Bash Notes For Professionals.100+ pages of professional hints and tricks

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Chapter 1: Getting started with Bash
	Section 1.1: Hello World
	Section 1.2: Hello World Using Variables
	Section 1.3: Hello World with User Input
	Section 1.4: Importance of Quoting in Strings
	Section 1.5: Viewing information for Bash built-ins
	Section 1.6: Hello World in "Debug" mode
	Section 1.7: Handling Named Arguments
Chapter 2: Script shebang
	Section 2.1: Env shebang
	Section 2.2: Direct shebang
	Section 2.3: Other shebangs
Chapter 3: Navigating directories
	Section 3.1: Absolute vs relative directories
	Section 3.2: Change to the last directory
	Section 3.3: Change to the home directory
	Section 3.4: Change to the Directory of the Script
Chapter 4: Listing Files
	Section 4.1: List Files in a Long Listing Format
	Section 4.2: List the Ten Most Recently Modified Files
	Section 4.3: List All Files Including Dotfiles
	Section 4.4: List Files Without Using `ls`
	Section 4.5: List Files
	Section 4.6: List Files in a Tree-Like Format
	Section 4.7: List Files Sorted by Size
Chapter 5: Using cat
	Section 5.1: Concatenate files
	Section 5.2: Printing the Contents of a File
	Section 5.3: Write to a file
	Section 5.4: Show non printable characters
	Section 5.5: Read from standard input
	Section 5.6: Display line numbers with output
	Section 5.7: Concatenate gzipped files
Chapter 6: Grep
	Section 6.1: How to search a file for a pattern
Chapter 7: Aliasing
	Section 7.1: Bypass an alias
	Section 7.2: Create an Alias
	Section 7.3: Remove an alias
	Section 7.4: The BASH_ALIASES is an internal bash assoc array
	Section 7.5: Expand alias
	Section 7.6: List all Aliases
Chapter 8: Jobs and Processes
	Section 8.1: Job handling
	Section 8.2: Check which process running on specific port
	Section 8.3: Disowning background job
	Section 8.4: List Current Jobs
	Section 8.5: Finding information about a running process
	Section 8.6: List all processes
Chapter 9: Redirection
	Section 9.1: Redirecting standard output
	Section 9.2: Append vs Truncate
	Section 9.3: Redirecting both STDOUT and STDERR
	Section 9.4: Using named pipes
	Section 9.5: Redirection to network addresses
	Section 9.6: Print error messages to stderr
	Section 9.7: Redirecting multiple commands to the same file
	Section 9.8: Redirecting STDIN
	Section 9.9: Redirecting STDERR
	Section 9.10: STDIN, STDOUT and STDERR explained
Chapter 10: Control Structures
	Section 10.1: Conditional execution of command lists
	Section 10.2: If statement
	Section 10.3: Looping over an array
	Section 10.4: Using For Loop to List Iterate Over Numbers
	Section 10.5: continue and break
	Section 10.6: Loop break
	Section 10.7: While Loop
	Section 10.8: For Loop with C-style syntax
	Section 10.9: Until Loop
	Section 10.10: Switch statement with case
	Section 10.11: For Loop without a list-of-words parameter
Chapter 11: true, false and : commands
	Section 11.1: Infinite Loop
	Section 11.2: Function Return
	Section 11.3: Code that will always/never be executed
Chapter 12: Arrays
	Section 12.1: Array Assignments
	Section 12.2: Accessing Array Elements
	Section 12.3: Array Modification
	Section 12.4: Array Iteration
	Section 12.5: Array Length
	Section 12.6: Associative Arrays
	Section 12.7: Looping through an array
	Section 12.8: Destroy, Delete, or Unset an Array
	Section 12.9: Array from string
	Section 12.10: List of initialized indexes
	Section 12.11: Reading an entire file into an array
	Section 12.12: Array insert function
Chapter 13: Associative arrays
	Section 13.1: Examining assoc arrays
Chapter 14: Functions
	Section 14.1: Functions with arguments
	Section 14.2: Simple Function
	Section 14.3: Handling flags and optional parameters
	Section 14.4: Print the function definition
	Section 14.5: A function that accepts named parameters
