Argument Debugging in Bash

Debugging bash scripts? Need to see what arguments you get? See the
difference between echo "$@" and (the bash builtin) printf "%q".
First we set some tricky arguments and then set them again, pasting
the output of the inspection command.

As you can see, plain echo degrades quickly:

e5:~ # set -- arg1 "arg two" back\\slash "'single'" '"double"'
e5:~ # echo "$@"
arg1 arg two back\slash 'single' "double"
e5:~ # set -- arg1 arg two back\slash 'single' "double"
e5:~ # echo "$@"
arg1 arg two backslash single double

But printf %q keeps working:

e5:~ # set -- arg1 "arg two" back\\slash "'single'" '"double"'
e5:~ # printf "%q " "$@"; echo
arg1 arg\ two back\\slash \'single\' \"double\"
e5:~ # set -- arg1 arg\ two back\\slash \'single\' \"double\"
e5:~ # printf "%q " "$@"; echo
arg1 arg\ two back\\slash \'single\' \"double\"