标签：awk基础
awk命令的格式：
awk [options] ‘awk-script‘ input-file ...
options:
-F: 指定Field separator域分隔符
-f: 指定awk-script文件名
awk-script: 指定awk命令
input-file: 指定awk输入文件
awk-script的结构：
由BEGIN,body,END三部分组成
BEGIN格式：
BEGIN ｛ awk-commands }
用于打印表头
初始化变量
BEGIN关键字需要大写
BEGIN关键字可选
BODY格式：
/pattern/ { action }
对于input-file每一行执行一次
END格式：
END { awk-commands }
打印表尾
END关键字需要大写
END关键字可选
print命令：print等同于print $0，$0代表所有记录
# cat employee.txt
101,Johnny Doe,CEO
102,Jason Smith,IT Manager
103,Raj Reddy,Sysadmin
104,Anand Ram,Developer
105,Jane Miller,Sales Manager
# awk -F, ‘{print}‘ employee.txt
101,Johnny Doe,CEO
102,Jason Smith,IT Manager
103,Raj Reddy,Sysadmin
104,Anand Ram,Developer
105,Jane Miller,Sales Manager
# awk -F, ‘{print $0}‘ employee.txt
101,Johnny Doe,CEO
102,Jason Smith,IT Manager
103,Raj Reddy,Sysadmin
104,Anand Ram,Developer
105,Jane Miller,Sales Manager
print 命令：位置参数$1 $2 ... $n,分别代表一行记录的第1列，第2列...第n列
# awk -F, ‘{print $1,$2}‘ employee.txt
101 Johnny Doe
102 Jason Smith
103 Raj Reddy
104 Anand Ram
105 Jane Miller
awk的内置变量：
FS: Input Field Separator 输入域分隔符
OFS: Output Field Separator 输出域分隔符
RS: Input Record Separator 输入记录分隔符
ORS: Output Record Separator 输出记录分隔符
NR: Number of Records 记录编号
FILENAME: Current File Name 输入文件名
FNR: File " Number of Record " 针对文件的记录编号
NF: Number of Field 字段数
FS:
# awk ‘BEGIN { FS=","; print "UserID\tTitle\n------------" } { print $1,$3 } END { print "------------" }‘ employee.txt
UserID Title
------------
101 CEO
102 IT Manager
103 Sysadmin
104 Developer
105 Sales Manager
------------OFS:
# awk ‘BEGIN { FS=","; OFS=":";print "UserID\tTitle\n------------" } { print $1,$3 } END { print "------------" }‘ employee.txt
UserID Title
------------
101:CEO
102:IT Manager
103:Sysadmin
104:Developer
105:Sales Manager
------------
RS:
# cat employee-one-line.txt
101,Johnny Doe:102,Jason Smith:103,Raj Reddy:104,Anand Ram:105,Jane Miller
# awk ‘BEGIN{RS=":"}{print $1}‘ employee-one-line.txt
101,Johnny
102,Jason
103,Raj
104,Anand
105,Jane
# awk ‘BEGIN{FS=",";RS=":"}{print $1}‘ employee-one-line.txt
101
102
103
104
105ORS:
# cat employee-one-line.txt
101,Johnny Doe:102,Jason Smith:103,Raj Reddy:104,Anand Ram:105,Jane Miller
# awk ‘BEGIN{FS=",";RS=":"}{print $1,$2}‘ employee-one-line.txt 101 Johnny Doe
102 Jason Smith
103 Raj Reddy
104 Anand Ram
105 Jane Miller
# awk ‘BEGIN{FS=",";RS=":";ORS="\n----\n"}{print $1,$2}‘ employee-one-line.txt
101 Johnny Doe
----
102 Jason Smith
----
103 Raj Reddy
----
104 Anand Ram
----
105 Jane Miller
----
NR:
# awk ‘BEGIN {FS=",";print "-----------"}{print "Record",NR,"is",$1,$2,$3}‘ employee.txt
-----------
Record 1 is 101 Johnny Doe CEO
Record 2 is 102 Jason Smith IT Manager
Record 3 is 103 Raj Reddy Sysadmin
Record 4 is 104 Anand Ram Developer
Record 5 is 105 Jane Miller Sales Manager
FILENAME :
# awk ‘BEGIN {FS=",";print "-----------"}{print FILENAME,"Record",NR,"is",$1,$2,$3}‘ employee.txt
-----------
employee.txt Record 1 is 101 Johnny Doe CEO
employee.txt Record 2 is 102 Jason Smith IT Manager
employee.txt Record 3 is 103 Raj Reddy Sysadmin
employee.txt Record 4 is 104 Anand Ram Developer
employee.txt Record 5 is 105 Jane Miller Sales Manager
FNR:
# awk ‘BEGIN {FS=",";print "-----------"}{print FILENAME,"Record",NR,"is",$1,$2,$3}‘ employee.txt items.txt
-----------
employee.txt Record 1 is 101 Johnny Doe CEO
employee.txt Record 2 is 102 Jason Smith IT Manager
employee.txt Record 3 is 103 Raj Reddy Sysadmin
employee.txt Record 4 is 104 Anand Ram Developer
employee.txt Record 5 is 105 Jane Miller Sales Manager
items.txt Record 6 is 101 HD Camcorder Video
items.txt Record 7 is 102 Refrigerator Applicance
items.txt Record 8 is 103 MP3 Player Audio
items.txt Record 9 is 104 Tennis Racket Sports
items.txt Record 10 is 105 Laser Printer Office
# awk ‘BEGIN {FS=",";print "-----------"}{print FILENAME,"Record",FNR,"is",$1,$2,$3}‘ employee.txt items.txt
-----------
