made requirements explicit in both README.md and .tmux.conf

.tmux.conf

@@ -1175,6 +1175,19 @@ run -b '[ -z "#{window_active}" ] && [ -z "#{version}" ] && tmux set display-tim
 #
 # _apply_configuration() {
 #
+#   if ! command -v perl > /dev/null 2>&1; then
+#     tmux run -b 'tmux set display-time 3000 \; display "This configuration requires perl" \; set -u display-time'
+#     return
+#   fi
+#   if ! command -v sed > /dev/null 2>&1; then
+#     tmux run -b 'tmux set display-time 3000 \; display "This configuration requires sed" \; set -u display-time'
+#     return
+#   fi
+#   if ! command -v awk > /dev/null 2>&1; then
+#     tmux run -b 'tmux set display-time 3000 \; display "This configuration requires awk" \; set -u display-time'
+#     return
+#   fi
+#
 #   # see https://github.com/ChrisJohnsen/tmux-MacOSX-pasteboard
 #   if command -v reattach-to-user-namespace > /dev/null 2>&1; then
 #     default_shell="$(tmux show -gv default-shell)"

README.md

@@ -10,8 +10,9 @@ Installation
 
 Requirements:
 
-  - tmux **`>= 2.1`** running inside Linux, Mac, OpenBSD, Cygwin or WSL (Bash on
-    Ubuntu on Windows)
+  - tmux **`>= 2.1`** (soon `>= 2.4`) running inside Linux, Mac, OpenBSD, Cygwin
+    or WSL
+  - awk, perl and sed
   - outside of tmux, `$TERM` must be set to `xterm-256color`
 
 To install, run the following from your terminal: (you may want to backup your