Add tmux version check

TPM won't work unless tmux version is 1.9 or higher.

Closes #2

README.md

@@ -4,7 +4,7 @@ Installs and loads TMUX plugins.
 
 ### Installation
 
-Requirements: `git`
+Requirements: `tmux` version 1.9 (or higher), `git`
 
 Clone TPM:
 

scripts/check_tmux_version.sh

@@ -0,0 +1,78 @@
+#!/usr/bin/env bash
+
+VERSION="$1"
+UNSUPPORTED_MSG="$2"
+
+get_tmux_option() {
+	local option=$1
+	local default_value=$2
+	local option_value=$(tmux show-option -gqv "$option")
+	if [ -z "$option_value" ]; then
+		echo "$default_value"
+	else
+		echo "$option_value"
+	fi
+}
+
+# Ensures a message is displayed for 5 seconds in tmux prompt.
+# Does not override the 'display-time' tmux option.
+display_message() {
+	local message="$1"
+
+	# display_duration defaults to 5 seconds, if not passed as an argument
+	if [ "$#" -eq 2 ]; then
+		local display_duration="$2"
+	else
+		local display_duration="5000"
+	fi
+
+	# saves user-set 'display-time' option
+	local saved_display_time=$(get_tmux_option "display-time" "750")
+
+	# sets message display time to 5 seconds
+	tmux set-option -gq display-time "$display_duration"
+
+	# displays message
+	tmux display-message "$message"
+
+	# restores original 'display-time' value
+	tmux set-option -gq display-time "$saved_display_time"
+}
+
+# this is used to get "clean" integer version number. Examples:
+# `tmux 1.9` => `19`
+# `1.9a`     => `19`
+get_digits_from_string() {
+	local string="$1"
+	local only_digits="$(echo "$string" | tr -dC '[:digit:]')"
+	echo "$only_digits"
+}
+
+tmux_version_int() {
+	local tmux_version_string=$(tmux -V)
+	echo "$(get_digits_from_string "$tmux_version_string")"
+}
+
+unsupported_version_message() {
+	if [ -n "$UNSUPPORTED_MSG" ]; then
+		echo "$UNSUPPORTED_MSG"
+	else
+		echo "Error, Tmux version unsupported! Please install Tmux version $VERSION or greater!"
+	fi
+}
+
+exit_if_unsupported_version() {
+	local current_version="$1"
+	local supported_version="$2"
+	if [ "$current_version" -lt "$supported_version" ]; then
+		display_message "$(unsupported_version_message)"
+		exit 1
+	fi
+}
+
+main() {
+	local supported_version_int="$(get_digits_from_string "$VERSION")"
+	local current_version_int="$(tmux_version_int)"
+	exit_if_unsupported_version "$current_version_int" "$supported_version_int"
+}
+main

tpm

@@ -2,6 +2,8 @@
 
 CURRENT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 
+SUPPORTED_TMUX_VERSION="1.9"
+
 # Ensures TMUX_PLUGIN_MANAGER_PATH global env variable is set.
 # Default tpm path is "$HOME/.tmux/plugins/". That's where all the plugins are
 # downloaded.
@@ -27,9 +29,15 @@ set_tpm_key_binding() {
 	$CURRENT_DIR/scripts/key_binding.sh
 }
 
+supported_tmux_version_ok() {
+	$CURRENT_DIR/scripts/check_tmux_version.sh "$SUPPORTED_TMUX_VERSION"
+}
+
 main() {
-	set_tpm_path
-	set_tpm_key_binding
-	source_plugins
+	if supported_tmux_version_ok; then
+		set_tpm_path
+		set_tpm_key_binding
+		source_plugins
+	fi
 }
 main