nyos@hex:~/src$ gcc -O3 checknmea.c -o checknmea
nyos@hex:~/src$ ./checknmea 'GLGSV,2,1,08,86,26,188,33,74,28,112,,66,11,286,,76,31,313,*60'
NMEA doesn't begin with '$' GLGSV,2,1,08,86,26,188,33,74,28,112,,66,11,286,,76,31,313,*60
nyos@hex:~/src$ ./checknmea '$GLGSV,2,1,08,86,26,188,33,74,28,112,,66,11,286,,76,31,313,60'
NMEA doesn't contain '*' $GLGSV,2,1,08,86,26,188,33,74,28,112,,66,11,286,,76,31,313,60
nyos@hex:~/src$ ./checknmea '$GLGSV,2,1,08,86,26,188,33,74,28,112,,66,11,286,,76,31,313,*6x0'
Invalid hex digit: $GLGSV,2,1,08,86,26,188,33,74,28,112,,66,11,286,,76,31,313,*6x0
nyos@hex:~/src$ ./checknmea '$GLGSV,2,1,08,86,26,188,33,74,28,112,,66,11,286,,76,31,313,*0'
Checksum missing from the end: $GLGSV,2,1,08,86,26,188,33,74,28,112,,66,11,286,,76,31,313,*0
nyos@hex:~/src$ ./checknmea '$GLGSV,2,1,08,86,26,188,33,74,28,112,,66,11,286,,76,31,313,*40'
Checksums are different: 60!=40 $GLGSV,2,1,08,86,26,188,33,74,28,112,,66,11,286,,76,31,313,*40
nyos@hex:~/src$ ./checknmea '$GLGSV,2,1,08,86,26,188,33,74,28,112,,66,11,286,,76,31,313,*60'
nyos@hex:~/src$