Problems with the open command

[ecco]

For a few days I have problems with the open command:

kalle: /Applications > which open
/usr/bin/open
kalle: /Applications > open .
zsh: bus error open .
kalle: /Applications > /usr/bin/open .
kalle: /Applications >

I'm not quite sure but I think this problem wasn't there until the last Apple Security Update. Can you help me?

[ecco]

ups, I found the reason.
there was a shell alias defined for open:
open=''
I removed the alias and now the open command works again :-)
But I don't know where this alias definition came from...