UNIX for Dummies Questions & Answers

what glenn has said is right.. not {$num1} it should be ${num1} .. sorry for typo mistake birdi...

You must export the shell variables to the environment of subsequently executed commands.
export num1
export num2

The result will always be blank if you just execute the script as a subshell. To use num3 in the current shell, you must source the file. Glenn Arndt made reference to this when he told you to execute the file as " . lazyadd2 ".



Maybe this will help. Is this what you are trying to do?

Code:

$ cat lazyadd2
#!/bin/bash
#I have added the she-bang script above as I felt that this would be a good idea.
#The script takes in 2 arguments that are added together
num3=`expr $num1 + $num2`
echo $num3


$ lazyadd2
expr: syntax error

The script doesn't have a value for num1 or num2 yet. I will now set a value for num1 and num2.

Code:

$ num1=1
$ num2=2
$ lazyadd2
expr: syntax error

Oops! Forgot to export them to the subshell environments.

Code:

$ export num1 num2
$ lazyadd2
3
$ echo $num3

Now the script works... but the variable num3 is still undefined. But if I source the file... .

Code:

$ . lazyadd2
3
$ echo $num3
3

I just thought that I should say that, with the above advice, the script DID work (I believe that Glenn Arndt's observation - that I should use ${}$ syntax not {$$} syntax - was where I was going wrong).

Also, thanks for the advice!