我不知道为什么下面指示的行返回1而((count))的后续执行返回0.
- [me@server ~]$count=0
- [me@server ~]$echo $?
- 0
- [me@server ~]$count++
- -bash: count++: command not found
- [me@server ~]$(count++)
- -bash: count++: command not found
- [me@server ~]$((count++))
- [me@server ~]$echo $?
- 1 <------THIS WHY IS IT 1 AND NOT 0??
- [me@server ~]$((count++))
- [me@server ~]$echo $?
- 0
- [me@server ~]$((count++))
- [me@server ~]$echo $?
- 0
- [me@server ~]$echo $count
- 3
请参阅帮助允许页面中的摘录,
If the last ARG evaluates to 0,let returns 1; 0 is returned
otherwise.
由于操作是后递增的,((计数)),第一次保留0,因此返回1
注意,对于预增量((count))也不会发生同样的情况,因为在第一次迭代时,该值设置为1.
- $unset count
- $count=0
- $echo $?
- 0
- $++count
- -bash: ++count: command not found
- $echo $?
- 127
- $((++count))
- $echo $?
- 0