Shell Programming and Scripting

If your script name is test.sh and say $2 turns out to be trust,

then $0 $2 is equivalent to

test.sh trust

And since you dont have more than one argument, it will not be recursive.

Vino

When a script can recurse at most one time, do you still call it recursive? I'm not sure either. We use UUOC to mean "unnecessary use of cat". Maybe we need UUOR to go with it? How about this alternative..,

Code:

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

well im not talking about recursivity!
i wish to know how does this work?

vino has answered your question, correctly as far as I can see. He mentioned that the script is using recursion. And since you used the present tense, wish, it is apparently the recursion that is still confusing you.

C|[anti-trust],

In

Code:

cp $1 $2
$0 $2

,

Code:

$0 $2

is not part of the cp command

Code:

cp $1 $2

This code will give the same results with an echo'ed string.

Code:

cp $1 $2
echo " cp $1 to $2"
$0 $2

Vino

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

Concur with everyone's comment on this part of the code.
Here is mine.

The script is always taking $1 through out and ignoring $2.
I feel 'if' construct is not at all needed there. The code in 'else'
part simply works.

Only thing 'if' part doing is ,
if the script is provided with 2 arguments as files,
override the 2nd file contents with first file.
the second line $0 $2 is going recursive second and last time
leading that to else part.


"Complex way of doing things"