Add zplug auto update plugin

home/.zsh/plugins/autoupdate.zsh

@@ -0,0 +1,41 @@
+_zplug-check-interval() {
+  now=$(date +%s)
+  if [ -f "${1}" ]; then
+    last_update=$(cat "${1}")
+  else
+    last_update=0
+  fi
+  interval=$(expr ${now} - ${last_update})
+  echo "${interval}"
+}
+
+_zplug-check-for-updates() {
+  if [ -z "${ZPLUG_PLUGIN_UPDATE_DAYS}" ]; then
+    ZPLUG_PLUGIN_UPDATE_DAYS=14
+  fi
+
+  if [ -z "${ZPLUG_PLUGIN_UPDATE_FILE}" ]; then
+    ZPLUG_PLUGIN_UPDATE_FILE="${ZPLUG_HOME:-}/.zplug_plugin_lastupdate"
+  fi
+
+  local day_seconds=$(expr 24 \* 60 \* 60)
+  local plugins_seconds=$(expr ${day_seconds} \* ${ZPLUG_PLUGIN_UPDATE_DAYS})
+
+  local last_plugin=$(_zplug-check-interval ${ZPLUG_PLUGIN_UPDATE_FILE})
+
+  if [ ${last_plugin} -gt ${plugins_seconds} ]; then
+    echo "It has been $(expr ${last_plugin} / $day_seconds) days since your zplug plugins were updated"
+    zplug update
+
+    date +%s >! ${ZPLUG_PLUGIN_UPDATE_FILE}
+    zplug clean --force
+  fi
+}
+
+zmodload zsh/system
+lockfile=${ZPLUG_HOME:-~}/.zplug_autoupdate_lock
+touch $lockfile
+if ! which zsystem &> /dev/null || zsystem flock -t 1 $lockfile; then
+  _zplug-check-for-updates
+  command rm -f $lockfile
+fi

home/.zshrc

@@ -37,6 +37,7 @@ zplug "plugins/asdf",    from:oh-my-zsh
 zplug "zsh-users/zsh-completions"
 zplug "zsh-users/zsh-syntax-highlighting", defer:2
 
+zplug "~/.zsh/plugins", from:local
 zplug "~/.zsh/cmd",     from:local, use:'(*).sh',          as:command, rename-to:'$1'
 zplug "~/.zsh/themes",  from:local, use:cheetah.zsh-theme, as:theme