163:51082 TIME_WAIT
你也可以把指定的列输出到文件:
awk
'NR!=1{print $4,$5 > $6}'
netstat
.txt
再复杂一点:(注意其中的if-else-if语句,可见awk其实是个脚本解释器)
$
awk
'NR!=1{
if
($6 ~
/TIME
|ESTABLISHED/) print >
"1.txt"
;
else
if
($6 ~
/LISTEN/
) print >
"2.txt"
;
else
print >
"3.txt"
}'
netstat
.txt
$
ls
?.txt
1.txt 2.txt 3.txt
$
cat
1.txt
tcp 0 0 coolshell.cn:80 124.205.5.146:18245 TIME_WAIT
tcp 0 0 coolshell.cn:80 110.194.134.189:1032 ESTABLISHED
tcp 0 0 coolshell.cn:80 123.169.124.111:49809 ESTABLISHED
tcp 0 0 coolshell.cn:80 123.169.124.111:49829 ESTABLISHED
tcp 0 0 coolshell.cn:80 183.60.215.36:36970 TIME_WAIT
tcp 0 4166 coolshell.cn:80 61.148.242.38:30901 ESTABLISHED
tcp 0 0 coolshell.cn:80 110.194.134.189:4796 ESTABLISHED
tcp 0 0 coolshell.cn:80 183.60.212.163:51082 TIME_WAIT
tcp 0 0 coolshell.cn:80 123.169.124.111:49840 ESTABLISHED
$
cat
2.txt
tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:9000 0.0.0.0:* LISTEN
tcp 0 0 :::22 :::* LISTEN
$
cat
3.txt
tcp 0 0 coolshell.cn:80 61.140.101.185:37538 FIN_WAIT2
tcp 0 0 coolshell.cn:80 116.234.127.77:11502 FIN_WAIT2
tcp 0 1 coolshell.cn:80 124.152.181.209:26825 FIN_WAIT1
tcp 0 1 coolshell.cn:80 208.115.113.92:50601 LAST_ACK
tcp 0 0 coolshell.cn:80 117.136.20.85:50025 FIN_WAIT2
统计
下面的命令计算所有的C文件,CPP文件和H文件的文件大小总和。
$
ls
-l *.cpp *.c *.h |
awk
'{sum+=$5} END {print sum}'
2511401
我们再来看一个统计各个connection状态的用法:(我们可以看到一些编程的影子了,大家都是程序员我就不解释了。注意其中的数组的用法)
$
awk
'NR!=1{a[$6]++;} END {for (i in a) print i ", " a[i];}'
netstat
.txt
TIME_WAIT, 3
FIN_WAIT1, 1
ESTABLISHED, 6
FIN_WAIT2, 3
LAST_ACK, 1
LISTEN, 4
再来看看统计每个用户的进程的占了多少内存(注:sum的RSS那一列)
$
ps
aux |
awk
'NR!=1{a[$1]+=$6;} END { for(i in a) print i ", " a[i]"KB";}'
dbus, 540KB
mysql, 99928KB
www, 3264924KB
root, 63644KB
hchen, 6020KB
脱掉内衣
awk脚本
在上面我们可以看到一个END关键字。END的意思是“处理完所有的行的标识”,即然说到了END就有必要介绍一下BEGIN,这两个关键字意味着执行前和执行后的意思,语法如下:
- BEGIN{ 这里面放的是执行前的语句 }
- END {这里面放的是处理完所有的行后要执行的语句 }
- {这里面放的是处理每一行时要执行的语句}
为了说清楚这个事,我们来看看下面的示例:
假设有这么一个文件(学生成绩表):
$
cat
score.txt
Marry 2143 78 84 77
Jack 2321 66 78 45
Tom 2122 48 77 71
Mike 2537 87 97 95
Bob 2415 40 57 62
我们的awk脚本如下(我没有写有命令行上是因为命令行上不易读,另外也在介绍另一种用法):
$
cat
cal
.
awk
#!/bin/awk -f
#运行前
BEGIN {
math = 0
english = 0
computer = 0
printf
"NAME NO. MATH ENGLISH COMPUTER TOTAL\n"
printf
"---------------------------------------------\n"
}
#运行中
{
math+=$3
english+=$4
computer+=$5
printf
"%-6s %-6s %4d %8d %8d %8d\n"
, $1, $2, $3,$4,$5, $3+$4+$5
}
#运行后
END {
printf
"---------------------------------------------\n"
printf
" TOTAL:%10d %8d %8d \n"
, math, english, computer
printf
"AVERAGE:%10.2f %8.2f %8.2f\n"
, math
/NR
, english
/NR
, computer
/NR
}
我们来看一下执行结果:(也可以这样运行 ./cal.awk score.txt)
$
awk
-f
cal
.
awk
score.txt
NAME NO. MATH ENGLISH COMPUTER TOTAL
---------------------------------------------
Marry 2143 78 84 77 239
Jack 2321 66 78 45 189
Tom 2122 48 77 71 196
Mike 2537 87 97 95 279
Bob 2415 40 57 62 159
---------------------------------------------
TOTAL: 319 393 350
AVERAGE: 63.80 78.60 70.00
环境变量
即然说到了脚本,我们来看看怎么和环境变量交互:(使用-v参数和ENVIRON,使用ENVIRON的环境变量需要export)
$ x=5
$ y=10
$
export
y
$
echo
$x $y
5 10
$
awk
-
v
val=$x
'{print $1, $2, $3, $4+val, $5+ENVIRON["y"]}'
OFS=
"\t"
score.txt
Marry 2143 78 89 87
Jack 2321 66 83 55
Tom 2122 48 82 81
Mike 2537 87 102 105
Bob 2415 40 62 72
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