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about_PSReadline



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about_PSReadline
TOPIC
about_PSReadline

SHORT DESCRIPTION

PSReadline provides an improved command line editing experience in
the Windows PowerShell console.

LONG DESCRIPTION

PSReadline, introduced in Windows PowerShell 5.0, provides a powerful
command line editing experience for the Windows PowerShell console.
It provides:

* Syntax coloring of the command line
* A visual indication of syntax errors
* A better multi-line experience (both editing and history)
* Customizable key bindings
* Cmd and Emacs modes
* Many configuration options
* Bash style completion (optional in Cmd mode, default in Emacs mode)
* Emacs yank/kill ring
* Windows PowerShell token based "word" movement and kill

The following functions are available in the class [PSConsoleUtilities.PSConsoleReadLine]:

Cursor movement
---------------

EndOfLine (Cmd: <End> Emacs: <End> or <Ctrl+E>)

If the input has multiple lines, move to the end of the current line,
or if already at the end of the line, move to the end of the input.
If the input has a single line, move to the end of the input.

BeginningOfLine (Cmd: <Home> Emacs: <Home> or <Ctrl+A>)

If the input has multiple lines, move to the start of the current line,
or if already at the start of the line, move to the start of the input.
If the input has a single line, move to the start of the input.

NextLine (Cmd: unbound Emacs: unbound)

Move the cursor to the next line if the input has multiple lines.

PreviousLine (Cmd: unbound Emacs: unbound)

Move the cursor to the previous line if the input has multiple lines.

ForwardChar (Cmd: <RightArrow> Emacs: <RightArrow> or <Ctrl+F>)

Move the cursor one character to the right. This might move the cursor to the next
line of multi-line input.

BackwardChar (Cmd: <LeftArrow> Emacs: <LeftArrow> or <Ctrl+B>)

Move the cursor one character to the left. This might move the cursor to the previous
line of multi-line input.

ForwardWord (Cmd: unbound Emacs: <Alt+F>)

Move the cursor forward to the end of the current word, or if between words,
to the end of the next word. You can set word delimiter characters with:

Set-PSReadlineOption -WordDelimiters <string of delimiter characters>

NextWord (Cmd: <Ctrl+RightArrow> Emacs: unbound)

Move the cursor forward to the start of the next word. You can set word
delimiter characters with:

Set-PSReadlineOption -WordDelimiters <string of delimiter characters>

BackwardWord (Cmd: <Ctrl+LeftArrow> Emacs: <Alt+B>)

Move the cursor back to the start of the current word, or if between words,
the start of the previous word. You can set word delimiter characters with:

Set-PSReadlineOption -WordDelimiters <string of delimiter characters>

ShellForwardWord (Cmd: unbound Emacs: unbound)

Like ForwardWord except word boundaries are defined by Windows PowerShell
token boundaries.

ShellNextWord (Cmd: unbound Emacs: unbound)

Like NextWord except word boundaries are defined by Windows PowerShell
token boundaries.

ShellBackwardWord (Cmd: unbound Emacs: unbound)

Like BackwardWord except word boundaries are defined by Windows PowerShell
token boundaries.

GotoBrace (Cmd: <Ctrl+}> Emacs: unbound)

Go to the matching parenthesis, curly brace, or square bracket.

AddLine (Cmd: <Shift-Enter> Emacs: <Shift-Enter>)

The continuation prompt is displayed on the next line and PSReadline waits for
keys to edit the current input. This is useful to enter multi-line input as
a single command even when a single line is complete input by itself.

Basic editing
-------------

CancelLine (Cmd: unbound Emacs: unbound)

Cancel all editing to the line, leave the line of input on the screen but
return from PSReadline without executing the input.

RevertLine (Cmd: <ESC> Emacs: <Alt+R>)

Reverts all of the input since the last input was accepted and run.
This is equivalent to using the Undo command until there is nothing
left to undo.



BackwardDeleteChar (Cmd: <Backspace> Emacs: <Backspace> or <Ctrl+H>)

Delete the character before the cursor.

DeleteChar (Cmd: <Delete> Emacs: <Delete>)

Delete the character under the cursor.

DeleteCharOrExit (Cmd: unbound Emacs: <Ctrl+D>)

Like DeleteChar, unless the line is empty, in which case exit the process.

AcceptLine (Cmd: <Enter> Emacs: <Enter> or <Ctrl+M>)

Attempt to execute the current input. If the current input is incomplete (for
example, there is a missing closing parenthesis, bracket, or quote), then the
continuation prompt is displayed on the next line, and PSReadline waits for
keys to edit the current input.

AcceptAndGetNext (Cmd: unbound Emacs: <Ctrl+O>)

Like AcceptLine, but after the line completes, start editing the next line
from history.

ValidateAndAcceptLine (Cmd: unbound Emacs: unbound)

Like AcceptLine but performs additional validation including:

* Checks for additional parse errors
* Validates that command names are all found
* If you are running Windows PowerShell 4.0 or newer,
validates the parameters and arguments

If there are any errors, the error message is displayed and not accepted nor added
to the history unless you either correct the command line or execute AcceptLine or
ValidateAndAcceptLine again while the error message is displayed.

