vangie · October 10, 2015 15:07
diff --git a/bash_default_value.sh b/bash_default_value.sh
 #!/bin/bash

 #直观当繁琐的写法
 if [ ! $1 ]; then
       $1='default'
 fi

 #当变量a为null时则var=b
 var=${a-b}

 #当变量a为null且为空字符串时则var=b
 var=${a:-b}
	#!/bin/bash

	#直观当繁琐的写法
	if [ ! $1 ]; then
	$1='default'
	fi

	#当变量a为null时则var=b
	var=${a-b}

	#当变量a为null且为空字符串时则var=b
	var=${a:-b}