Practical no-8: Write a awk script that uses all its Features

Practical no-8: Write a awk script that uses all its Features

As an example of using numeric expressions, look at the following script that counts the number of blank

lines in a file:

#!/bin/sh

for i in $@ ;

do

    if [ -f $i ] ; then

        echo $i

        awk ' /^ *$/ { x=x+1 ; print x ; }' $i

    else

        echo "ERROR: $i not a file." >&2

    fi

done

In the awk command, you increment the variable x and print it each time a blank line is encountered.

Because a new instance of the awk command runs for each file, the count is unique of each file.

Consider the file urls.txt, which contains four blank lines:

$ cat urls.txt

http://www.cusa.berkeley.edu/~ranga

http://www.cisco.com

ftp://prep.ai.mit.edu/pub/gnu/

ftp://ftp.redhat.com/

http://www.yahoo.com/index.html

ranga@kanchi:/home/ranga/pub

ranga@soda:/home/ranga/docs/book/ch01.doc

For urls.txt, the output of this script looks like the following:

urls.txt

1

2

3

4