awk

awk '{match action[;actions]} file'awk -f _.awk file

script

action:BEGIN{}{__body__}END{}

BEGIN块在开始前执行

END块在结束后执行

按分割的列读取

• $0 整行
• $n 第n列 $10

match

三种匹配方式

• 列匹配 : ColOpVal $2~100 列|运算符|值
• 正则匹配 : /pattern/
• match 函数 : match(value,/pattern/,storage)
  • 使用()匹配子项
  • 使用storage[n]取值

operations

操作符	含义
!	Not
&&	And
||	Or
==	Equal
!=	Not equal
>	Greater
<	Litter
>=	Ge
<=	Le
~	Regex Match
!~	Not Match

action

主要使用 print

条件 if(match){}

控制

• next : 跳过当前记录
• exit : 跳到END

inner variable

变量名	含义
ARGC	命令行变元个数
ARGV	命令行变元数组
FILENAME	当前输入文件名
FNR	当前文件中的记录号
FS	输入域分隔符，默认为一个空格(-F)
OFS	输出域分隔符
RS	输入记录分隔符
NF	当前记录里域个数 number of field
NR	到目前为止记录数 number of the current record
ORS	输出记录分隔符

args

命令行参数

options	meanings
-F	设置内置变量FS值
-v	设置变量 -v var=0
-f	从脚本文件中读取指令

tldr

# Print the fifth column (a.k.a. field) in a space-separated file:
awk '{print $5}' {{filename}}

# Print the second column of the lines containing "foo" in a space-separated file:
awk '/{{foo}}/ {print $2}' {{filename}}

# Print the last column of each line in a file, using a comma (instead of space) as a field separator:
awk -F ',' '{print $NF}' {{filename}}

# Sum the values in the first column of a file and print the total:
awk '{s+=$1} END {print s}' {{filename}}

# Print every third line starting from the first line:
awk 'NR%3==1' {{filename}}

# Print different values based on conditions:
awk '{if ($1 == "foo") print "Exact match foo"; else if ($1 ~ "bar") print "Partial match bar"; else print "Baz"}' {{filename}}

# Print all lines where the 10th column value equals the specified value :
awk '($10 == value)'

# Print all the lines which the 10th column value is between a min and a max :
awk '($10 >= min_value && $10 <= max_value)'

overview