${1:?}没有参数就报错return
#!bin/bash
#file name: test1.sh
bar=${1:?param empty}
echo $bar
- 执行
bash test1.sh，报错
test1.sh: line 3: 1: param empty
- 执行
bash test1.sh hi，输出
hi
${1:-}没有则给默认值
#!bin/bash
#file name: test2.sh
bar1=${1:-}
echo bar1:[$bar1]
bar2=${1:-default value}
echo bar2:[$bar2]
- 执行
bash test2.sh，输出
bar1:[]
bar2:[default value]
- 执行
bash test1.sh hi，输出
bar1:[hi]
bar2:[hi]
