[cs631apue] Question about -c option

[Jan Schaumann]

gcheng2 <gcheng2 at stevens.edu> wrote:
 
> Is -c option only for commands without options?

No, you can pass any command or sequence of commands via the "-c".

For example:

sish -c "ls"
sish -c "ls >out"
sish -c "ls | wc -l"

In this regard your shell is no different from, say, bash:

bash -c "ls"
bash -c "ls >out"
bash -c "ls | wc -l"

>  How do we handle
> commands like
>    sish -c "echo $?"
> 
> $? will be auto transferred to a number(exit status of previous
> command), we could not read the string "$?".

That is because your current shell interpretes $?.  Use single quotes to
avoid interpretation of $:

sish -c 'echo $?'

(Although that is not a useful command, since there is no previous
command from which to get the exit status.)

-Jan