John Hawley cried from the depths of the abyss...

> Script should probably have the full path name for the ping_check.txt file, so you know where to look for it.  (ie. /tmp/ping_check.txt). 

Correction - not probably, but with out a doubt SHOULD have 
/full/path/to/ping_check.txt

and

/full/path/to/backup_script