AWK Tips

awk one-liner Tips and Tricks

Number of lines in a file
$awk ‘ END {print NR}’ file_name
 
Number of columns in each row of a file
$awk ‘ {print NF’} file_name

Print column1, column5 and column7 of a data file or output of any columns list
$awk ‘{print $1, $5, $7}’ data_file
$cat file_name |awk ‘{print $1 $5 $7}’
$ls –al |awk ‘{print $1, $5, $7}’ -- Prints file_permissions,size and date
 
Syntax of running an awk program
Awk ‘program’ input file(s)
 
List all files names whose file size greater than zero.
$ls –al |awk ‘$5 > 0 {print $9}’
 
List all files whose file size equal to 512bytes.
$ls –al |awk ‘$5 == 0 {print $9}’
 
print all lines
$awk ‘{print }’ file_name
$awk ‘{print 0}’ file_name
 
Sort the output of file and eliminate duplicate rows
$awk ‘{print $1, $5, $7}’ |sort –u
 
List all file names whose file size is greater than 512bytes and owner is "oracle"
$ls –al |awk ‘$3 == "oracle" && $5 > 512 {print $9}’

List all lines longer that 50 characters
$awk ‘length($0) > 50 ‘{print }’ file_name
 
List first two columns
$awk ‘{print $1, $2}’ file_name
 
Swap first two columns of a file and print
$awk ‘{temp = $1; $1 = $2; $2 = temp; print }’ file_name
List all file names whose owner could be either "ora" or "root"
$ls –al |awk ‘$3 == "ora" || $3 == "root" {print $9}’
 
List all the files whose owner is not "ora"
$ls –al |awk ‘$3 != "ora" {print $9}’
 
List all lines which has atlease one or more characters
$awk ‘NF > 0 {print }’ file_name
 
Replace first column as "ORACLE" in a data file
$awk ‘{$1 = "ORACLE"; print }’ data_file
 
Remove first column values in a data file
$awk ‘{$1 =""; print }’ data_file
 
Calculate total size of a directory in Mb
$ls –al |awk ‘{total +=$5};END {print "Total size: " total/1024/1024 " Mb"}’
 
Calculate total size of a directory including sub directories in Mb
$ls –lR |awk ‘{total +=$5};END {print "Total size: " total/1024/1024 " Mb"}’
 
Find largest file in a directory including sub directories
$ls –lR |awk ‘{print $5 "\t" $9}’ |sort –n |tail -1