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chapter4/function_rotate

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+function rotate
+{
+# PURPOSE: This function is used to give the end user
+# some feedback that "something" is running. It gives
+# a line rotating in a circle. This function is started
+# as a background process. Assign its PID to a variable
+# using
+#      rotate &       # To start
+#      ROTATE_PID=$!  # Get the PID of the last
+#                     # background job
+#
+#      At the end of execution just break out by
+#      killing the $ROTATE_PID process. We also need
+#      to do a quick "cleanup" of the leftover line of
+#      rotate output.
+#
+#      FROM THE SCRIPT:
+#           kill -9 $ROTATE_PID
+#           echo "\b\b "
+
+INTERVAL=1  # Sleep time between rotation intervals
+RCOUNT="0"  # For each RCOUNT the line rotates 1/8
+            # cycle
+
+while :     # Loop forever...until this function is killed
+do
+    (( RCOUNT = RCOUNT + 1 )) # Increment the RCOUNT
+
+    case $RCOUNT in
+    1) echo .-."\b\c"
+       sleep $INTERVAL
+       ;;
+    2) echo .\\."\b\c"
+       sleep $INTERVAL
+       ;;
+    3) echo "|\b\c"
+       sleep $INTERVAL
+       ;;
+    4) echo "/\b\c"
+       sleep $INTERVAL
+       ;;
+    *) RCOUNT="0" # Reset the RCOUNT to "0", zero.
+       ;;
+    esac
+done
+} # End of Function - rotate