employee.txt Record 1 is 101 Johnny Doe CEO
employee.txt Record 2 is 102 Jason Smith IT Manager
employee.txt Record 3 is 103 Raj Reddy Sysadmin
employee.txt Record 4 is 104 Anand Ram Developer
employee.txt Record 5 is 105 Jane Miller Sales Manager
items.txt Record 1 is 101 HD Camcorder Video
items.txt Record 2 is 102 Refrigerator Applicance
items.txt Record 3 is 103 MP3 Player Audio
items.txt Record 4 is 104 Tennis Racket Sports
items.txt Record 5 is 105 Laser Printer OfficeNF:输出结果中，第一列是文件名，第二列是记录编号，第三列是每个记录的字段数
# awk -F, ‘{print FILENAME,NR,NF}‘ employee.txt
employee.txt 1 3
employee.txt 2 3
employee.txt 3 3
employee.txt 4 3
employee.txt 5 3
awk变量和操作符：
一元操作符：
+: 返回当前数字
-：取负数
++：自加
--：自减
+：
# cat employee-sal.txt
101,Johnny Doe,CEO,10000
102,Jason Smith,IT Manager,5000
103,Raj Reddy,Sysadmin,4500
104,Anand Ram,Developer,4500
105,Jane Miller,Sales Manager,3000
# awk ‘BEGIN{FS=","}{print +$4}‘ employee-sal.txt
10000
5000
4500
4500
3000
-：
# awk ‘BEGIN{FS=","}{print -$4}‘ employee-sal.txt
-10000
-5000
-4500
-4500
-3000++：pre自加，先自加，再打印变量
# awk ‘BEGIN{FS=","}{print ++$4}‘ employee-sal.txt
10001
5001
4501
4501
3001
--：pre自减，先自减，再打印变量
# awk ‘BEGIN{FS=","}{print --$4}‘ employee-sal.txt
9999
4999
4499
4499
2999
++：post自加，先执行打印变量，再自加
# awk ‘BEGIN{FS=","}{print $4++}‘ employee-sal.txt
10000
5000
4500
4500
3000
# awk ‘BEGIN{FS=","}{$4++;print $4++}‘ employee-sal.txt
10001
5001
4501
4501
3001--：post自减，先执行打印变量，再自减
# awk ‘BEGIN{FS=","}{print $4--}‘ employee-sal.txt
10000
5000
4500
4500
3000
# awk ‘BEGIN{FS=","}{$4--;print $4--}‘ employee-sal.txt
9999
4999
4499
4499
2999
数学运算：
+： 加
-： 减
*： 乘
/: 除
%： 取模
# cat arit.awk
BEGIN{
FS=",";
OFS=",";
item_discount=0;
}
{
item_discount=$4*20/100;
print $1,$2,$3,$4-item_discount,$5-1
}
# cat items.txt
101,HD Camcorder,Video,210,10
102,Refrigerator,Applicance,850,2
103,MP3 Player,Audio,270,15
104,Tennis Racket,Sports,190,20
105,Laser Printer,Office,475,5
# awk -f arit.awk items.txt
101,HD Camcorder,Video,168,9
102,Refrigerator,Applicance,680,1
103,MP3 Player,Audio,216,14
104,Tennis Racket,Sports,152,19
105,Laser Printer,Office,380,4字符操作：
# cat string.awk
BEGIN {
FS=",";
OFS=",";
string1="Hello";
string2="World";
numberstring="100";
string3=string1" "string2;
print "Concatenate string is: " string3;
numberstring+=1;
print "String to number: " numberstring;
}
# awk -f string.awk items.txt
Concatenate string is: Hello World
String to number: 101
赋值运算：
=：赋值
+=: a+=1等同于a=a+1
-=: a-=1等同于a=a-1
*=: a*=2等同于a=a*2
/=: a/=2等同于a=a/2
%=: a%=2等同于a=a%2
# cat total.awk
BEGIN {
total1=total2=total3=total4=total5=10;
total1+= 5; print total1;
total2-= 5; print total2;
total3*= 5; print total3;
total4/= 5; print total4;
total5%= 5; print total5;
}
# awk -f total.awk
15
5
50
2比较运算：
>:
>=:
<:
<=:
==:
!=:
&&:
||:
# cat items.txt 101,HD Camcorder,Video,210,10 102,Refrigerator,Applicance,850,2 103,MP3 Player,Audio,270,15 104,Tennis Racket,Sports,190,20 105,Laser Printer,Office,475,5 # awk -F, ‘$5 <=5‘ items.txt 102,Refrigerator,Applicance,850,2 105,Laser Printer,Office,475,5
# awk -F, ‘$4 < 200‘ items.txt 104,Tennis Racket,Sports,190,20
# awk -F, ‘$4 == 475 && $5 == 5‘ items.txt 105,Laser Printer,Office,475,5
# awk -F, ‘$4 == 475 || $5 == 15‘ items.txt 103,MP3 Player,Audio,270,15 105,Laser Printer,Office,475,5
# awk -F, ‘$3 != "Video"‘ items.txt 102,Refrigerator,Applicance,850,2 103,MP3 Player,Audio,270,15 104,Tennis Racket,Sports,190,20 105,Laser Printer,Office,475,5
正则表达式操作：
~:匹配
!~:不匹配
# awk -F, ‘$3 ~ "ce"‘ items.txt 102,Refrigerator,Applicance,850,2 105,Laser Printer,Office,475,5 # awk -F, ‘$3 !~ "ce"‘ items.txt 101,HD Camcorder,Video,210,10 103,MP3 Player,Audio,270,15 104,Tennis Racket,Sports,190,20
本文出自 “虎虎生威” 博客，请务必保留此出处http://tobeone.blog.51cto.com/817917/1553191
标签：awk基础
原文地址：http://tobeone.blog.51cto.com/817917/1553191
