试着用if改写12.sh基本运行正常，唯独运行时空参数的情况会提示“期待一元表达式”的错误 # ./122.sh ./122.sh: 第 3 行:[: =: 期待一元表达式 ./122.sh: 第 5 行:[: =: 期待一元表达式 ./122.sh: 第 7 行:[: =: 期待一元表达式 ./122.sh: 第 9 行:[: =: 期待一元表达式 ./122.sh: 第 11 行:[: =: 期待一元表达式 ./122.sh: 第 13 行:[: =: 期待一元表达式 ./122.sh: 第 15 行:[: =: 期待一元表达式 ./122.sh: 第 17 行:[: =: 期待一元表达式 please enter: ./122.sh {start|stop|restart} 如下代码： #!/bin/bash #users if rewrite case-12.sh if [ $1 = start ];then echo $0 start... elif [ $1 = START ];then echo $0 start... elif [ $1 = stop ];then echo $0 stop... elif [ $1 = STOP ];then echo $0 stop... elif [ $1 = restart ];then echo $0 restart... elif [ $1 = RESTART ];then echo $0 restart... elif [ $1 = reload ];then echo $0 restart... elif [ $1 = RELOAD ];then echo $0 restart... else echo " please enter: $0 {start|stop|restart} " fi