	Section 14.6: Return value from a function
	Section 14.7: The exit code of a function is the exit code of its last command
Chapter 15: Bash Parameter Expansion
	Section 15.1: Modifying the case of alphabetic characters
	Section 15.2: Length of parameter
	Section 15.3: Replace pattern in string
	Section 15.4: Substrings and subarrays
	Section 15.5: Delete a pattern from the beginning of a string
	Section 15.6: Parameter indirection
	Section 15.7: Parameter expansion and filenames
	Section 15.8: Default value substitution
	Section 15.9: Delete a pattern from the end of a string
	Section 15.10: Munging during expansion
	Section 15.11: Error if variable is empty or unset
Chapter 16: Copying (cp)
	Section 16.1: Copy a single file
	Section 16.2: Copy folders
Chapter 17: Find
	Section 17.1: Searching for a file by name or extension
	Section 17.2: Executing commands against a found file
	Section 17.3: Finding file by access / modification time
	Section 17.4: Finding files according to size
	Section 17.5: Filter the path
	Section 17.6: Finding files by type
	Section 17.7: Finding files by specific extension
Chapter 18: Using sort
	Section 18.1: Sort command output
	Section 18.2: Make output unique
	Section 18.3: Numeric sort
	Section 18.4: Sort by keys
Chapter 19: Sourcing
	Section 19.1: Sourcing a file
	Section 19.2: Sourcing a virtual environment
Chapter 20: Here documents and here strings
	Section 20.1: Execute command with here document
	Section 20.2: Indenting here documents
	Section 20.3: Create a file
	Section 20.4: Here strings
	Section 20.5: Run several commands with sudo
	Section 20.6: Limit Strings
Chapter 21: Quoting
	Section 21.1: Double quotes for variable and command substitution
	Section 21.2: Dierence between double quote and single quote
	Section 21.3: Newlines and control characters
	Section 21.4: Quoting literal text
Chapter 22: Conditional Expressions
	Section 22.1: File type tests
	Section 22.2: String comparison and matching
	Section 22.3: Test on exit status of a command
	Section 22.4: One liner test
	Section 22.5: File comparison
	Section 22.6: File access tests
	Section 22.7: Numerical comparisons
Chapter 23: Scripting with Parameters
	Section 23.1: Multiple Parameter Parsing
	Section 23.2: Argument parsing using a for loop
	Section 23.3: Wrapper script
	Section 23.4: Accessing Parameters
	Section 23.5: Split string into an array in Bash
Chapter 24: Bash history substitutions
	Section 24.1: Quick Reference
	Section 24.2: Repeat previous command with sudo
	Section 24.3: Search in the command history by pattern
	Section 24.4: Switch to newly created directory with !#:N
	Section 24.5: Using !$
	Section 24.6: Repeat the previous command with a substitution
Chapter 25: Math
	Section 25.1: Math using dc
	Section 25.2: Math using bash capabilities
	Section 25.3: Math using bc
	Section 25.4: Math using expr
Chapter 26: Bash Arithmetic
	Section 26.1: Simple arithmetic with (( ))
	Section 26.2: Arithmetic command
	Section 26.3: Simple arithmetic with expr
Chapter 27: Scoping
	Section 27.1: Dynamic scoping in action
Chapter 28: Process substitution
	Section 28.1: Compare two files from the web
	Section 28.2: Feed a while loop with the output of a command
	Section 28.3: Concatenating files
	Section 28.4: Stream a file through multiple programs at once
	Section 28.5: With paste command
	Section 28.6: To avoid usage of a sub-shell
Chapter 29: Programmable completion
	Section 29.1: Simple completion using function
	Section 29.2: Simple completion for options and filenames
Chapter 30: Customizing PS1
	Section 30.1: Colorize and customize terminal prompt
	Section 30.2: Show git branch name in terminal prompt
	Section 30.3: Show time in terminal prompt
	Section 30.4: Show a git branch using PROMPT_COMMAND
	Section 30.5: Change PS1 prompt
	Section 30.6: Show previous command return status and time
