dylanaraps/pure-bash-bible

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Sequence	What does it do?	Value
`\e[38;5;<NUM>m`	Set text foreground color.	`0-255`
`\e[48;5;<NUM>m`	Set text background color.	`0-255`
`\e[38;2;<R>;<G>;<B>m`	Set text foreground color to RGB color.	`R`, `G`, `B`
`\e[48;2;<R>;<G>;<B>m`	Set text background color to RGB color.	`R`, `G`, `B`

Sequence	What does it do?
`\e[m`	Reset text formatting and colors.
`\e[1m`	Bold text.
`\e[2m`	Faint text.
`\e[3m`	Italic text.
`\e[4m`	Underline text.
`\e[5m`	Blinking text.
`\e[7m`	Highlighted text.
`\e[8m`	Hidden text.
`\e[9m`	Strike-through text.

Sequence	What does it do?	Value
`\e[<LINE>;<COLUMN>H`	Move cursor to absolute position.	`line`, `column`
`\e[H`	Move cursor to home position (`0,0`).
`\e[<NUM>A`	Move cursor up N lines.	`num`
`\e[<NUM>B`	Move cursor down N lines.	`num`
`\e[<NUM>C`	Move cursor right N columns.	`num`
`\e[<NUM>D`	Move cursor left N columns.	`num`
`\e[s`	Save cursor position.
`\e[u`	Restore cursor position.

Sequence	What does it do?
`\e[K`	Erase from cursor position to end of line.
`\e[1K`	Erase from cursor position to start of line.
`\e[2K`	Erase the entire current line.
`\e[J`	Erase from the current line to the bottom of the screen.
`\e[1J`	Erase from the current line to the top of the screen.
`\e[2J`	Clear the screen.
`\e[2J\e[H`	Clear the screen and move cursor to `0,0`.

Parameter	What does it do?
`${!VAR}`	Access a variable based on the value of `VAR`.
`${!VAR*}`	Expand to `IFS` separated list of variable names starting with `VAR`.
`${!VAR@}`	Expand to `IFS` separated list of variable names starting with `VAR`. If double-quoted, each variable name expands to a separate word.

Parameter	What does it do?
`${VAR#PATTERN}`	Remove shortest match of pattern from start of string.
`${VAR##PATTERN}`	Remove longest match of pattern from start of string.
`${VAR%PATTERN}`	Remove shortest match of pattern from end of string.
`${VAR%%PATTERN}`	Remove longest match of pattern from end of string.
`${VAR/PATTERN/REPLACE}`	Replace first match with string.
`${VAR//PATTERN/REPLACE}`	Replace all matches with string.
`${VAR/PATTERN}`	Remove first match.
`${VAR//PATTERN}`	Remove all matches.

Parameter	What does it do?
`${#VAR}`	Length of var in characters.
`${#ARR[@]}`	Length of array in elements.

Parameter	What does it do?
`${VAR:OFFSET}`	Remove first `N` chars from variable.
`${VAR:OFFSET:LENGTH}`	Get substring from `N` character to `N` character. (`${VAR:10:10}`: Get sub-string from char `10` to char `20`)
`${VAR:: OFFSET}`	Get first `N` chars from variable.
`${VAR:: -OFFSET}`	Remove last `N` chars from variable.
`${VAR: -OFFSET}`	Get last `N` chars from variable.
`${VAR:OFFSET:-OFFSET}`	Cut first `N` chars and last `N` chars.

Parameter	What does it do?	CAVEAT
`${VAR^}`	Uppercase first character.	`bash 4+`
`${VAR^^}`	Uppercase all characters.	`bash 4+`
`${VAR,}`	Lowercase first character.	`bash 4+`
`${VAR,,}`	Lowercase all characters.	`bash 4+`
`${VAR~}`	Reverse case of first character.	`bash 4+`
`${VAR~~}`	Reverse case of all characters.	`bash 4+`

Parameter	What does it do?
`${VAR:-STRING}`	If `VAR` is empty or unset, use `STRING` as its value.
`${VAR-STRING}`	If `VAR` is unset, use `STRING` as its value.
`${VAR:=STRING}`	If `VAR` is empty or unset, set the value of `VAR` to `STRING`.
`${VAR=STRING}`	If `VAR` is unset, set the value of `VAR` to `STRING`.
`${VAR:+STRING}`	If `VAR` is not empty, use `STRING` as its value.
`${VAR+STRING}`	If `VAR` is set, use `STRING` as its value.
`${VAR:?STRING}`	Display an error if empty or unset.
`${VAR?STRING}`	Display an error if unset.

