Add a section to bashrc idempotently

vagrant/provision.sh

@@ -65,34 +65,28 @@ su - $DEV_USER -c "$PYTHON $PROJECT_DIR/manage.py migrate --noinput && \
 
 # Add a couple of aliases to manage.py into .bashrc
 
-BASHRC="/home/$DEV_USER/.bashrc"
+BASHRC=/home/$DEV_USER/.bashrc
+BASHRC_BACKUP="${BASHRC}__pre_provision_backup"
 
-# Just put these values BASHRC_LINE_* to .bashrc:
-BASHRC_LINE_1="export PYTHONPATH=$PROJECT_DIR"
-BASHRC_LINE_2="alias dj='$PROJECT_DIR/manage.py'"
-BASHRC_LINE_3="alias djrun='dj runserver 0.0.0.0:8000'"
-BASHRC_LINE_4="export PS1='[$PROJECT_NAME \W]\\$ '"
-BASHRC_LINE_5="cd $PROJECT_DIR"
-BASHRC_LINE_ACTIVATE="source $VIRTUALENV_DIR/bin/activate"
-
-NEEDS_UPDATE_BASHRC_ACTIVATE=no
-
-# Prevent duplicate values in .bashrc from repeat provision
-# "seq 1 2" is used just in case: if the number of lines will increase
-for i in $(seq 1 5);
-do
-    eval "CURRENT_LINE=\$BASHRC_LINE_$i"
-    LINE_EXISTS=$(cat $BASHRC | grep -q "^$CURRENT_LINE" && echo yes || echo no)
-    if [[ "$LINE_EXISTS" == "no" ]];
-    then
-        echo $CURRENT_LINE >> $BASHRC
-        NEEDS_UPDATE_BASHRC_ACTIVATE=yes
-    fi
-done
-
-# Prevent a situation when "source" had called before env vars were provided
-if [[ "$NEEDS_UPDATE_BASHRC_ACTIVATE" == "yes" ]];
+if [[ ! -f "$BASHRC_BACKUP" ]];
 then
-	cat $BASHRC | grep -v "^$BASHRC_LINE_ACTIVATE" > "${BASHRC}.tmp" && mv ${BASHRC}.tmp $BASHRC
-	echo $BASHRC_LINE_ACTIVATE >> $BASHRC
+    # On the first provision run:
+    # Create backup of .bashrc if it doesn't exist
+    cp -f $BASHRC $BASHRC_BACKUP
+else
+    # If provision runs twice or more
+    # restore "pure" .bashrc from the backup
+    cp -f $BASHRC_BACKUP $BASHRC
 fi
+
+
+cat << EOF >> /home/$DEV_USER/.bashrc
+export PYTHONPATH=$PROJECT_DIR
+
+alias dj="$PROJECT_DIR/manage.py"
+alias djrun="dj runserver 0.0.0.0:8000"
+
+source $VIRTUALENV_DIR/bin/activate
+export PS1="[$PROJECT_NAME \W]\\$ "
+cd $PROJECT_DIR
+EOF