cat>bad_file<<! warn before precious keystrokes wasted

[Dan Jacobson]

there i was typing at my terminal
$ cat>a<<!
> bla bla bla
> bla bla bla
> !
bash: a: cannot overwrite existing file

blaaaast! now he tells me!
why can't you tell me before I start typing?

$ cd /;cat>a<<!
> vvv
> !
bash: a: Permission denied

therefore, warn of noclobber or permission stuff beforehand. however i
bet this is another of 'that's not how the shell works' :-)