Validate User Input is 16bit signed integer

[mudasir]

Assalam-o-alaikum,

I am making a shell script in which i need user to input a Signed 16bit Integer as arguments to the script.
The script will take 6 arguments which all should be Signed 16bit integer.

I would like to know how can i verify that the value that user has input is a Signed 16bit integer. I need to verify $1 $2 $3 $4 $5 $6.

Looking for a positive and quick reply.

[LinuxFreaK]

Dear mudasir,
Hello,

You can use something like this ...

Code: Select all

if [ $# -ne 16 ]
then
    echo 1>&2 Usage: $0
    exit 127
fi

Best Regards.

[lambda]

just check if each number is between -32768 and 32767.

[mudasir]

Assalam-o-alaikum,

Thanks allot for the help, i have completed the user input validation function. Now i am stuck in another mathematical error. Please help me out in this.

my script takes 6 parameters as input
./<script name> X1 Y1 Z1 X2 Y2 Z3

then script perform some calculation on these values, where i am stuck is that, if Y1 value or any other value has a "-" sign with it, shell gives me an error

DIV=`expr $Y2 - $Y1`
T=`expr -$Y1 / $DIV` &> /dev/null

this is where i get an error, error is
"expr: non-numeric argument"

when script run in debug mode i see
++ expr 2 - -2
+ DIV=4
++ expr --2 / 4

the double "--" sign is creating problem.

The formula through which i have to do calculation has a "-" sign so how to overcome this issue.

Thanks in advance.

[lambda]

why don't you explain the mathematics behind the calculation? what does it mean for y1 to be negative in the mathematical equation?

[azfar]

you are trying to minus a negative integer from another integer and then divide it by another integer?

if so then use the + operator for subtraction operation too, it will give you the right answer.