2.3.2 awk实例练习

悠悠 2022-10-02 06:55 146阅读 0赞

接[上一篇][Link 1]，这里使用的grade.txt 也是和上一篇中的相同。

先来总结一下awk内置变量：

ARGC 命令行参数个数

ARGV 命令行参数排列

ENVIRON 支持队列中系统环境变量的使用

FILENAME awk浏览文件名

FNR 浏览文件的记录数

FS 设置输入域分隔符，等价于命令行-F选项

NF 浏览记录的域个数

NR 已读的记录数

OFS 输出域分隔符

ORS 输出例句分隔符

RS 控制记录分隔符

\[root@wuke shell2\]\# awk '\{print NF,NR,$0\}END\{print FILENAME\}' grade.txt

7 1 M.Tansley 05/99 48311 Green 8 40 44

7 2 J.Lulu 06/99 48317 green 9 24 26

7 3 P.Bunny 02/99 48 Yellow 12 35 28

7 4 J.Troll 07/99 4842 Brown-3 12 26 26

7 5 L.Tansley 05/99 4712 Brown-2 12 30 28

grade.txt

**\#使用 -F 参数指定分隔符**

\[root@wuke shell2\]\# echo $PWD

/opt/shell2

\[root@wuke shell2\]\# echo $PWD |awk -F/ '\{print $NF"\\t"NF\}'

shell23

**\#设置变量名，将27 赋值给变量BASELINE**

\[root@wuke shell2\]\# awk 'BEGIN\{BASELINE="27"\}$6<BASELINE\{print $0\}' grade.txt J.Lulu 06/99 48317 green 9 24 26

J.Troll 07/99 4842 Brown-3 12 26 26

**\#修改数值域取值，注意‘\{\}’**

\[root@wuke shell2\]\# awk '\{if($1=="M.Tansley");print $1,$6,$7\}' grade.txt

M.Tansley 40 44

J.Lulu 24 26

P.Bunny 35 28

J.Troll 26 26

L.Tansley 30 28

\[root@wuke shell2\]\# awk '\{if($1=="M.Tansley") $6=$6-1;print $1,$6,$7\}' grade.txt

M.Tansley 39 44

J.Lulu 24 26

P.Bunny 35 28

J.Troll 26 26

L.Tansley 30 28

**\#修改文本域取值**

**（1）**

\[root@wuke shell2\]\# awk '\{if($1=="J.Troll")print $0\}' grade.txt

J.Troll 07/99 4842 Brown-3 12 26 26

\[root@wuke shell2\]\# awk '\{if($1=="J.Troll");print $0\}' grade.txt

M.Tansley 05/99 48311 Green 8 40 44

J.Lulu 06/99 48317 green 9 24 26

P.Bunny 02/99 48 Yellow 12 35 28

J.Troll 07/99 4842 Brown-3 12 26 26

L.Tansley 05/99 4712 Brown-2 12 30 28

**（2）**

\[root@wuke shell2\]\# awk '\{if($1=="J.Troll")print $1\}' grade.txt

J.Troll

\[root@wuke shell2\]\# awk '\{if($1=="J.Troll");print $1\}' grade.txt

M.Tansley

J.Lulu

P.Bunny

J.Troll

L.Tansley

\[root@wuke shell2\]\# awk '\{if($1=="J.Troll")$1="J.L.Troll";print $1\}' grade.txt

M.Tansley

J.Lulu

P.Bunny

J.L.Troll

L.Tansley

**\#创建新的输出域，这里新的输出域为 diff**

\[root@localhost shell2\]\# awk 'BEGIN\{print "Name \\t Difference"\}\{if($6<$7) diff=$7-$6;print $1,diff\}' grade.txt

Name  Difference

M.Tansley 4

J.Lulu 2

P.Bunny 2

J.Troll 2

L.Tansley 2

\[root@localhost shell2\]\# awk 'BEGIN\{print "Name \\t Difference"\}\{if($6<$7)\{diff=$7-$6;print $1,diff\}\}' grade.txt

