AWK

AWK Structure


pattern {action}
BEGIN and END patterns in the AWK


BEGIN { print “BEGIN” }
{ print }
END   { print “END”  }

# cat textfile.txt 

Ashish 123

Ashi     456

Ash      789

A          000

# awk '{print $1}' textfile.txt 

Ashish

Ashi

Ash

A

# awk '{print $2}' textfile.txt 

123

456

789

000

# awk '{print $2,$1}' textfile.txt 

123 Ashish

456 Ashi

789 Ash

000 A

If the file is seperated with some delimeter, then we make use of -F for awk.

In the below example, the input file is using the pipe ( | ) as delimiter.

# cat textfile.txt 
Ashish|123
Ashi|456
Ash|789
A|000
Ashish|007


# awk -F\| '{print $1}' textfile.txt 
Ashish
Ashi
Ash
A
Ashish


# awk -F\| '{print $2}' textfile.txt 
123
456
789
000
007


# awk -F\| '{print $2,$1}' textfile.txt 
123 Ashish
456 Ashi
789 Ash
000 A
007 Ashish



# awk -F\| '$1=="Ashish"' textfile.txt 
Ashish|123
Ashish|007


# awk -F\| '$1=="Ashish"{print $1}' textfile.txt 
Ashish
Ashish


# awk -F\| '$1=="Ashish"{print $2}' textfile.txt 
123
007

To print the lines which does not contain the pattern Ashish:

# awk '!/Ashish/' textfile.txt 

Ashi|456

Ash|789

A|000

To print the records whose amount is greater then zero:

# awk -F\| '$2>0' textfile.txt 

Ashish|123

Ashi|456

Ash|789

Ashish|007

To print the Ashish record only if it the first record:

# awk 'NR==1 && /Ashish/' textfile.txt 

Ashish|123

To print all Ashish record whose amount is greater then zero:



# awk -F\| '/Ashish/ && $2>0' textfile.txt 
Ashish|123
Ashish|007

In some cases we don't know how many fields (columns) are there in the file, we can make use of special variable called NF (Number of fields).


we can print the last field using $NF and last before column as $(NF-1).

awk Variable	Meaning
FILENAME	Name of current input file
RS	Input record separator character (Default is new line)
OFS	Output field separator string (Blank is default)
ORS	Output record separator string (Default is new line)
NF	Number of input record
NR	Number of fields in input record
OFMT	Output format of number
FS	Field separator character (Blank & tab is default)