BASH Programming

[Rory Glenn Pascua]

Can anyone help me understand the script below?

#!/bin/bash
if [ "foo" = "foo" ]; then
echo expression evaluated as true
fi

I'm trying to understand why there's space between the square brackets and "foo". Also I want to know if I can use curly brackets or parentheses instead of the square brackets. Thanks in advance.

 

[ehansen]

Basically, its the syntax of Bash. If you try to remove the spaces, the if statement will error out and your script just won't run. As for your other question, no, you cannot replace the syntax of the language. If you want to do that it'd probably be easier just to write the script into an actual programming language instead of a scripting language.

 

[Rory Glenn Pascua]

Script

Thanks

 

[tux.think]

The [ in bash programming is a command in itself which basically tests the condition and returns true or false. Hence the if and the [ have to be seperated by a space.
In case you do not want to use the [ you will have to use the command test as follows

if(test "foo" = "foo) then
echo "strings match"
fi

In this case there is no need for a space in between if and the (.

So basically the command "test" and [ are one and the same.

 

[Rory Glenn Pascua]

Script

Thanks Tux

 

[Rory Glenn Pascua]

TUX: it works but now I want to know why you don't need a space between "if" and "("

Thanks

 

[Rory Glenn Pascua]

Got it now.... thanks.