Name  Difference

M.Tansley 4

J.Lulu 2

**\#统计某一个域的和，使用‘+=’ 下面的例子统计第六个域的和**

\[root@localhost shell2\]\# awk '(tot+=$3);END\{print "Club student points:" tot\}' grade.txt

M.Tansley 05/99 48311 Green 8 40 44

J.Lulu 06/99 48317 green 9 24 26

P.Bunny 02/99 48 Yellow 12 35 28

J.Troll 07/99 4842 Brown-3 12 26 26

L.Tansley 05/99 4712 Brown-2 12 30 28

Club student points:106230

**\#注意区别，加‘\{\}’则不打印文件**

\[root@localhost shell2\]\# awk '\{(tot+=$3)\};END\{print "Club student points:" tot\}' grade.txt

Club student points:106230

**awk 内置字符串函数**

gsub(r,s) 在整个$0中用s替代r

gsub(r,s,t) 在整个t中使用s替代r

index(s,t) 在返回s中字符串t的第一个位置

length(s) 放回s长度

match(s,r) 测试s是否包含匹配r的字符串

split(s,a,fs) 在fs上将s分成序列a

sprint(fmt,exp) 返回经fmt格式化后的exp

sub(r,s) 用$0中最左边最长的子串代替s

substr(s,p) 返回字符串s中从p开始的后缀部分

substr(s,p,n) 返回字符串s中从p开始长度为n的后缀部分

**\#替换，目标串使用正则表达式格式‘//’**

\[root@localhost shell2\]\# grep '4842' grade.txt

J.Troll 07/99 4842 Brown-3 12 26 26

\[root@localhost shell2\]\# awk 'gsub(/4842/,4899)\{print $0\}' grade.txt

J.Troll 07/99 4899 Brown-3 12 26 26

**\#查询字符串第一次出现的位置，注意使用BEGIN，否则每一行都会打印，字符串使用引号括起来**

\[root@localhost shell2\]\# awk 'BEGIN\{print index("Bunny","ny")\}' grade.txt

**\#长度**

\[root@localhost shell2\]\# awk '$1=="J.Troll"\{print length($1)" "$1\}' grade.txt

7 J.Troll

**\#match 使用： 找不到返回0，找到返模式串在匹配串中的位置，**

**\#注：单独使用 加BEGIN**

\[root@localhost shell2\]\# awk 'BEGIN\{print match("ABCD",/d/)\}'

\[root@localhost shell2\]\# awk 'BEGIN\{print match("ABCD",/D/)\}'

**\#以下两种模式都正确**

\[root@wuke shell2\]\# awk '$1=="J.Lulu"\{print match($1,"u")\}' grade.txt

\[root@wuke shell2\]\# awk '$1=="J.Lulu"\{print match($1,/u/)\}' grade.txt

**\#split 返回字符串数组元素个数**

\[root@wuke shell2\]\# awk 'BEGIN\{print split("123\#456\#789",myarry,"\#")\}'

\[root@wuke shell2\]\# awk 'BEGIN\{print split("123\#456\#789",myarry,"\#");print myarry\[1\],myarry\[2\],myarry\[3\]\}'

123 456 789

**\#sub，发现并替换模式的第一个位置**

\[root@wuke shell2\]\# awk '$1=="J.Troll"\{print $0\}' grade.txt

J.Troll 07/99 4842 Brown-3 12 26 26

\[root@wuke shell2\]\# awk '$1=="J.Troll"\{sub(26,29,$0) ;print $0\}' grade.txt

J.Troll 07/99 4842 Brown-3 12 29 26

\[root@wuke shell2\]\# awk '$1=="J.Troll"\{sub(26,29,$0)\} \{print $0\}' grade.txt

