Many articles are available about running Emacs in client/server mode. However, when I tried to do it in my particular environment (macOS 11.0.1 Big Sur, using zsh), some tweaks were still needed. So I figured that it’s probably useful to document my setup.
In macOS, the Emacs executable is /Applications/Emacs.app/Contents/MacOS/Emacs. To run Emacs in its regular (non-server) operation mode, I defined two shell commands in .zshrc: emacs runs Emacs in GUI mode in a macOS window, whereas emacsnw runs Emacs in text mode within the terminal. I started by defining emacs as an alias similar to emacsnw, but the problem was that it’s easy to forget the & to put it running in the background, so I had to rewrite it as a function.
function emacs() { /Applications/Emacs.app/Contents/MacOS/Emacs $@ &; }
alias emacsnw="/Applications/Emacs.app/Contents/MacOS/Emacs -nw"
I used to use emacsnw exclusively, because I thought that managing an addition macOS window was a hassle. However, I eventually decided to switch to the GUI mode because I liked how org-mode documents are rendered in GUI mode. The problem with the emacs shell command, though, was that if I use it to open a second document, a new instance of Emacs would be launched. What I wanted was for the running Emacs to open a new buffer. This was when I realized that I should investigate the client/server mode.
To start the Emacs server, it is possible to ask macOS to launch the Emacs daemon automatically when the user logs in (see here). However, I never found this to be useful. Instead, I decided to use the Emacs client to start the server, if it cannot detect a running Emacs. It should be simple enough to implement, but the Emacs client (/Applications/Emacs.app/Contents/MacOS/bin/emacsclient) seems to have problems locating the server from time to time. So I use a shell script emacsserver to locate the socket associated with Emacs:
lsof -c Emacs | grep server | tr -s " " | cut -d' ' -f8
The unix command lsof lists all the files opened by a process. If Emacs server is already running, this script returns the socket file. Otherwise, it returns nothing. I put this script in ~/bin.
The next step is easy. I use a shell script called ec (which stands for emacs client) to evoke Emacs. If ec detects a socket file (meaning that the server is running), it tells the server to open a new file. Otherwise, it launches Emacs and starts the server:
#!/bin/zsh
socket_file=$(~/bin/emacsserver)
emacs=/Applications/Emacs.app/Contents/MacOS/Emacs
emacsclient=/Applications/Emacs.app/Contents/MacOS/bin/emacsclient
if [[ $socket_file == "" ]]; then
echo "starting Emacs server..."
$emacs --chdir $PWD --execute "(server-start)" $@ &
else
$emacsclient -n $@ --socket-name $socket_file
fi
Another associated issue was that I wanted to tell git to use Emacs rather than vi. For this purpose, I don’t need the server so I just added the following to .zshenv:
export VISUAL="/Applications/Emacs/Contents/MacOS/Emacs -nw"
export EDITOR="/Applications/Emacs/Contents/MacOS/Emacs -nw"