Linux Shell 检查程序是否正常退出

1 检查命令执行成功

echo $?

2 检测目录是否存在

test -d /user/local/bin
if [ "$?" -eq 0 ] # Check the return code
	then # The return code is zero
	echo '/usr/local/bin does exist'
else # The reurn code is NOT zero
	echo '/usr/local/bin does NOT exist'
fi
/usr/local/bin does NOT exist

3 方式2

if test -d /usr/local/bin
then    # The return code is zero
        echo '/usr/local/bin does exits'
else    # The return code is NOT zero
        echo '/usr/local/bin does NOT exit'
fi

4 方式3

if [ -d /usr/local/bin ]
then    # The reurn code is zero
        echo '/usr/local/bin does exist'
else    # The reurn code is NOT zero
        echo '/usr/local/bin does NOT exist'
fi