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Cat Command and Blank Lines

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# 1  
Old 02-26-2010
Cat Command and Blank Lines
Hi All,

I was testing for blank lines and I want to use the cat command only

Code:
for groupline in `cat /home/test/group`
do
         if [ -z $groupline ]
    then
        echo "blank found"
    fi 
done

I want to check if the current line read is a blank line.

I have tested with $groupline="\n" , "\r\n" but no use.

Any ideas ?
Last edited by pludi; 02-26-2010 at 06:49 AM.. Reason: code tags
# 2  
Old 02-26-2010
MySQL
Code:
$groupline=  /^$/ ;

It will match only blank line
# 3  
Old 02-26-2010
Have you tried with grep "^$"?
# 4  
Old 02-26-2010
Quote:
Originally Posted by datkan
Hi All,

I was testing for blank lines and I want to use the cat command only
Why? Homework?

The cat command is used to concatenate and display files.

It is mostly unnecessary in conjunction with other commands.
# 5  
Old 02-26-2010
Actually when using the cat command with the for loop it is not at all giving the blank lines

I am having the file "group" with some of the lines as blank also.

I have tried the following code
Code:
for groupline in `cat /home/thillaiselvan/group`
do
        echo $groupline
done

the output I am getting is as follows when executing the above script
hai
hello

So the cat command itself in the above context is not giving the blank lines
# 6  
Old 02-26-2010
Thts right Thillai....

There is an existing code ....I have posted a simplified example here....so I cant change the way the file is read....Is there a way around to test ?

And Franklin , Its not homework Smilie
# 7  
Old 02-26-2010
Using CAT we cannot achieve this
So we can do in this way ( if you prefers )
Code:
while read line
do
        echo -e "$line \n"
         if [ -z $line ]
    then
        echo "blank found"
    fi
done <filename
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