September 15 awk Summary

Awk is the report generator

Awk is the original Aho,weinberger,kernighan three initials

awk is a symbolic link pointing to gawk

AWK is a separate programming language,

Mode: Similar address delimitation

$ A represents an entire line

$1$2$3$4, which represents each unit separated by a space

650) this.width=650; "title=" image "style=" border-right-width:0px;border-bottom-width:0px;border-top-width:0px; " Border= "0" alt= "image" Src= "http://s3.51cto.com/wyfs02/M01/73/85/wKiom1YADj6xcd5sAABcEAXrXVw004.jpg" width= "506" height= "136"/>

-F char is a delimiter

awk [Options] ' program ' file

awk [option] ' pattern{action} ' file

Supported variables:

Built-in variables, custom variables

Built-in variables:

FS: Field delimiter when entering

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "http://s3.51cto.com/wyfs02/M02/73/85/wKiom1YADj6BUrr2AADIDMwaJY4447.jpg" height= "144" />

Rs: Enter the rows separator

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "http://s3.51cto.com/wyfs02/M00/73/85/wKiom1YADj7y6vB3AABtxNlPH9Q273.jpg" height= "141" />

OFS: Field delimiter at output

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "http://s3.51cto.com/wyfs02/M01/73/85/wKiom1YADj_QCZqsAADLvfmKGoI815.jpg" height= "100" />

ORS: Output Rows Separator

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "http://s3.51cto.com/wyfs02/M02/73/85/wKiom1YADj-yi1OxAAFZXJIXPVo513.jpg" height= "108" />

NF: Number of fields in a row

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "http://s3.51cto.com/wyfs02/M00/73/85/wKiom1YADj-zpwm1AAD1hEnCU3k364.jpg" height= "264" />

NR: Number of lines in the file

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "http://s3.51cto.com/wyfs02/M01/73/85/wKiom1YADkDRLMEuAAEaEwXrk0I308.jpg" height= "297" />

FNR: Displays the line number of each file

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "http://s3.51cto.com/wyfs02/M02/73/85/wKiom1YADkCB4GRSAAFymnkP1l8164.jpg" height= "314" />

Awk–f: ' {print $, $NF} '/etc/passwdd equivalent to the command below

Awk–v fs=: ' {print $, $NF} '/etc/passwd

Custom variables

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "http://s3.51cto.com/wyfs02/M00/73/85/wKiom1YADkDjkwOwAADE6RkLQnU412.jpg" height= "180" />

printf command:

printf format,item1,item2

The options for format are:

%c: ASCII code for displaying characters

%d,%i: Display Decimal

%e,%e: Scientific and technological law shows numerical value

%f: Display string

%g,%g: Displaying values in scientific or technical law format or floating-point number format

%s: Display string

%u: Show unsigned integers

Percent: show% itself

Modifier:

#: Width

-Align Left

+ Display numeric symbols

. #取精度值

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "Http://s3.51cto.com/wyfs02/M01/73/85/wKiom1YADkHDzrGCAAB8ye1dykQ770.jpg" height= "86"/ >

Note: Print does not show the meaning of%d, only the characters are displayed

Arithmetic operations: +,-,*,/,+=,-=,*=,/=

If you are =, write/=/

Comparison operators:

<

<=

>

>=

==

!=

~ Left string can match right mode to True

!~ against the previous command

Three-mesh operator:

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "Http://s3.51cto.com/wyfs02/M02/73/83/wKioL1YAEH-CfBNIAAB9v4vKUa4371.jpg" height= "109" />

Pattern, Mode:

1. Regular:/pattern/

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "http://s3.51cto.com/wyfs02/M00/73/83/wKioL1YAEH-j7XYPAAB2HMKcQMw314.jpg" height= "74"/ >

2. Expression:

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "http://s3.51cto.com/wyfs02/M01/73/83/wKioL1YAEH_xfx6kAACvrLl55rA832.jpg" height= "224" />

3, line range, address bound startline endline, etc., with NR to make judgments

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "http://s3.51cto.com/wyfs02/M02/73/83/wKioL1YAEIDzJiBWAACyepXKPtc289.jpg" height= "77"/ >

4, Begin/end Special mode, indicating that before (BEGIN) or after (END) Run 1 times

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "Http://s3.51cto.com/wyfs02/M02/73/83/wKioL1YAEIDgJXb4AABsyfUAd-g489.jpg" height= "99"/ >

5, empty mode, match any row, default mode

Action

1. Expression

2, the control statement If-else,

if (condition) {then Body}else{else body}

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "http://s3.51cto.com/wyfs02/M00/73/85/wKiom1YADkKjNDqoAACAPxeWFJY481.jpg" height= "91"/ >

Do-while

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "Http://s3.51cto.com/wyfs02/M01/73/85/wKiom1YADkOSau3LAABl-0Ajov8427.jpg" height= "101" />

The cycle of death.

While

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "http://s3.51cto.com/wyfs02/M02/73/85/wKiom1YADkPw2gBrAAB_5aHFPNw468.jpg" height= "266" />

For

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "http://s3.51cto.com/wyfs02/M00/73/83/wKioL1YAEIGg6NL3AAG50bC2Ylc257.jpg" height= "254" />

Case

3. Combined statement

4. Input statement

5. Output Statement print,printf

Loop control: Break,continue,next

Next, advance into the next line of processing!!

Array:

Legacy Arrays: Index starting from 1

Associative arrays

for (var in array), array is index

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "http://s3.51cto.com/wyfs02/M00/73/83/wKioL1YAEILAj9HOAAEY3LY3m2o161.jpg" height= "133" />

650) this.width=650; "title=" image "style=" border-top:0px;border-right:0px;border-bottom:0px;border-left:0px; " Border= "0" alt= "image" Src= "http://s3.51cto.com/wyfs02/M00/73/85/wKiom1YADkSisLdQAACGz1NS3po664.jpg" height= "70"/ >

This usage is very common and counts the number of different names in the same field

Built-in functions:

Length (string), string length

Split (target string, separated position, delimiter) delimited string

SUBSTR Fetch substring

September 15 awk Summary