Shell Programming and Scripting

There is nothing wrong but the way you want to put condition.I guess you want to pass exactly two parameters and check if the second one is P Q or D and then show success else improper usage.
Try this code or the one i posted yesterday

Code:

if [[ $# -eq 2 ]] && [[ $2 = "P" || $2 = "Q" || $2 = "D" ]] then
echo "Success"
exit 0; 
else
echo "Improper usage"
exit 1; 
fi

thanks dhruv for finding time ..It work the way i want but actually i need the previous code mention by AHAT yesterday.

I run that code but see the Out Put :
$ ./t1.sh scr P
Improper Usage
$ ./t1.sh scr D
Improper Usage
$ ./t1.sh scr Q
Improper Usage

But according to the yesterday code : when $# less then 2 and $2 is not either of P,Q,D it should print Improper use !!Right ??
But even if i am providing right argument why it is showing "Improper Use "
I am looking at the BUG but could not find ! can you tell me ?

if [[ $# -eq 2 ]] && [[ $2 != "P" || $2 != "Q" || $2 != "D" ]] then
echo "Failure "
exit 0
else
echo "Success usage"
exit 1
fi

Input : t1.sh scr P
Out put : Failure

Input t1.sh scr Q
output: Failure


Any clue ?

Ok Try with this

Code:

if [[ $# -eq 2 ]] && ! [[ "$2" = "P" || "$2" = "Q" || "$2" = "D" ]] then
echo "Failure "
exit 0
else
echo "Success usage"
exit 1
fi

Clever & Great ! worked as expected

! Outside the bracket work but when it was with the inner condition not worked. any reason you found for that ?.
Although seems simple but one can make this mistake and may be trapped for a time.
thanks a lot thanks for the help.

is logically incorrect. It will always equate to true because of '||'. It means $2 is not equal to P or $2 is not equal to Q or $2 is not equal to D. If $2 is P then $2 not equal to Q,D is true, so on....

&& is required whenever multiple != conditions are to be checked.

Thank you vish, for pointing out my logical error. Seems like I am having off day yesterday as well.