UNIX for Dummies Questions & Answers

Hi
I want to know what is the difference between $var and ${var}.
I saw in few of the scripts examples.Somewhere people use $var and somewhere ${var}.
Is there any difference between two ?

Thanks

In principle they are the same, but one should use ${var} if $var is immediately followed by an alphanumerical character or an underscore (_) . The curly brackets are also necessary if you want to refer to more than nine positional parameters, e.g. ${10)

${var} is usefull when you want to include the variable in some echo output (in shell, in perl it can be print), that needs to be followed immediately by some string. Here is an example:
This wont work:

Code:

echo "$varsomething"

But this will:

Code:

echo "${var}something"

So basically saying, {} are indicating borders of variable's name.

Thanks Scrutinizer and bartus11's for quick and informational reply.

Kudos

They are generally interchangable, however the curly braces disambiguate the variable, so for example:

Code:

var="to the "
echo "Hello$varworld"
echo "Hello${var}world"

Would return two different responses from the two echo statements as the first would attempt to echo the contents of the variable "varworld" which doesnt exist and is therefore empty. The second echo will work as designed.

I hope this makes things clearer.