Mastering Bash

Table of contents

1. Preface
   1. What this book covers
   2. What you need for this book
   3. Who this book is for
   4. Conventions
   5. Reader feedback
   6. Customer support
      1. Downloading the example code
      2. Downloading the color images of this book
      3. Errata
      4. Piracy
      5. Questions
2. Let's Start Programming
   1. I/O redirection
   2. Messing around with stdin, stdout, and stderr
   3. Time for the interpreter: the sha-bang
      1. Calling your script
      2. Something went wrong, let's trace it
   4. Variables
      1. Assigning a variable
      2. Keep the variable name safe
      3. Variables with limited scope
      4. Environment variables
      5. Variable expansion
      6. Pattern matching against variables
      7. Special variables
   5. Summary
3. Operators
   1. Arithmetic operators
      1. The + operator
      2. The - operator
      3. The * operator
      4. The / operator
      5. The % operator
      6. The ** operator
   2. Assignment operators
      1. The += operator
      2. The -= operator
      3. The *= operator
      4. The /= operator
      5. The %= operator
      6. The ++ or -- operators
   3. Bitwise operators
      1. Left shift (<<)
      2. Right shift (>>)
      3. Bitwise AND
      4. Bitwise OR (|)
      5. Bitwise XOR (^)
      6. Bitwise NOT (~)
   4. Logical operators
      1. Logical NOT (!)
      2. Logical AND
      3. Logical OR (||)
   5. Comma operator (,)
   6. Operators evaluation order and precedence in decreasing relevance
   7. Exit codes
      1. Exiting a script
   8. Summary
4. Testing
   1. What if...else
   2. Test command recap
      1. Testing files
      2. Testing integers
      3. Testing strings
      4. More on tests
   3. Summary
5. Quoting and Escaping
   1. Special characters
      1. The hash character (#)
      2. The semicolon character (;)
      3. The double semicolon character (;;)
      4. The case terminator (;;&) and (;&))
      5. The dot character (.)
      6. The double quotes ("...")
      7. The single quotes ('...')
      8. The comma character (,)
      9. The ,, and , () case modificators
      10. The ^^ and ^ () case modificators
      11. The backslash (\)
      12. The forward slash (/)
      13. '...'
      14. The colon character (:)
      15. The exclamation (!)
      16. Keywords
      17. The asterisk (*)
      18. The double asterisk (**)
      19. Test operators (?)
      20. The substitution ($)
      21. The parameter substitution (${})
      22. The quoted string expansion ($'...')
      23. The positional parameters ($* and $")
      24. The exit status ($?)
      25. The process ID ($$)
      26. Grouping the command (command1 ; command2 ; commandn)
      27. Braces ({})
      28. The full path ({} \;)
      29. Expression ([])
      30. Expression ([[]])
      31. The array index ([])
      32. Characters range ([])
      33. Integer expansion ($[…])
      34. Integer expansion (((..)))
      35. DEMO
          1. The here document (<<)
          2. The here string (<<<)
          3. The ASCII comparison operators (<) and (>)
      36. Delimiters (\< and \>)
      37. The pipe character (|)
      38. The force redirection (>|)
      39. The logical OR (||)
      40. DEMO
      41. Logical AND
      42. The dash character (-)
      43. The double dash (--)
      44. Operator =
      45. Operator +
      46. The modulo operator (%)
      47. Operator ~
      48. Operator ~+
      49. Operator ~-
      50. Operator ~=
      51. Operator ^
      52. The control characters (^ and ^^)
   2. Quoting and escaping
      1. The backslash (\)
      2. Double quotes ("")
      3. Single quotes (')
   3. Summary
6. Menus, Arrays, and Functions
   1. The case statement
   2. Arrays
   3. Functions
   4. Summary
7. Iterations
   1. The for loop
   2. Let's do something while, until…
   3. Exiting the loop with break and continue
   4. Time to give our client a menu
   5. CLI, passing the arguments to the command line
   6. Summary
8. Plug into the Real World
   1. What is Nagios?
   2. Active and passive checks
      1. Active checks
      2. Passive checks
   3. Returning code and thresholds
   4. Command and service definitions
   5. Our first Nagios plugin
   6. Summary
9. We Want to Chat
   1. The Slack messaging service
   2. Slack WebHooks
   3. What is a JSON?
   4. Do you like cURLing?
   5. Formatting our messages
   6. Message attachments
   7. Our wee chatty script for Slack
   8. Summary
10. Subshells, Signals, and Job Controls
    1. What is a subshell?
    2. Background processes
    3. Signals
    4. Job controls
    5. Subshells and parallel processing
    6. Summary
11. Lets Make a Process Chat
    1. Pipes
    2. Redirection to a file
    3. The command substitution
    4. The process substitution
    5. Environment variables
    6. Coprocesses
    7. /dev/tcp and /dev/udp
    8. Netcat
    9. Summary
12. Living as a Daemon
    1. What is a daemon?
    2. DEMO
       1. nohup
    3. disown
    4. Double fork and setsid
    5. Becoming a daemon
    6. Trapping a daemon
    7. Going dark with the daemon
    8. Summary
13. Remote Connections over SSH
    1. What is SSH?
    2. Configuration files
    3. The sshd_config file
    4. ssh_config
    5. Passwordless connections
       1. Configuring the server
       2. Preparing the remote account
       3. Configuring the client
    6. Proxies and tunnels
    7. Summary
14. Its Time for a Timer
    1. One shot at it
    2. The cron scheduler
       1. cron
    3. Summary
15. Time for Safety
    1. The restricted shell
       1. Restricted shells for OpenSSH
    2. Restricted sftp sessions with OpenSSH
    3. Summary