Shell Script Basic

@commands
1. Break & Continue
2. source (.)
3. shift
4. trap
5. expr, $((…))
6. xargs
7. dialog

@skills
1. here document
2. parameter substitution

@practice
1. questionnaire
2. cd manager

@reference
Beginning Linux Programming, 4th Edition, by Neil Matthew, Richard Stones.
Chapter 2. Shell Programming