$ date > '< abcd'
$ cat '< abcd'
<something>
$ tclsh8.5
% exec cat {< abcd}
couldn't read file " abcd": no such file or directory
哎呀。这是由于“exec”的规范造成的。
如果一个 arg（或一对 arg）具有下述形式之一，则 exec 使用它来控制子进程之间的输入和输出流。此类参数不会传递给子进程。以诸如“< fileName”，fileName 可以位于与“<”不同的单独参数中或者在同一个参数中没有中间空格”。
有没有办法解决这个问题？
$ date > '< abcd'
$ cat '< abcd'
<something>
$ tclsh8.5
% exec cat {< abcd}
couldn't read file " abcd": no such file or directory
whoops. This is due to the the specification of 'exec'.
If an arg (or pair of args) has one of the forms described below then it is used by exec to control the flow of input and output among the subprocess(es). Such arguments will not be passed to the subprocess(es). In forms such as “< fileName”, fileName may either be in a separate argument from “<” or in the same argument with no intervening space".
Is there a way to work around this?
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该值是否必须作为参数传递？如果没有，您可以使用类似以下的内容：
对于文件名，您可以（几乎总是）传递完全限定名称。完全限定名称可以通过文件规范化获得：
但是如果您需要传入一个参数，其中
<（或> ;) 是第一个字符，你被卡住了。exec命令始终使用重定向等参数；与 Unix shell 不同，您不能仅使用引用来解决它。但您可以使用帮助程序。因此，在 Unix 上你可以这样做：
(子程序只是将其自身替换为你想要运行的内容，传递你真正想要的参数。你可能需要使用
string map或regsub将反斜杠放在有问题的元字符前面。）在 Windows 上，您必须编写一个批处理文件并运行它，这有很多警告和令人讨厌的副作用，特别是对于 GUI 应用程序。
Does the value have to be passed as an argument? If not, you can use something like this:
For filenames, you can (almost always) pass the fully qualified name instead. The fully qualified name can be obtained with
file normalize:But if you need to pass in an argument where
<(or>) is the first character, you're stuck. Theexeccommand always consumes such arguments as redirections; unlike with the Unix shell, you can't just use quoting to work around it.But you can use a helper program. Thus, on Unix you can do this:
(The subprogram just replaces itself with what you want to run passing in the argument you really wanted. You might need to use
string maporregsubto put backslashes in front of problematic metacharacters.)On Windows, you have to write a batch file and run that, which has a lot of caveats and nasty side issues, especially for GUI applications.
一种简单的解决方案：确保单词不以重定向字符开头：
一种稍微复杂一点的解决方案：
此 Tcl Wiki 上的页面稍微讨论了这个问题。
One simple solution: ensure the word does not begin with the redirection character:
One slightly more complex:
This page on the Tcl Wiki talks about the issue a bit.
你试过这个吗？
Have you tried this?
尝试：
set myfile "< abcd"
exec cat $myfile
Try:
set myfile "< abcd"
exec cat $myfile