当有人这么问的时候，通常要问的是 要如何判断是否是一个 interactive shell? 或是问要如何判断是否是 最上层的 shell ? 若你是要问 "是否在 login shell 中"（注：就是在做完 .cshrc 后，会 再去做 .login），那么你也许用 "ps" 和 "$$" 随便弄一弄，就能知道了 。因为通常 login shells 的名字在 "ps" 看起来都是由 '-' 做开头的。 如果你是真的对另外两个问题感兴趣，那么这里有个方法可以让你在 .cshrc 中判断。 if (! $?CSHLEVEL) then # # This is a "top-level" shell, # perhaps a login shell, perhaps a shell started up by # 'rsh machine some-command' # This is where we should set PATH and anything else we # want to apply to every one of our shells. # setenv CSHLEVEL 0 set home = ~username # just to be sure source ~/.env # environment stuff we always want else # # This shell is a child of one of our other shells so # we don't need to set all the environment variables again. # set tmp = $CSHLEVEL @ tmp setenv CSHLEVEL $tmp endif # Exit from .cshrc if not interactive, e.g. under rsh if (! $?prompt) exit # Here we could set the prompt or aliases that would be useful # for interactive shells only. source ~/.aliases
