On 10 December 2010 14:22, Niall O Broin <niall at magicgoeshere.com> wrote:
> On 10 Dec 2010, at 14:15, Braun Brelin wrote:
>>> Does anyone know the reason why I have to quote strings when testing them
>> like so?
>>>> s1="foo"
>>>> if [ -n "$s1" ]; then
>> echo blah
>> fi
>>>> i.e. why the "$s1" in the test expression? Anyone know the answer?
>> You don't "have" to do it, but if you don't, you'll get an error when $1 isn't set because
>> if [ -n ] ; then
>> is syntactically incorrect
>> while
>> if [ -n "" ]; then
>>> is not.
>
Another reason in general for quoting variables in bash is having more
than one word in your variable. In other words if your variable
contains spaces, it will be seen as separate args.
EXAMPLE="purple monkey dishwasher"
perl -e 'print scalar(@ARGV)' $EXAMPLE
perl -e 'print scalar(@ARGV)' "$EXAMPLE"
Sometimes it's ok for them to be split, but unless you explicitly want
them to be seen as separate arguments, it's easier to just quote them
and not have to think about it.
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