Chapter 31: Brace Expansion
	Section 31.1: Modifying filename extension
	Section 31.2: Create directories to group files by month and year
	Section 31.3: Create a backup of dotfiles
	Section 31.4: Use increments
	Section 31.5: Using brace expansion to create lists
	Section 31.6: Make Multiple Directories with Sub-Directories
Chapter 32: getopts : smart positional-parameter parsing
	Section 32.1: pingnmap
Chapter 33: Debugging
	Section 33.1: Checking the syntax of a script with "-n"
	Section 33.2: Debugging using bashdb
	Section 33.3: Debugging a bash script with "-x"
Chapter 34: Pattern matching and regular expressions
	Section 34.1: Get captured groups from a regex match against a string
	Section 34.2: Behaviour when a glob does not match anything
	Section 34.3: Check if a string matches a regular expression
	Section 34.4: Regex matching
	Section 34.5: The * glob
	Section 34.6: The ** glob
	Section 34.7: The ? glob
	Section 34.8: The [ ] glob
	Section 34.9: Matching hidden files
	Section 34.10: Case insensitive matching
	Section 34.11: Extended globbing
Chapter 35: Change shell
	Section 35.1: Find the current shell
	Section 35.2: List available shells
	Section 35.3: Change the shell
Chapter 36: Internal variables
	Section 36.1: Bash internal variables at a glance
	Section 36.2: $@
	Section 36.3: $#
	Section 36.4: $HISTSIZE
	Section 36.5: $FUNCNAME
	Section 36.6: $HOME
	Section 36.7: $IFS
	Section 36.8: $OLDPWD
	Section 36.9: $PWD
	Section 36.10: $1 $2 $3 etc..
	Section 36.11: $*
	Section 36.12: $!
	Section 36.13: $?
	Section 36.14: $$
	Section 36.15: $RANDOM
	Section 36.16: $BASHPID
	Section 36.17: $BASH_ENV
	Section 36.18: $BASH_VERSINFO
	Section 36.19: $BASH_VERSION
	Section 36.20: $EDITOR
	Section 36.21: $HOSTNAME
	Section 36.22: $HOSTTYPE
	Section 36.23: $MACHTYPE
	Section 36.24: $OSTYPE
	Section 36.25: $PATH
	Section 36.26: $PPID
	Section 36.27: $SECONDS
	Section 36.28: $SHELLOPTS
	Section 36.29: $_
	Section 36.30: $GROUPS
	Section 36.31: $LINENO
	Section 36.32: $SHLVL
	Section 36.33: $UID
Chapter 37: Job Control
	Section 37.1: List background processes
	Section 37.2: Bring a background process to the foreground
	Section 37.3: Restart stopped background process
	Section 37.4: Run command in background
	Section 37.5: Stop a foreground process
Chapter 38: Case statement
	Section 38.1: Simple case statement
	Section 38.2: Case statement with fall through
	Section 38.3: Fall through only if subsequent pattern(s) match
Chapter 39: Read a file (data stream, variable) line-by-line (and/or field-by-field)?
	Section 39.1: Looping through a file line by line
	Section 39.2: Looping through the output of a command field by field
	Section 39.3: Read lines of a file into an array
	Section 39.4: Read lines of a string into an array
	Section 39.5: Looping through a string line by line
	Section 39.6: Looping through the output of a command line by line
	Section 39.7: Read a file field by field
	Section 39.8: Read a string field by field
	Section 39.9: Read fields of a file into an array
	Section 39.10: Read fields of a string into an array
	Section 39.11: Reads file (/etc/passwd) line by line and field by field
Chapter 40: File execution sequence
	Section 40.1: .profile vs .bash_profile (and .bash_login)
Chapter 41: Splitting Files
	Section 41.1: Split a file
Chapter 42: File Transfer using scp
	Section 42.1: scp transferring file
	Section 42.2: scp transferring multiple files
	Section 42.3: Downloading file using scp
Chapter 43: Pipelines
	Section 43.1: Using |&
	Section 43.2: Show all processes paginated
	Section 43.3: Modify continuous output of a command
Chapter 44: Managing PATH environment variable
	Section 44.1: Add a path to the PATH environment variable
	Section 44.2: Remove a path from the PATH environment variable
Chapter 45: Word splitting
	Section 45.1: What, when and Why?
