Shell Programming and Scripting

may i know what

Code:

cp $1 $2
    $0 $2

does?

Did you come up with this ?

Code:

cp $1 $2
    $0 $2

If you are trying to provide multiple arguments for cp, this is what man cp has to say..

Code:

DESCRIPTION
       Copy SOURCE to DEST, or multiple SOURCE(s) to DIRECTORY.

Keeping your command in tune with the man cp, we probably might have the following:

Code:

cp $1 $0 $2

which is self explanatory as per the man page.

Hopefully , this is what you were looking for.

Vino

well, i read in a book,

Code:

if [ $# -eq 2 ]; then
	cp $1 $2
	$0 $2
else
	tmp=`cat $1 | wc -l`
	echo $tmp
	while [ $tmp -ne 0 ] ; do
		echo `head -$tmp $1 | tail +$tmp` >> $1.tmp
		tmp=$(($tmp -1))
	done
	mv $1.tmp $1
fi

but i cant figure out how this

Code:

cp $1 $2
	$0 $2

could affect the script

That looks better.

Code:

if [ $# -eq 2 ]; then
	cp $1 $2
	$0 $2
else

Here's my analysis.

If you have 2 command line arguments provided by the user, then make argument 2 the same as argument 1.

And after you are done with that,

execute the script with $2 as an argument. In the shell scripting world, $0 holds the name of the script. So basically, you call the script with the value held in $2.

Let me know if you dont understand.

Vino

hmm so it is a recursivity script
thanks

Not a recursive one. I made a mistake in my explanation.

The point is..

If you have two arguments, then make arg1 and arg2 the same.

Else, find the numbers of lines in $1 and carry on ..

Vino

but my question is what does $0 $2 below the cp command do?