how to read more than ten arguments of user input in a script

new_2_unix · 11-19-2007, 11:50 AM

hi,

in a shell script we can refer to the arguments entered by the user on the command line simply with a $1, $2, $3 ... representing the first, second, third ... arguments entered by the user.

however, this works only if there are less than 10 arguments, because for argument 10 - the script interprets $10 as the value that $1 has and then append it with a 0.

in other words, if have a script which simply does an echo of $1, $2 and so on... the output would be like this

Code:

$./myscript foo1 bar2 ... ... arg9 arg10
> Argument1: foo1
> Argument2: bar2
...
...
> Argument10: foo10

Is there a way to tell the shell to interpret '10' as one number instead of evaluating $1 and then appending it with a 0? any guidance will be helpful. thanks!

kaz2100 · 11-19-2007, 11:52 AM

Hya,

Is shift what you want??

cheers

colucix · 11-19-2007, 12:05 PM

kaz2100 is right, but you can also enclose the positional parameter in brackets

Code:

${10}

new_2_unix · 11-19-2007, 12:42 PM

i tried to do this with shift, it will work but then i also need a for loop that keeps on shifting the arguments to the left one by one (may be i'm wrong), i tried doing this but for some reason it wasn't working out properly. i could read the 10th argument, but then it kept on repeating it for the arguments after that, which means something is wrong with my loop. but the ${10} solves my problem completely, so i'll use that for now... but will try the shift later on. thanks to both of you!

new_2_unix · 11-19-2007, 01:29 PM

on one system the ${10} works, but on another it results in a "bad substitution" error... is there a way to resolve this discrepancy? thanks!

colucix · 11-19-2007, 03:18 PM

Quote:

Originally Posted by new_2_unix

on one system the ${10} works, but on another it results in a "bad substitution" error... is there a way to resolve this discrepancy? thanks!

Yes, I remember it did not work - for example - in the Bourne shell /bin/sh on Unix systems and the only way to parse a number of arguments greater than 9 was by means of the shift command. You can try a for loop or even better

Code:

until [ -z "$1" ] ; do
   echo "$1"
   shift
done

I hope this helps.