awk of Linux commands

Awk is a powerful text analysis tool that reads the file line-by-row, using spaces as the default delimiter to slice each row, and then perform various analytical processing of the cut.

awk command form:

awk [-F |-f |-v] ' begin{}//{command1;command2; COMMANDN} end{} ' file

[-F |-f |-V]: Large parameter,-F specify delimiter,-F call script,-v define Variable

': Reference code block

BEGIN: Initializes the code block, initializing the code before processing on each line, (primarily referencing global variables in the script, setting the FS delimiter)

: Match style, can be a string or regular expression

{}: Command block of code containing one or more commands

;: Multiple commands are delimited with semicolons

End: The end code block, the code block executed after each row is processed, primarily for final calculation or output end summary information.

The arithmetic operations that AWK supports:

+  -   *  /  ^  %  ++ -- += -= *=  /= %=

awk built-in variables:

The whole thing is going forward

$n nth field per row, N cannot be 0

NF Field number Variable

NR record number per row, multi-file processing is record increment

FNR record number per row, multi-file processing is not incremented, each file starts from 1

Defining delimiters when FS begin

The record delimiter entered by the RS, which defaults to line breaks

OFS output field delimiter, default is space

ORS output record delimiter, default is line break

Sample file Emp_names

$ cat Emp_names 46013     DURHAM jeff      mobile      al46015     Steen bill       MOBILE      al46017     FELDMAN evan     mobile     AL46018      SWIM steve       unknown    al46019      Bogue robert     phoenix    az46021     JUNE micah       phoenix    az46022     KANE sheryl      unknown    ar46024     WOOD WILLIAM      muncie     in46026     Fergus sarah      muncie     in46027     BUCK sarah       muncie     in46029     TUTTLE bob        muncie     in

$ Awk ' {print $} ' emp_names    #打印文件emp_names中的所有字段46013     DURHAM JEFF      MOBILE     AL46015     Steen BILL       MOBILE     AL46017     FELDMAN EVAN     MOBILE     AL46018     SWIM STEVE       UNKNOWN     AL46019 Bogue ROBERT Phoenix    AZ46021     JUNE Micah       Phoenix    AZ46022     KANE SHERYL      UNKNOWN    AR46024     WOOD WILLIAM     MUNCIE     IN46026     Fergus Sarah     MUNCIE     IN46027     BUCK Sarah       MUNCIE     IN46029     TUTTLE BOB       MUNCIE     in$ awk ' {print $1,$2,$3,$4,$5} ' emp_names   #打印文件emp_names中多个字段46013 DURHAM JEFF Mobile AL46015 Steen BILL Mobile AL46017 FELDMAN EVAN Mobile AL46018 SWIM STEVE UNKNOWN AL46019 bogue ROBERT PHOENIX AZ460 JUNE Micah PHOENIX AZ46022 KANE SHERYL UNKNOWN AR46024 WOOD WILLIAM MUNCIE IN46026 Fergus SARAH MUNCIE IN46027 BUCK SAR AH MUNCIE IN46029 TUTTLE BOB MUNCIE in

$ Awk '/al|az/{print $3,$2,$5} ' emp_names multiple fields for #打印文件emp_names中匹配AL,  az style Jeff DURHAM Albill Steen Alevan FELDMAN ALS TEVE SWIM alrobert bogue azmicah JUNE az$ awk ' $5~/ar/' emp_names #在第5个字段中匹配样式, no print fields are specified, all fields are printed 46022   &N Bsp KANE sheryl      unknown    ar$ awk ' $5!~/ar/' Emp_names #在第5个字段中匹配样式, Print out all rows that do not match (no print fields are specified, all fields are printed) 46013     DURHAM jeff      mobile      al46015     Steen bill       MOBILE      al46017     FELDMAN evan     mobile      al46018     SWIM steve       unknown    al46019     Bogue robert     phoenix    AZ46021      JUNE micah       Phoenix  &nbsP az46024     WOOD william     muncie     IN46026      Fergus sarah     muncie     in46027      BUCK sarah       muncie     in46029      TUTTLE bob       muncie     in$ awk ' $5~/ar/{print $; print $ 2; Print $ ' emp_names #将一行中多个字段分行打印46022KANESHERYL

$ Awk ' {print $ | "Sort >/tmp/filez"} ' emp_names #将文件emp_names中字段排序, redirect to/tmp/filez file in $ Cat/tmp/filez 46011     TUTTLE bob       muncie     in46012     Steen bill       mobile     AL46013     DURHAM jeff      mobile     al46017     FELDMAN evan     mobile     al46018     BOGUE ROBERT      phoenix    az46019     SWIM steve        unknown    al46021     JUNE micah        phoenix    az46022     KANE sheryl      UNKNOWN     ar46027     BUCK SARAH   &NBsp;   muncie     in46030     FERGUS SARAH      muncie     in46045     WOOD william     MUNCIE      in

$ awk-f ":" ' {print $} '/etc/passwd   #/etc/passwd is the system comes with the file each line is used: delimited characters, so you need to specify the delimiter can also use  awk ' {fs= ': '} {print $} '/etc /PASSWD  So the result is the same rootdaemonbinsyssyncgamesmanlpmailnews ...

$ cat Awk.list begin{fs= ":"}{print $1}$ awk-f awk.list/etc/passwd  #使用-F invoke awk script ROOTDAEMONBINSYSSYNCGAMESMANLP

$ awk ' {fs= ': '} {ofs= '-"}{print $1,$3} '/etc/passwd #指定输出字段分隔符root: x:0:0:root:/root:/bin/ bash-daemon-1bin-2sys-3sync-4games-5man-6lp-7$ awk-f ":" ' {print ' user_name: "$," \nnumber: "$ $} '/etc/passwd  # Output user_name:root Number:0user_name:daemon number:1user_name:bin number:2user_name:sys Number:3user_nam in the format and content you want E:sync Number:4user_name:games Number:5

Sample file contents $ cat Inventory hammers57.99drills229.99punches73.59drifts24.09bits551.19saws12314.99nails800.19screws80.29brads100.24

$ Awk ' BEGIN {print "Item\tquantity\tprice\ttotal"} {x=x+ ($2*$3)} {print "\ T" $ "\t\t" $ "T" $2*$3} END {print "Total Val UE of Inventory: "x} ' inventoryitemquantitypricetotal  # Begin keyword hammers57.9939.95drills229.9959.98punches73.5925.13drifts24.098.18bits551.1965.45saws12314.991843.77nails800.1915 2screws80.2923.2brads100.2424total value of inventory:2241.66     #END关键字 x Last value

AWK itself is a programming language, with support for IF statements, looping statements, and programming in C-like languages.



awk of Linux commands