Problem: Shmux isn't readily available

Solution:

 - Import its code in a separate repository
 - Clean up the code, insert some commentaries
 - Make sure it complies with `shellcheck`

shmux

@@ -0,0 +1,73 @@
+#!/usr/bin/env bash
+# shmux is shell tmuxinator for a generic project
+
+## Error codes
+_err_no_target=1
+_tmux_session_not_found=1
+
+_session="$(basename "$1")"
+_session="${_session/./_}"
+
+tmux start-server || true
+
+# tmux has-session returns value that we'll refer to via $?
+tmux has-session -t "$_session"
+if [ "$?" -eq "$_tmux_session_not_found" ]; then # If there is no session
+if [ -n "$1" ]; then # And we have an argument
+  # It's OK to fail
+  cd "$1" || true
+  _wd="$(pwd)"
+  _post_hook_maybe=""
+
+  TMUX="$(tmux new-session -d -s "$_session" -n vim)"
+  tmux new-window -c "$_wd" -t "$_session:1" -n tasks 
+  tmux new-window -c "$_wd" -t "$_session:2" -n git
+  tmux new-window -c "$_wd" -t "$_session:3" -n grep
+  tmux new-window -c "$_wd" -t "$_session:4" -n mon0
+  tmux new-window -c "$_wd" -t "$_session:5" -n mon1
+
+  tmux send-keys -t "$_session:0" "vim ." C-m
+  tmux send-keys -t "$_session:2" "git log --graph --decorate --all -n7 | grep ." C-m
+  if [ -n "$_post_hook_maybe" ]; then
+    for x in {2..5}; do
+      tmux send-keys -t "$_session:$x" "$_post_hook_maybe" C-m
+    done
+  fi
+
+  if [ -d tasks ]; then
+    _split="horizontal"
+    for x in tasks/*; do
+      # Run buffer hook in the current split
+      tmux send-keys -t "$_session:1" "$_post_hook_maybe" C-m
+      # Run the task the current split
+      tmux send-keys -t "$_session:1" "$x" C-m
+      # Create a new split, spiral layout
+      if [[ $_split == "horizontal" ]]; then
+        tmux split-window -h -t "$_session:1"
+        _split="vertical"
+      else
+        tmux split-window -t "$_session:1"
+        _split="horizontal"
+      fi
+    done
+    # Exit last split (it didn't have a task)
+    tmux send-keys -t "$_session:1" "exit" C-m
+  else
+    tmux send-keys -t "$_session:1" "$_post_hook_maybe" C-m
+  fi
+
+  tmux select-window -t 0
+fi
+fi
+
+# We can run tmux in detached mode with -d
+if [ "$2" == "-d" ]; then
+  exit 0;
+fi
+# Otherwise we attach to the session if we're outside tmux
+if [ -z "$TMUX" ]; then
+  tmux -u attach-session -t "$_session"
+# And switch to the session if we're inside
+else
+  tmux -u switch-client -t "$_session"
+fi