awk 实例练习 （三）

awk 使用printf 

 

#printf使用类似于C语言

#字符转换

zhuyupeng@zhuyupeng-PC ~

$ echo "65" | awk '{printf "%c\n",$0}'

A

 

zhuyupeng@zhuyupeng-PC ~

$ echo "99" | awk '{printf "%f\n",$0}'

99.000000

 

#格式化输出

#打印名字，左对齐，使用‘-’

zhuyupeng@zhuyupeng-PC ~

$ 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

zhuyupeng@zhuyupeng-PC ~

$ 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

 

zhuyupeng@zhuyupeng-PC ~

$ df -k

文件系统                1K-块     已用    可用 已用% 挂载点

D:/Program Files/bin 76155900 70397660 5758240   93% /usr/bin

D:/Program Files/lib 76155900 70397660 5758240   93% /usr/lib

D:/Program Files     76155900 70397660 5758240   93% /

C:                   40857596 32552996 8304600   80% /cygdrive/c

D:                   76155900 70397660 5758240   93% /cygdrive/d

 

zhuyupeng@zhuyupeng-PC ~

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

93%     70397660

93%     70397660

93%     70397660

/cygdrive/c     8304600

/cygdrive/d     5758240

  

 

#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
    } 

 

#脚本运行是通过secureCRT 登陆远程的服务器运行的，控制台略有不同

 

[chen@localhost zyp]$ ./stu_tot.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

 

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;
        print
    }

 

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*

 

[chen@localhost zyp]$ ./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*

 

#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

 

[chen@localhost zyp]$ ./passwd.awk /etc/passwd
root     root
bin      bin
daemon   daemon
adm      adm
lp       lp
sync     sync
shutdown         shutdown
halt     halt
mail     mail
uucp     uucp
operator         operator
games    games
gopher   gopher
ftp      FTP User
nobody   Nobody

...

 

#向AWK脚本传递参数

 

age.awk:

 

#!/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
}

 

grade.txt:(前面已经给出)

 

[chen@localhost zyp]$ ./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,"#")}'

3

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"

 

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{
    record="123#456#789";
    split(record,myarray,"#")
}

END{
    for ( i in myarray )
       {
           print myarray[i]
       }
}

#要运行脚本 需要使用/dev/null作为输入文件

[chen@localhost zyp]$ ./arraytest.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
    belt["Yellow"]
    belt["Orange"]
    belt["Red"]
    #end of BEGIN
    #load the student type
    student["Junior"]
    student["Senior"]
}
#loop thru array that holds the belt colours against field-1
#if we have a match,keep a running total
{ for (colour in belt)
    {
        if ($1==colour)
            belt[colour]++
    }
}
    #loop thru array that holds the student type against
    #field-2 if we have a match, keep a running total
       { for(senior_or_junior in student)
           {
               if($2 == senior_or_junior)
                   student[senior_or_junior]++
           }
       }
    #finished processing so print out the matches..for each array
END{ for(colour in belt)
       print "The club has",belt[colour],colour,"Belts"

        for(senior_or_junior in student)
             print "The club has",student[senior_or_junior]\
                            , senior_or_junior, "students"
   }


##

 

##

脚本的作用：

1.统计Yellow、Orange和Red级别的人各是多少

2.俱乐部中有多少成年（Senior）和未成年人（Junior）

 

 

 

#

[chen@localhost ~]$ ./belts.awk grade_student.txt
The club has 2 Red Belts
The club has 2 Orange Belts
The club has 3 Yellow Belts
The club has 7 Senior students
The club has 8 Junior students