Programming Forums - Which test syntax to use?

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aznluvsmc

Dec 29th, 2005 2:21 PM

Which test syntax to use?

I found out that you can use [ test-condition ] or [[ test-condition ]] in shell scripts . To me the [[ test-condition ]] syntax seems to resemble other programming lanuage syntax by support && and || logical operators. Is one syntax preferred over the other?

jim mcnamara

Jan 3rd, 2006 9:10 AM

There is no "preference". [[ ]] is required for tests that support booleans like || and &&.

I am assuming you mean either bash or ksh here.

a thing

Jan 3rd, 2006 4:06 PM

I've used single brackets with || and &&.

jim mcnamara

Jan 4th, 2006 12:55 PM

Quote:

Originally Posted by a thing

I've used single brackets with || and &&.

Depends on which shell you use - ksh requires it.

You can also use -o

if [ $a -eq 0 -o $b -eq 0 ] ; then

which does not require [[ ]]

aznluvsmc

Jan 17th, 2006 6:00 PM

I personally find using || and && with [[ ]] to be a more "natural way" of testing a condition as opposed to -o and -a using [ ].

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