What you're suggesting is that the shell should have every possible command builtin and not call external programs.
Let's analyze your example with 'rm': it works as long as 'rm' is an internal routine. If it's an external program, independently of the syntax you use to specify the arguments, sooner or later the shell will need to actually call the 'rm' executable, and to pass '-rf' to it as argument number 1. The 'rm' executable will then examine its arguments, see that the first one begins with a hyphen and interpret it as an option.
As I said, the only way to avoid all this would be to replace 'rm' with an internal routine. Then you would replace 'cp' and 'ln', and what else? Of course 'echo' and 'printf', 'cat', 'ls', 'cd' maybe, why not 'find' and 'grep'? What about 'head', 'tail', 'cut'? Don't forget 'sed' and 'awk'... the list is getting longer and longer. Where do you draw the line?
Seriously, the only mitigation would be to define a function to 'sanitize' an argument to make it appear as a file if used as an argument to an external program. Something like:
force_file() {
case "$1" in
-*) echo "./$1" ;;
*) echo "$1" ;;
esac
Let's analyze your example with 'rm': it works as long as 'rm' is an internal routine. If it's an external program, independently of the syntax you use to specify the arguments, sooner or later the shell will need to actually call the 'rm' executable, and to pass '-rf' to it as argument number 1. The 'rm' executable will then examine its arguments, see that the first one begins with a hyphen and interpret it as an option.
As I said, the only way to avoid all this would be to replace 'rm' with an internal routine. Then you would replace 'cp' and 'ln', and what else? Of course 'echo' and 'printf', 'cat', 'ls', 'cd' maybe, why not 'find' and 'grep'? What about 'head', 'tail', 'cut'? Don't forget 'sed' and 'awk'... the list is getting longer and longer. Where do you draw the line?
Seriously, the only mitigation would be to define a function to 'sanitize' an argument to make it appear as a file if used as an argument to an external program. Something like:
}This doesn't work with 'echo' though.