shell笔记

1. 检测命令是否存在

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if ! hash some_exec 2>/dev/null;then      echo "'some_exec' was not found in PATH"  fi  ​  if ! type some_exec >/dev/null;then      echo "'some_exec' was not found in PATH"  fi

不使用which ，which不是内建命令，可能不同的平台实现不一样。 

2. 检测元素是否在数组里

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arr=(apple,banana,orange) exist=0 for i in $arr;do   if [[ $i == "orange"]];then     exist=1   fi done if [[ $exist == "1"]];then   echo "exist" fi