Sams Teach Yourself Shell Programming in 24 Hours, Second Edition

Questions

1:	Which of the following are valid variable names? _FRUIT_BASKET 1_APPLE_A_DAY FOUR-SCORE&7YEARS_AGO Variable
2:	Is the following sequence of array assignments valid in sh, ksh, and bash? $ adams[0]=hitchhikers_guide $ adams[1]=restaurant $ adams[3]=thanks_for_all_the_fish $ adams[42]=life_universe_everything $ adams[5]=mostly_harmless
3:	Given the preceding array assignments, how would you access the array item at index 5 in the array adams? How would you access every item in the array?
4:	What is the difference between an environment variable and a local variable?