Linux bash fi

Linux bash fi

Linux bash fi

if..else..fi allows to make choice based on the success or failure of a command.

if..else..fi 允许根据命令的成功或失败进行选择。

if [ conditional expression ]
then
  statement1
  statement2
  .
fi

if [ expression ] 
then 
   Statement(s) to be executed if expression is true 
fi

demo

if [ ! -x /usr/bin/axel ]
then echo "axel is not installed, perform this?(y/n)"
    read ops
    case $ops in
     y) if apt-get install axel -y --force-yes
           then echo "axel installed"
        else echo "unable to install the axel. you are using sudo?" ; exit
        fi ;;
     n) echo "not possible usage apt-fast" ; exit ;;
    esac
fi