If it's what I think you're asking, you can set this, but it's really hard to find.  (It's not in the System Preferences app.)

On OS X in the Japanese interface, there's no "Romaji" input, but based on some screenshots I found, I'm assuming this is "英字" (eiji, i.e., halfwidth Latin characters).  All of the Japanese input methods use a system called Kotoeri (ことえり).  When a Kotoeri input method is selected, from the keyboard layout menubar menu in the top right, choose "環境設定を表示" ("Show Preferences", maybe?), which is indented a bit under a "Kotoeri" heading.  (It disappears if you have a non-Kotoeri input method selected.)  There, you can choose a base keyboard input method for Kotoeri to use.

Alternatively, there's nothing special about the (half-width) Romaji / 英字 characters: they're just Latin characters.  I don't even have this layout enabled.  When I want to type Romaji, I just use my (western) layout.  I can't tell what benefit there might be to using Kotoeri for this.

Sadly, I don't know anything about Chinese, so you're on your own there, but I suspect it has a similarly well-hidden setting.  :-)  I enabled the Chinese keyboard layouts here, and got some extra menuitems in the keyboard layout menu, but nothing that looked quite the same as the Japanese settings.

Specifying the keyboard layout for Chinese input
I'm using dash(sh) or bash or zsh. If possible, I would prefer to put in common place.

I want to put proper PS1 settings when I interactive with shell, so these situation should be considered


login (show PS1)
su
sudo
script (Don't show PS1)


I was put PS1 on .bashrc, but it seems not always workable.
