A script for quickly opening and attaching to tmux sessions

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#!/bin/bash
# A script for quickly opening and attaching to tmux sessions
#
# It takes two optional arguments: a session name and directory.
# If no session name is provided, "main" is used. If no
# directory is provided, the current directory is used. Then
# it simply switches to that session. If that session doesn't
# exist, it creates it first and sets the default session. You'd
# think this would be trivial, but tmux requires many different
# options to create/attach a session based on the context.
# This just works.

usage() {
	echo usage: $(basename "$0") [session] [default-directory]
	echo
	echo "If no session is provided, 'main' is used. If a default-directory is"
	echo "provided, then that directory will be used for all new windows inside"
	echo "the session."
	echo
	echo "Of note, this utility detects whether or not it is being run inside"
	echo "an existing tmux connection and can safely create or switch sessions"
	echo "without any nesting issues."
	echo
	echo "  -l	list sessions"
	echo "  -h	display this help message"
}

## Command line options

while getopts "hl" arg; do
	case $arg in
		h) usage && exit;;
		l) tmux list-sessions && exit;;
	esac
done

## Get requested session information

SESSION_NAME="$1"
ATTACH_DIR="$2"
DEFAULT_SESSION="main"

# Ensure the session name is set
if [[ -z "$SESSION_NAME" ]]; then
	if [[ -n "$DEFAULT_SESSION" ]]; then
		SESSION_NAME="$DEFAULT_SESSION"
	fi
fi

## Connect to the session

# Create the session if it doesn't exist
if [[ -n "$ATTACH_DIR" && -d "$ATTACH_DIR" ]]; then
	TMUX= tmux new-session -d -s "$SESSION_NAME" -c "$ATTACH_DIR" 2>/dev/null
else
	TMUX= tmux new-session -d -s "$SESSION_NAME" 2>/dev/null
fi

# Connect to the session
if [[ -n "$TMUX" ]]; then
	# If we're already inside tmux, use switch-client
	if [[ -n "$ATTACH_DIR" && -d "$ATTACH_DIR" ]]; then
		# TODO: Figure out how to change the directory when switching
		# from inside tmux
		TMUX="" tmux switch-client -t "$SESSION_NAME" # \; attach -c "$ATTACH_DIR"
	else
		TMUX="" tmux switch-client -t "$SESSION_NAME"
	fi
else
	# If we're not inside tmux, use attach-session
	if [[ -n "$ATTACH_DIR" && -d "$ATTACH_DIR" ]]; then
		TMUX="" tmux attach-session -t "$SESSION_NAME" -c "$ATTACH_DIR"
	else
		TMUX="" tmux attach-session -t "$SESSION_NAME"
	fi
fi