Calling emacsclient from ansi-term makes emacsclient hang, how do I get around this?

See "with-editor" : https://github.com/magit/with-editor/blob/master/README.md

You don't have to display an error when using emacsclient from inside term : you can make it use your current Emacs instance.

For shell-mode, there is a package called "shx", which provides useful shell commands like :e (to edit a file), :diff (to ediff 2 files ), :find (run find command and open files in clickable output) etc.

Edit : and yes, you never need to kill the server process too. On unixes, just send it a USR2 signal and Emacs would drop whatever it was doing and unfreeze from most situations including this one.

" killall -USR2 emacs"

It looks like ansi-term sets the TERM environment variable to eterm, possibly extended to eterm-color or similar. You can use this to define emacs to an appropriate alias whenever you're already in ansi-term inside emacs. Something like this in your .bashrc:

case "$TERM" in 
     eterm*)
         alias emacs=emacsclient
         ;;
     *)
         ## code to run for non-eterm shells
         ;;
esac

If that doesn't work, another option is the environment variable INSIDE_EMACS, which is set to <emacs version>,term<term version>. Note that shell-mode sets this to <emacs version>,comint, so if you use both you'll want to distinguish between them with your test:

case "$INSIDE_EMACS" in 
     *term*)
         alias emacs=emacsclient
         ;;
     *comint*)
         ## code to run for shell-mode
         ;;
     *)
         ## code for non-emacs shells
esac