对echo(),print(),print_r()的区别叙述不正确的是()。
A、Echo是语句,没有返回值
B、Print是函数,有返回值
C、Print_r可以输出基本变量及符合变量的内容
D、三者都能输出变量,echo和print一样,print_r可以输出复合变量的内容
A、Echo是语句,没有返回值
B、Print是函数,有返回值
C、Print_r可以输出基本变量及符合变量的内容
D、三者都能输出变量,echo和print一样,print_r可以输出复合变量的内容
A、echo The current working path is $PWD. B、echo "The current working path is $PWD." Echo hello C、echo 'The current working path is $PWD.' Echo hello D、echo "The current working path is `pwd`." E、echo The current working path is $PWD. Echo hello
A、向目标主机发送UDP Echo Request数据包,等待对方回应UDP Echo Reply数据包 B、向目标主机发送ICMP Echo Request数据包,等待对方回应ICMP Echo Reply数据包 C、向目标主机发送UDP Echo Reply数据包,等待对方回应ICMP Echo Request数据包 D、向目标主机发送ICMP Echo Reply数据包,等待对方回应ICMP Echo Request数据包
A、echo The current working path is $PWD. B、echo 'The current working path is $PWD.' C、echo "The current working path is $PWD." D、echo "The current working path is `pwd`."
A、A、echo work>/etc/at.allow B、B、echo work>/etc/at.deny C、C、echo>/etc/at.allow D、D、echo>/etc/at.deny E、E、touch /etc/at.allow