shell script - awk tips

shell script - awk tips

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

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

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 file names whose owner could be either "oracle" or "root"
$ls –al |awk ‘$3 == "oracle" || $3 == "root" {print $9}’

list all the files whose owner is not "oracle
$ls –al |awk ‘$3 != "oracle" {print $9}’

List all lines which has atlease one or more characters
$awk ‘NF > 0 {print }’ file_name

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

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