M.Tansley 05/99 48311 Green 8 40 44

J.Lulu 06/99 48317 green 9 24 26

P.Bunny 02/99 48 Yellow 12 35 28

J.Troll 07/99 4842 Brown-3 12 29 26

L.Tansley 05/99 4712 Brown-2 12 30 28

**\#substr，返回字符串指定范围内的子串**

\[root@wuke shell2\]\# awk '$1=="L.Tansley"\{print substr($1,1,5)\}' grade.txt

L.Tan

**\#使用substr返回指定位置开始的后缀部分，范围只给了一个参数，注意和上一个例子相对比**

\[root@wuke shell2\]\# awk '\{print $1\}' grade.txt

M.Tansley

J.Lulu

P.Bunny

J.Troll

L.Tansley

\[root@wuke shell2\]\# awk '\{print substr($1,3)\}' grade.txt

Tansley

Lulu

Bunny

Troll

Tansley

**\#从shell中向awk传递字符串，通过 echo 加管道的方式**

\[root@wuke shell2\]\# echo "Test" |awk '\{print length($0)\}'

\[root@wuke shell2\]\# STR="mydoc.txt"

\[root@wuke shell2\]\# echo $STR|awk '\{print substr($STR,7)\}'

txt

**awk 使用printf**

**\#printf使用类似于C语言**

**\#字符转换**

\[root@wuke shell2\]\# echo "65"|awk '\{printf "%c\\n",$0\}'

\[root@wuke shell2\]\# echo "99"|awk '\{printf "%f\\n",$0\}'

99.000000

\[root@wuke shell2\]\# echo "99" |awk '\{printf "%10.2f\\n",$0\}'

99.00

\#格式化输出

\#打印名字，左对齐，使用‘-’

\[root@wuke shell2\]\# awk '\{printf "%-15s %s\\n",$1,$3\}' grade.txt M.Tansley 48311

J.Lulu 48317

P.Bunny 48

J.Troll 4842

L.Tansley 4712

**\#向awk传入参数**

\[root@wuke shell2\]\# awk '\{if($5<AGE)print $0\}' AGE=10 grade.txt M.Tansley 05/99 48311 Green 8 40 44

J.Lulu 06/99 48317 green 9 24 26

\[root@wuke shell2\]\# df -k | awk '($4~/^\[0-9\]/)\{if ($4>TRIGGER)print $6"\\t"$4\}' TRIGGER=80000

/13286720

/dev/shm506096

/boot243511

**\#awk脚本**

**下面的脚本是将该命令翻译成为一个完整脚本的形式：**awk '(tot+=$6); END\{print "Club student total points: " tot\}' grade.txt

!/bin/awk -f

\#print a header first

BEGIN\{

print "Student Date Member No. Grade Age Points Max"

print "Name Joined Gained Point Available"

print "==================================================================="

\#let's add the scores of points gained

(tot+=$6)

\#finished processing

END\{

print "Club student total points :" tot

print "Average Club Student points:" tot/NR

\[root@wuke shell2\]\# ./test.awk grade.txt

Student Date Member No. Grade Age Points Max

Name Joined Gained Point Available

===================================================================

M.Tansley 05/99 48311 Green 8 40 44

J.Lulu 06/99 48317 green 9 24 26

P.Bunny 02/99 48 Yellow 12 35 28

J.Troll 07/99 4842 Brown-3 12 26 26

L.Tansley 05/99 4712 Brown-2 12 30 28

Club student total points :155

Average Club Student points:31

**\#一个文件中如果有相同的行连续出现就只打印一次**

stip.txt:

INVALID LCSD 98GJ23  
ERROR\*  
ERROR\*  
CAUTION LPSS ERROR ON ACC NO.  
ERROR\*  
ERROR\*  
ERROR\*  
ERROR\*  
ERROR\*  
PASS FILED INVALID ON GHSI  
ERROR\*  
CUTION LPSS ERROR ON ACC NO.  
ERROR\*  
ERROR\*

strip.awk:

\#!/bin/awk -f

\#error\_strip.awk

\#to call: error\_strip.awk <filename>

\#strips out the ERROR\* lines if there are more than one

\#ERROR\* lines after each filed record.

BEGIN\{

error\_line=""

\#tell awk the whole is "ERROR \*"

if ($0 == "ERROR\*" && error\_line == "ERROR\*")

next;

error\_line = $0;

\[root@wuke shell2\]\# ./strip.awk strip.txt

INVALID LCSD 98GJ23

ERROR\*

CAUTION LPSS ERROR ON ACC NO.

