Linux Shell Programming Example Tutorial

• awk [-field-separator] 'commands' input-file(s)

Basic mode

• awk -F':' ...

Use # to separate

• awk '{print $0}' a.txt

Print all

• ##awk '{print $1,$3}' a.txt

Print 1st , 3 columns

• awk 'BEGIN{print "0"}{print $1}' a.txt

The first line prints 0

• awk '{print $1}END{print "0"}' a.txt

The last line prints 0

• awk '$1 == "0" {print $0}' a.txt

The row where the first column is equal to 0

• awk '$1!="0" {print $0}' a.txt

The first column is not equal to 0

• awk '$1<=$2'

The rows where the first column is less than or equal to the second column

• awk '$0!~/0 /' a.txt

Regular match all rows whose columns do not contain 0

• awk '$1~/(12|(34)/ ' a.txt

Regular match the first column matching 12 or 34 rows

• awk 'if($1>1 && $2< ;1) {print $1} a.txt

The first column of the row where the first column is greater than 1 and the second column is less than 1

• awk 'if($1>1 || $2<1) {print $2} a.txt

The first column is greater than 1 or the second column is less than 1 Two columns

• awk '{print NF RS NR}' a.txt

Continuously print the number of record columns, record separator, and read Number of records

• awk 'NR==FNR {print $1} NR>FNR {print $2}' a.txt b.txt

Print the first column of the first file and the second column of the second file

• awk '{$1=$1*2; print $1}' a.txt

Modify numerical value printing

##awk 'BEGIN{LAST=0} {if($1>LAST) print $1; LAST=$1}'
Compare one by one and print the increasing sequence

awk '{total+=$1} END {print total}' a.txt
Statistical column value

awk '{printf "%c", $1}' a.txt
Formatted output

awk '{print match($1, "1")}' a.txt
Print the position of the first 1 in the first column , no printing 0

awk '{gsub(/ab/,"cd",$1); print $0}' a.txt
First column string replacement

awk '{MAP[$1]=$2} END {for(I in MAP){print I, MAP[I]} }' a. txt
Dictionary storage and retrieval

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