UNIX for Dummies Questions & Answers

Hi Gurus,

I am tryin to get the nth argument/parameter ( n being calculated in runtime).
I want to assign tghis value to a variable say myvar. How do i do it? I am struggling to get proper escape chars in place.

e.g. Say my script name is myscript.sh
I will run the script by typing $myscript.sh abc def ghi
In the script i have a variable n which wil indicate which parameter to pic up and myvar should contain this parameter.

Thanks in advance.

Code:

eval var=\$${n}

Thank You!

The eval var=\$${n} only works for n <= 9. For arbitrary values of n, you'll have to do something more elaborate. Perhaps this inefficient bit of code will help. This uses ksh syntax, so bourne shell will not work. Bash will though:

#!/bin/ksh

n=5
i=1
while [ -n "$1" ] ; do
echo Arg is: $1 i is $i
arguments[$i]=$1; shift
echo arguments array entry $i set to ${arguments[$i]}
let i=i+1
done
echo "I want argument $n. It is: ${arguments[$n]}."

I would expect it to work for n>=10 too...

Code:

$ set q w e r t y u i o p a s d f
$ n=11
$ eval echo \${$n}
a

I guess we can doit by:
1. shift for multiples of ten
or
2. Assign the arguments' list ($*) and using cut (though might fail in few cases)

Any better alternatives UNIX gurus?

From Ygor's post:

Code:

eval var=\${$n}

or even

Code:

eval var=\${${n}}