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Shell Programming and Scripting

op is invalid

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# 1  
Old 08-29-2009
op is invalid
In the following code

Code:
a=
[ -n $a ]
echo $?
[ -z $a ]
echo $?

Why the op is

Quote:
0
0
# 2  
Old 08-29-2009
Quote the variable and you'll get the correct result.
# 3  
Old 08-29-2009
The -n test requires that the string be quoted within the test brackets. Other test operators, or using no operator (implied -n), will generally work as you would expect without quoted strings. But, to be safe, it is generally recommended that you always quote your strings when testing.

Code:
a=
[ -n $a ]
echo $?
[ $a ]
echo $?

Output:
Code:
0
1

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