1. Bash Programming Andrew Vandever RHC{T,E,I,X} [email_address] http://avcomp.net

2. Bash Programming Andrew Vandever Technical Training Resources Scripting Basics Expansion Loops Conditional Statements I/O Redirection User Input System V Init Scripts 3. Scripting Basics

Bourne Again Shell

4. Posix-Compliant 5. Interactive Shell Script 6. Automation, Repetition 7. NOT exhaustive 8. NOT covering external programs 9. Check out guides on tldp.org 10. Scripting Basics

Magic - #!/bin/bash

11. Add -x to debug 12. Comments - # 13. ; = EOL 14. escapes EOL 15. chmod +x 16. echo $PATH 17. Expansion

VARIABLE=value

All-caps not needed, just recommended

echo ${VARIABLE}

{} not always needed, but stops problems

18. $ is necessary declare -i VARIABLE=value

Specifies variable is an integer

19. Expansion

Math

$[]

20. $(()) Curly-brace expansion

{items,in,list}toexpand

21. {a..z}range 22. Expansion

Command Substitution

$(command)

23. `command` Tilde

~ = your home directory

24. ~user = user's home directory Wildcard globs

man 7 glob

25. Expansion

Prevention

escapes a single special character

26. escapes all but $, ` and 27. '' escapes all special characters 28. Loops

for VAR in items in list; do commands; done

29. exit status - $? 30. test - [ condition ] 31. while [ test ]; do commands; done 32. until [ test ]; do commands; done 33. Conditional Statements

Operators

&&

34. || if [ test ]; then commands 35. elif [ test ]; then commands 36. else commands 37. fi 38. Conditional Statements

case VAR in

39. option)

commands

40. ;; *)

commands

41. ;; esac 42. I/O Redirection

Channel 2 STDERR

2>

43. 2>> Channel 1 - STDOUT

>

44. >> 45. | 46. I/O Redirection

Combining 1 and 2

&>

47. &>> 48. 2>&1 49. >&2 Channel 0 STDIN