	Section 45.2: Bad eects of word splitting
	Section 45.3: Usefulness of word splitting
	Section 45.4: Splitting by separator changes
	Section 45.5: Splitting with IFS
	Section 45.6: IFS & word splitting
Chapter 46: Avoiding date using printf
	Section 46.1: Get the current date
	Section 46.2: Set variable to current time
Chapter 47: Using "trap" to react to signals and system events
	Section 47.1: Introduction: clean up temporary files
	Section 47.2: Catching SIGINT or Ctl+C
	Section 47.3: Accumulate a list of trap work to run at exit
	Section 47.4: Killing Child Processes on Exit
	Section 47.5: react on change of terminals window size
Chapter 48: Chain of commands and operations
	Section 48.1: Counting a text pattern ocurrence
	Section 48.2: transfer root cmd output to user file
	Section 48.3: logical chaining of commands with && and ||
	Section 48.4: serial chaining of commands with semicolon
	Section 48.5: chaining commands with |
Chapter 49: Type of Shells
	Section 49.1: Start an interactive shell
	Section 49.2: Detect type of shell
	Section 49.3: Introduction to dot files
Chapter 50: Color script output (cross-platform)
	Section 50.1: color-output.sh
Chapter 51: co-processes
	Section 51.1: Hello World
Chapter 52: Typing variables
	Section 52.1: declare weakly typed variables
Chapter 53: Jobs at specific times
	Section 53.1: Execute job once at specific time
	Section 53.2: Doing jobs at specified times repeatedly using systemd.timer
Chapter 54: Handling the system prompt
	Section 54.1: Using the PROMPT_COMMAND envrionment variable
	Section 54.2: Using PS2
	Section 54.3: Using PS3
	Section 54.4: Using PS4
	Section 54.5: Using PS1
Chapter 55: The cut command
	Section 55.1: Only one delimiter character
	Section 55.2: Repeated delimiters are interpreted as empty fields
	Section 55.3: No quoting
	Section 55.4: Extracting, not manipulating
Chapter 56: Bash on Windows 10
	Section 56.1: Readme
Chapter 57: Cut Command
	Section 57.1: Show the first column of a file
	Section 57.2: Show columns x to y of a file
Chapter 58: global and local variables
	Section 58.1: Global variables
	Section 58.2: Local variables
	Section 58.3: Mixing the two together
Chapter 59: CGI Scripts
	Section 59.1: Request Method: GET
	Section 59.2: Request Method: POST /w JSON
Chapter 60: Select keyword
	Section 60.1: Select keyword can be used for getting input argument in a menu format
Chapter 61: When to use eval
	Section 61.1: Using Eval
	Section 61.2: Using Eval with Getopt
Chapter 62: Networking With Bash
	Section 62.1: Networking commands
Chapter 63: Parallel
	Section 63.1: Parallelize repetitive tasks on list of files
	Section 63.2: Parallelize STDIN
Chapter 64: Decoding URL
	Section 64.1: Simple example
	Section 64.2: Using printf to decode a string
Chapter 65: Design Patterns
	Section 65.1: The Publish/Subscribe (Pub/Sub) Pattern
Chapter 66: Pitfalls
	Section 66.1: Whitespace When Assigning Variables
	Section 66.2: Failed commands do not stop script execution
	Section 66.3: Missing The Last Line in a File
Appendix A: Keyboard shortcuts
	Section A.1: Editing Shortcuts
	Section A.2: Recall Shortcuts
	Section A.3: Macros
	Section A.4: Custome Key Bindings
	Section A.5: Job Control
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