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Maciej Kazulak wrote: |
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> That's how bash evaluates logic expressions. There's even a fancy word |
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> for it i think. Point is it will execute commands only to the point |
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> where it can determine the logic result. |
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The fancy word for it would probably be short circuit evaluation: |
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http://en.wikipedia.org/wiki/Short-circuit_evaluation |
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When placing code in a boolean expression it is critical to understand |
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whether the boolean operator will be evaluated in a short-circuit |
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fashion in any language. |
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I'm not aware of any language that works this way, but potentially you |
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could even have out-of-order boolean evaluation (ie echo "hello" && |
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false does nothing) in a very well optimized language. |
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Using && in this way is technically a bit of a hack - the && operator |
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was intended to evaluate a boolean expression and not as a replacement |
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for "if". That doesn't stop 99.9999999% of shell scripters from using |
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it, however. It is less of a hack than writing the equivalent of 30 |
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lines of code inside a for(<gobs of code> ; <gobs of code> ; <gobs of |
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code>); statement in C. :) |
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