Programming Forums > Script Programming > Bash / Shell Scripting

aznluvsmc · Dec 29th, 2005, 2:21 PM

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

(Toggle Plain Text)

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 [ ].

Dec 29th, 2005, 2:21 PM	#1
aznluvsmc Hobbyist Programmer Join Date: Aug 2005 Posts: 137 Rep Power: 4	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?

Jan 3rd, 2006, 4:06 PM	#3
a thing Unverified User Join Date: Aug 2005 Location: none Posts: 146 Rep Power: 0	I've used single brackets with \|\| and &&. __________________ Warning: My posts may change (dramatically) within the first 15 minutes they're posted. Got 'Nux?�GNU/Linux and other free software support. It's GNU/Linux, not just Linux.

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Jan 3rd, 2006, 9:10 AM	#2
jim mcnamara Hobbyist Programmer Join Date: Jun 2005 Location: New Mexico Posts: 228 Rep Power: 4	There is no "preference". [[ ]] is required for tests that support booleans like \|\| and &&. I am assuming you mean either bash or ksh here.

Jan 17th, 2006, 6:00 PM	#5
aznluvsmc Hobbyist Programmer Join Date: Aug 2005 Posts: 137 Rep Power: 4	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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Programming Forums > Script Programming > Bash / Shell Scripting

Which test syntax to use?