Replace $BASH with $BASH_IT because $BASH is already used on *nix systems for the pathname to the executable (http://www.gnu.org/software/bash/manual/html_node/Bash-Variables.html#Bash-Variables)

install.sh

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-BASH="$HOME/.bash_it"
+BASH_IT="$HOME/.bash_it"
 
 cp $HOME/.bash_profile $HOME/.bash_profile.bak
 
@@ -30,24 +30,24 @@ done
 
 function load_all() {
   file_type=$1
-  [ ! -d "$BASH/$file_type/enabled" ] && mkdir "$BASH/${file_type}/enabled"
-  ln -s $BASH/${file_type}/available/* "${BASH}/${file_type}/enabled"
+  [ ! -d "$BASH_IT/$file_type/enabled" ] && mkdir "$BASH_IT/${file_type}/enabled"
+  ln -s $BASH_IT/${file_type}/available/* "${BASH_IT}/${file_type}/enabled"
 }
 
 function load_some() {
     file_type=$1
-    for file in `ls $BASH/${file_type}/available`
+    for file in `ls $BASH_IT/${file_type}/available`
     do
-      if [ ! -d "$BASH/$file_type/enabled" ]
+      if [ ! -d "$BASH_IT/$file_type/enabled" ]
       then
-        mkdir "$BASH/$file_type/enabled"
+        mkdir "$BASH_IT/$file_type/enabled"
       fi
       while true
       do
         read -p "Would you like to enable the ${file%.*.*} $file_type? [Y/N] " RESP
         case $RESP in
         [yY])
-          ln -s "$BASH/$file_type/available/$file" "$BASH/$file_type/enabled"
+          ln -s "$BASH_IT/$file_type/available/$file" "$BASH_IT/$file_type/enabled"
           break
           ;;
         [nN])