-e file
              True if file exists.
       -f file
              True if file exists and is a regular file.
       -r file
              True if file exists and is readable.
       -s file
              True if file exists and has a size greater than zero.
       -O file
              True if file exists and is owned by the effective user id.
       -G file
              True if file exists and is owned by the effective group id.