4 years ago
source link: http://blog.51cto.com/lythjq/2073516
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变量设置方式说明示例${#变量}变量的长度A='Hello world!'echo ${#A}结果:12${变量:-word}如果变量为空或未定义,则变量展开为”word”;否则,展开为变量的值A='Hello world!'echo ${A:-OK}结果:Hello wold!unset A或 A=’’echo ${A:-OK}结果:OK${变量:+word}如果

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