linux tclsh exec cd,参数-TCL /期望-exec-如何使用参数执行程序

我正在tclsh中尝试使用TCL命令exec,这是我的结果：

% set show_me_dir "ls"

ls

% exec $show_me_dir

VboxSharedFolder

% set show_me_dir "ls -la"

ls -la

% exec $show_me_dir

couldn't execute "ls -la": no such file or directory

% set show_me_dir {ls -la}

ls -la

% exec $show_me_dir

couldn't execute "ls -la": no such file or directory

% ls -la

total 141

d---------+ 1 wakatana Domain Users 0 Jan 22 19:12 .

d---------+ 1 wakatana Domain Users 0 Apr 16 2014 ..

----------+ 1 wakatana Domain Users 20214 Jan 23 18:43 .bash_history

----------+ 1 wakatana Domain Users 1494 Apr 15 2014 .bash_profile

----------+ 1 wakatana Domain Users 7593 Jan 22 19:03 .bashrc

d---------+ 1 wakatana Domain Users 0 Jan 15 14:56 VboxSharedFolder

%

有人可以解释一下如何使用参数执行命令吗？

编辑：

仅在将命令行拆分为各个参数之后,才将变量$action扩展为字符串“ piemiddle app