[SOLVED] Counting variables in bash script

[jf22901]

Hi all.

If I read in variables entered by the user, how can I check to make sure the correct number of variables were entered? For example, after reading in a data file and making it into an array, I have:

echo "To check the data, enter the first element number, last element number and step size as x y z:"
read x y z

It then goes on to start a loop, but what I would like now (before the loop) is a check to see if three variables have been entered, before the rest of the script continues.

I've tried specifying the variables as $1, $2 and $3, but if I echo $#, the value comes out as zero, so it's obviously not working.

Can anyone please offer any help?

Thanks in advance,

Jack

[barriehie]

Since you're reading x y z wouldn't you have to use $x $y and $z? $1 $2 and $3 would be if they're entered on the command line with the script name.

HTH

[jf22901]

Hi barriehie

Do you mean like this (for example):

#!/bin/bash
echo "Enter the first element number, last element number and step size as x y z:"
read $x $y $z
echo "$#"

I have tried this method too, but it still won't 'count' the number of variables. I'm sure it's something simple, but I can't fathom it out. (In my defence, I did only learn bash scripting last week!)

[barriehie]

Hi barriehie

Do you mean like this (for example):

#!/bin/bash
echo "Enter the first element number, last element number and step size as x y z:"
read $x $y $z
echo "$#"

I have tried this method too, but it still won't 'count' the number of variables. I'm sure it's something simple, but I can't fathom it out. (In my defence, I did only learn bash scripting last week!)

More like:

read x y z

Since you're not entering anything on the CLI after the script name then $# will be 0; $0 will contain the script name.

To test whether or not x, y, and z were all entered you'll have to test them against being NULL.

./scriptname value1 value2 value3

$0 = ./scriptname
$1 = value1
$2 = value2
$3 = value3
etc., etc., etc.

[jf22901]

Thanks barriehie.

I have now added the following, which tests to make sure neither x, y nor z are null.:

if [ -z "$x" ] || [ -z "$y" ] || [ -z "$z" ]; then
echo "Error: Run script again and enter search parameters correctly" && exit
fi

It seems to be working, so I'll leave it at that!

[barriehie]

Glad you got it! Another [Solved].

[barriehie]

So is this thread solved???

[jf22901]

So is this thread solved???

It is indeed! Am I meant to click on something, or mark it as solved??

Jack

[barriehie]

It is indeed! Am I meant to click on something, or mark it as solved??

Jack

If you would, makes it easier for the next ?. I think you have to either edit the title to mark it solved or it's under thread tools.

[jf22901]

Done.

Thanks for all your help!