为什么“执行”给出“孩子异常退出”在这段代码中？

Question

我在 tcl 中运行此代码：-

set version [exec grep "INTERNAL VERSION:" mojave.log | sed -n -e "s/INTERNAL VERSION: //g" > xor.diff]

set p [exec diff ../log.warning.diff ../log.warning.gold >> xor.diff ]

对于最后一行，它在执行一些 diff 后给出以下错误：-

> RULE-311 WARNING: Gdsii layer number 85 datatype 0 has already been defined
> TCL-11   WARNING: Command "check quartz drc" is overridden, Quality Of
> TCL-11   WARNING: Command "delete marker quartz" is overridden, Quality Of
> TCL-11   WARNING: Command "import marker quartz" is overridden, Quality Of
> TCL-11   WARNING: Command "mojave! run filter log" is overridden, Quality Of
> TCL-11   WARNING: Command "run quartz gui" is overridden, Quality Of Results
> TCL-11   WARNING: Command "ui! mojave draw rectangle" is overridden, Quality
> TCL-11   WARNING: Command "ui! mojave set_context" is overridden, Quality Of
> TCL-12   WARNING: Overridden command "mojave! run filter log" is used,
child process exited abnormally
     while executing
"exec diff ../log.warning.diff ../log.warning.gold 2> xor.diff "
     invoked from within
"set p [exec diff ../log.warning.diff ../log.warning.gold 2> xor.diff ]"
     (file "test.tcl" line 4)
     invoked from within
"source test.tcl"

并且它没有在“xor.diff”文件中写入任何内容。

Answer 1

如果命令返回非零或者向 stderr 发送任何内容，exec 将返回错误。在 http 上有关于使用 catch 和 exec 的非常全面的讨论： //wiki.tcl.tk/exec

Answer 2

如果发现任何差异，diff（和comm）将退出非零，因此您可以重定向输出以将它们用作“此更改吗？”测试。对于 Tcl，您需要使用`|| :' 忽略退出状态的习惯用法。

PS“无用的 grep”... sed -n -e '/INTERNAL VERSION: /s//gp'