Macro cmd_lib::run_cmds

macro_rules! run_cmds {
    ($x:ident $($other:tt)*) => { ... };
    (&$s:expr; $x:tt $($other:tt)*) => { ... };
    (&$s:expr; $x:tt; $($other:tt)*) => { ... };
    (&$s:expr;) => { ... };
    ($($arg:tt)*) => { ... };
}

run_cmds! --> CmdResult

if any command fails, just return Err(...)

run_cmds!{
    date
    ls -l /file
}