Can anyone help me how do i find the size of a file in bytes.

I know -s <filename> returns the size in bytes but how do i get that in a variable.

Also, how do i equate a variable to a newline character in shell program.

For eg:

if [ "$line" == "\n" ]

Somehow the above statement doesnt work when i try to check for the newline character in my program.

Thanks.

i don't want to use sed, awk or perl in my shell script. so, please suggest an altenative.

First, test -s <file name> doesn't return the file size. It returns true if the file exists and the size is greater than zero.

a way is to look at the 5th field of a long listing:

if [ -s my.file ]
then
myvar=`ls -l my.file|awk ' { print $5 } '`
echo $myvar
fi

Regarding your second question, how about using test's -z option? This returns true if the length of line is zero:

read line
if [ -z $line ]
then
echo "null"
fi

the closest you can get, AFAIK, without using sed/awk/perl is use wc -c

eg wc -c filename.txt

output:

4096 filename.txt