how to declare variable in perl

Shell Programming and Scripting
1

how can i declare variable in perl.

 for BLOCK in /sys/block/emcpow*
2

That's not even how you declare a variable in shell... I think you mean, how do you *-globbing in perl.

foreach( </sys/block/emcpow*> )
{
        system("blockdev --setra 16384 $_");
}

Just one thing to realize: system() runs a shell exactly like the shell the scripts I already showed you ran in.

So you are not running perl instead of shell. You're running lots and lots of shells, with a tiny topping of pointless perl. (Sorry, it's a peeve of mine.)

3

please check below code is it true.


foreach( </sys/block/emcpow*> )
{

 system("echo "noop"", "$_");
}

---------- Post updated at 04:55 PM ---------- Previous update was at 04:53 PM ----------

Another code in perl is correct please confirm

foreach( </sys/block/emcpow*> )
{
        blockdev --setra 16384 $_;
}

---------- Post updated at 05:24 PM ---------- Previous update was at 04:55 PM ----------

sir it is giving error

BLKRASET: Inappropriate ioctl for device when running below perl code.

---------- Post updated at 05:37 PM ---------- Previous update was at 05:24 PM ----------

Please correct this

        system("echo "noop" > $_");
4

system() takes one parameter, not two or three or four.

You can't put quotes in quotes like that. If you must, escape them like \".

I repeat. By doing this "in perl", you are actually doing this in lots and lots of shells. Every time you run system(), you are running /bin/sh. There is no purpose to using perl here.