Expression	Value	What does it do?
`-a`	`file`	If file exists.
`-b`	`file`	If file exists and is a block special file.
`-c`	`file`	If file exists and is a character special file.
`-d`	`file`	If file exists and is a directory.
`-e`	`file`	If file exists.
`-f`	`file`	If file exists and is a regular file.
`-g`	`file`	If file exists and its set-group-id bit is set.
`-h`	`file`	If file exists and is a symbolic link.
`-k`	`file`	If file exists and its sticky-bit is set
`-p`	`file`	If file exists and is a named pipe (FIFO).
`-r`	`file`	If file exists and is readable.
`-s`	`file`	If file exists and its size is greater than zero.
`-t`	`fd`	If file descriptor is open and refers to a terminal.
`-u`	`file`	If file exists and its set-user-id bit is set.
`-w`	`file`	If file exists and is writable.
`-x`	`file`	If file exists and is executable.
`-G`	`file`	If file exists and is owned by the effective group ID.
`-L`	`file`	If file exists and is a symbolic link.
`-N`	`file`	If file exists and has been modified since last read.
`-O`	`file`	If file exists and is owned by the effective user ID.
`-S`	`file`	If file exists and is a socket.

Expression	What does it do?
`file -ef file2`	If both files refer to the same inode and device numbers.
`file -nt file2`	If `file` is newer than `file2` (uses modification time) or `file` exists and `file2` does not.
`file -ot file2`	If `file` is older than `file2` (uses modification time) or `file2` exists and `file` does not.

Expression	Value	What does it do?
`-o`	`opt`	If shell option is enabled.
`-v`	`var`	If variable has a value assigned.
`-R`	`var`	If variable is a name reference.
`-z`	`var`	If the length of string is zero.
`-n`	`var`	If the length of string is non-zero.

Expression	What does it do?
`var = var2`	Equal to.
`var == var2`	Equal to (synonym for `=`).
`var != var2`	Not equal to.
`var < var2`	Less than (in ASCII alphabetical order.)
`var > var2`	Greater than (in ASCII alphabetical order.)

Operators	What does it do?
`+`	Addition
`-`	Subtraction
`*`	Multiplication
`/`	Division
`**`	Exponentiation
`%`	Modulo
`+=`	Plus-Equal (Increment a variable.)
`-=`	Minus-Equal (Decrement a variable.)
`*=`	Times-Equal (Multiply a variable.)
`/=`	Slash-Equal (Divide a variable.)
`%=`	Mod-Equal (Remainder of dividing a variable.)

Operators	What does it do?
`<<`	Bitwise Left Shift
`<<=`	Left-Shift-Equal
`>>`	Bitwise Right Shift
`>>=`	Right-Shift-Equal
`&`	Bitwise AND
`&=`	Bitwise AND-Equal
`\|`	Bitwise OR
`\|=`	Bitwise OR-Equal
`~`	Bitwise NOT
`^`	Bitwise XOR
`^=`	Bitwise XOR-Equal

Operators	What does it do?
`!`	NOT
`&&`	AND
`\|\|`	OR

pure bash bible

Table of Contents

FOREWORD

STRINGS

Trim leading and trailing white-space from string

Trim all white-space from string and truncate spaces

Use regex on a string

Split a string on a delimiter

Change a string to lowercase

Change a string to uppercase

Reverse a string case

Trim quotes from a string

Strip all instances of pattern from string

Strip first occurrence of pattern from string

Strip pattern from start of string

Strip pattern from end of string

Percent-encode a string

Decode a percent-encoded string

Check if string contains a sub-string

Check if string starts with sub-string

Check if string ends with sub-string

ARRAYS

Reverse an array

Remove duplicate array elements

Random array element

Cycle through an array

Toggle between two values

LOOPS

Loop over a range of numbers

Loop over a variable range of numbers

Loop over an array

Loop over an array with an index

Loop over the contents of a file

Loop over files and directories

FILE HANDLING

Read a file to a string

Read a file to an array (by line)

Get the first N lines of a file

Get the last N lines of a file

Get the number of lines in a file

Count files or directories in directory

Create an empty file

Extract lines between two markers

FILE PATHS

Get the directory name of a file path

Get the base-name of a file path

VARIABLES

Assign and access a variable using a variable

Name a variable based on another variable

ESCAPE SEQUENCES

Text Colors

Text Attributes

Cursor Movement

Erasing Text

PARAMETER EXPANSION

Indirection

Replacement

Length

Expansion

Case Modification

Default Value

BRACE EXPANSION

Ranges

String Lists

CONDITIONAL EXPRESSIONS

File Conditionals

File Comparisons

Variable Conditionals

Variable Comparisons

ARITHMETIC OPERATORS

Assignment

Arithmetic

Bitwise

Logical

Miscellaneous

ARITHMETIC

Simpler syntax to set variables

Ternary Tests

TRAPS

Do something on script exit

Get the location to the `bash` binary

Get the version of the current running `bash` process

Shorter `for` loop syntax

Shorter `if` syntax

Simpler `case` statement to set variable

Use `read` as an alternative to the `sleep` command

Get the current date using `strftime`