if ! mkdir语言 - p $APPLICATION_DIRECTORY/conf

Question

谁能告诉我下面的shell命令是做什么的？

if ! mkdir -p $APPLICATION_DIRECTORY/conf

Answer 1

mkdir -p "$APPLICATION_DIRECTORY/conf"尝试创建命名目录，在此过程中创建任何缺少的父目录。像每个命令一样，它有一个整数退出状态，其中 0 表示目录已成功创建，非零值表示某种错误。

if命令测试其命令的退出状态，而不是像大多数其他编程语言那样测试布尔值。!运算符否定退出状态：非零退出状态转换为 0，退出状态 0 转换为 1。

换句话说，

if ! mkdir -p "$APPLICATION_DIRECTORY/conf"; then
echo "There was an error creating the directory"
else
echo "The directory was successfully created"
fi

Answer 2

你也可以使用直接逻辑(更容易理解(：如果mkdir -p ...

例：

if mkdir -p "$APPLICATION_DIRECTORY/conf"; then 
echo "The directory was successfully created"
else 
echo "There was an error creating the directory"
fi