Running commands as "$@"

[Cristian Zoicas]

Hello all

Let's assume the following script.

# ---- begin script runner.sh ----
eval "$@"
# ---- end script runner.sh ----

If we call this script with the following command line

    $ sh runner.sh ls -l

the 'ls -l' command will be executed.

Now, if a call the script with the commands

    $ sh runner.sh A=B

we get the following errors:

    runner.sh: 10: runner.sh: A=B: not found

Why the shell does not treat the first string in "$@" ('A=B'
in these cases) as the first possibile token of command (which
is an assignemnt)?

In addition, the problem is NOT solved by using 'eval "$@"'.
Apparently it works. For example the command

     $ sh runner.sh A=BCD

 works, but

     $ sh runner.sh A="B    CD"

gives an error. In this case the error (I think) comes
from the way the expansion of "$@" is performed: eval has to evaluate the
string "A=B   CD", so it treats A=B as an assignemnt and 'CD' as
a command.

I am curios what is going on and if there is any possibility of
running a command (any command, including an assignment) by using
a very simple invocation (someting like eval "$@").

Thank you in advance.
Cristian Zoicas