Add command_exists function to base.plugin from http://stackoverflow.com/questions/592620/check-if-a-program-exists-from-a-bash-script:

plugins/base.plugin.bash

@@ -11,19 +11,11 @@ function myip {
   echo "Your public IP is: ${bold_green} $res ${normal}"
 }
 
-# Make a directory and immediately 'cd' into it
-
 function mkcd(){
 	mkdir -p "$*"
 	cd "$*"
 }
 
-# Search through directory contents with grep
-
-function lsgrep(){
-  ls | grep "$*"
-}
-
 # View man documentation in Preview
 pman () {
    man -t "${1}" | open -f -a $PREVIEW
@@ -77,6 +69,11 @@ function t() {
 	 fi
 }
 
+# Checks for existence of a command
+command_exists () {
+    type "$1" &> /dev/null ;
+}
+
 # List all plugins and functions defined by bash-it
 function plugins-help() {