ERROR\*

PASS FILED INVALID ON GHSI

ERROR\*

CUTION LPSS ERROR ON ACC NO.

ERROR\*

strip2.awk:

!/bin/awk -f

\#error\_strip.awk

\#to call: error\_strip.awk <filename>

\#strips out the ERROR\* lines if there are more than one

\#ERROR\* lines after each filed record.

BEGIN\{

error\_line=""

\#tell awk the whole is "ERROR \*"

if ($0 == "ERROR\*" && error\_line == "ERROR\*")

error\_line = $0;

\[root@wuke shell2\]\# ./strip2.awk strip.txt

INVALID LCSD 98GJ23

ERROR\*

CAUTION LPSS ERROR ON ACC NO.

ERROR\*

PASS FILED INVALID ON GHSI

ERROR\*

CUTION LPSS ERROR ON ACC NO.

ERROR\*

**\#在awk中使用FS变量指定分隔符的时候，FS一定要放在BEGIN部分**

!/bin/awk -f

\#to call :passwd.awk /etc/passwd

\#print out the first and fifth fields

BEGIN\{FS=":"\}

\{print $1"\\t"$5\} **\#第一域是帐号名，第五域是账号所有者**

\[root@wuke shell2\]\# ./passwd.awk /etc/passwd

rootroot

binbin

daemondaemon

admadm

lplp

syncsync

shutdownshutdown

halthalt

mailmail

**\#向AWK脚本传递参数**

\#!/bin/awk -f

\#name: age.awk

\#to call : age.awk AGE=n grade.txt

\#prints ages that are lower than the age supplied on the command line

if ($5<AGE) print $0

\[root@wuke shell2\]\# ./age.awk AGE=10 grade.txt

M.Tansley 05/99 48311 Green 8 40 44

J.Lulu 06/99 48317 green 9 24 26

**\#awk 数组，awk数组是类似于一个键值对，既可以使用数字做下标，也可以使用字符串做下标**

前面介绍过split函数，并使用了一个例子：

$awk 'BEGIN \{print split("123\#456\#789",myarray,"\#")\}'

上面例子中，split返回数组myarray下标数，实际上myarray数组为：

myarray\[1\]="123"

myarray\[2\]="456"

myarray\[3\]="789"

\[root@wuke shell2\]\# awk 'BEGIN\{print split("123\#456\#789",myarray,"\#");print myarray\[1\],myarray\[2\],myarray\[3\]\}'

123 456 789

数组使用前不必定义，也不必指定数组元素个数。经常使用循环来方位数组，一般这样使用循环：

**for（element in array ） print array\[element\]**

\#下面脚本先将"123\#456\#789" 使用split环峰，再循环打印个数组元素

\#!/bin/awk -f

\#name: arraytest.awk

\#prints out an array

BEGIN\{

a="123\#456\#789";

split(a,myarry,"\#")

END\{

for (i in myarry)\{

print myarry\[i\]

**\#要运行脚本 需要使用/dev/null作为输入文件**

\[root@wuke shell2\]\# ./myarry.awk /dev/null

123

456

789

**grade\_student.txt:**

**Yellow\#Junior  
Orange\#Senior  
Yellow\#Junior  
Purple\#Junior  
Brown-2\#Junior  
White\#Senior  
Orange\#Senior  
Red\#Junior  
Brown-2\#Senior  
Yellow\#Senior  
Red\#Junior  
Blue\#Senior  
Green\#Senior  
Purple\#Junior  
White\#Junior**

**belts.awk:**

\#!/bin/awk -f

\#name: belts.awk

\#to call: belts.awk grade2.txt

\#loops through the grade2.txt file and counts how many

\#belts we have in(yellow,orange,red)

\#also count how many adults and juniors we have

\#start of BEGIN

\#set FS and load the arrays and our values

BEGIN\{

FS="\#"

\#load the belt colours we are interested in only