BackwardDeleteLine (Cmd: <Ctrl+Home> Emacs: unbound)

Delete the text from the start of the input to the cursor.

ForwardDeleteLine (Cmd: <Ctrl+End> Emacs: unbound)

Delete the text from the cursor to the end of the input.

SelectBackwardChar (Cmd: <Shift+LeftArrow> Emacs: <Shift+LeftArrow>)

Adjust the current selection to include the previous character.

SelectForwardChar (Cmd: <Shift+RightArrow> Emacs: <Shift+RightArrow>)

Adjust the current selection to include the next character.

SelectBackwardWord (Cmd: <Shift+Ctrl+LeftArrow> Emacs: <Alt+Shift+B>)

Adjust the current selection to include the previous word.

SelectForwardWord (Cmd: unbound Emacs: <Alt+Shift+F>)

Adjust the current selection to include the next word using ForwardWord.

SelectNextWord (Cmd: <Shift+Ctrl+RightArrow> Emacs: unbound)

Adjust the current selection to include the next word using NextWord.

SelectShellForwardWord (Cmd: unbound Emacs: unbound)

Adjust the current selection to include the next word using ShellForwardWord.

SelectShellNextWord (Cmd: unbound Emacs: unbound)

Adjust the current selection to include the next word using ShellNextWord.

SelectShellBackwardWord (Cmd: unbound Emacs: unbound)

Adjust the current selection to include the previous word using ShellBackwardWord.

SelectBackwardsLine (Cmd: <Shift+Home> Emacs: <Shift+Home>)

Adjust the current selection to include from the cursor to the start of the line.

SelectLine (Cmd: <Shift+End> Emacs: <Shift+End>)

Adjust the current selection to include from the cursor to the end of the line.

SelectAll (Cmd: <Ctrl+A> Emacs: unbound)

Select the entire line. Moves the cursor to the end of the line.

SelfInsert (Cmd: <a>, <b>, ... Emacs: <a>, <b>, ...)

Insert the key entered.

Redo (Cmd: <Ctrl+Y> Emacs: unbound)

Redo an insertion or deletion that was undone by Undo.

Undo (Cmd: <Ctrl+Z> Emacs: <Ctrl+_>)

Undo a previous insertion or deletion.

History
-------

ClearHistory (Cmd: Alt+F7 Emacs: unbound)

Clears history in PSReadline. This does not affect Windows PowerShell
history.

PreviousHistory (Cmd: <UpArrow> Emacs: <UpArrow> or <Ctrl+P>)

Replace the current input with the previous item from PSReadline history.

NextHistory (Cmd: <DownArrow> Emacs: <DownArrow> or <Ctrl+N>)

Replace the current input with the next item from PSReadline history.

ForwardSearchHistory (Cmd: <Ctrl+S> Emacs: <Ctrl+S>)

Search forward from the current history line interactively.



ReverseSearchHistory (Cmd: <Ctrl+R> Emacs: <Ctrl+R>)

Search backward from the current history line interactively.

HistorySearchBackward (Cmd: <F8> Emacs: unbound)

Replace the current input with the previous item from PSReadline history
that matches the characters between the start and the input and the cursor.

HistorySearchForward (Cmd: <Shift+F8> Emacs: unbound)

Replace the current input with the next item from PSReadline history
that matches the characters between the start and the input and the cursor.

BeginningOfHistory (Cmd: unbound Emacs: <Alt+<>)

Replace the current input with the last item from PSReadline history.

EndOfHistory (Cmd: unbound Emacs: <Alt+>>)

Replace the current input with the last item in PSReadline history, which
is the possibly empty input that was entered before any history commands.

Tab Completion
--------------

TabCompleteNext (Cmd: <Tab> Emacs: unbound)

Attempt to complete the text surrounding the cursor with the next
available completion.

TabCompletePrevious (Cmd: <Shift-Tab> Emacs: unbound)

Attempt to complete the text surrounding the cursor with the next
previous completion.

Complete (Cmd: unbound Emacs: <Tab>)

Attempt to perform completion on the text surrounding the cursor.
If there are multiple possible completions, the longest unambiguous
prefix is used for completion. If you are trying to complete the longest
unambiguous completion, a list of possible completions is displayed.

MenuComplete (Cmd: <Ctrl+Space> Emacs: <Ctrl+Space>)

Attempt to perform completion on the text surrounding the cursor.
If there are multiple possible completions, a list of possible
completions is displayed, and you can select the correct completion
by using the arrow keys, or Tab/Shift+Tab. Escape and Ctrl+G cancel
the menu selection, and revert the line to the state before invoking
MenuComplete.

PossibleCompletions (Cmd: unbound Emacs: <Alt+Equals>)

Display the list of possible completions.

SetMark (Cmd: unbound Emacs: <Alt+Space>)

Mark the current location of the cursor for use in a subsequent editing command.

ExchangePointAndMark (Cmd: unbound Emacs: <Ctrl+X,Ctrl+X>)

The cursor is placed at the location of the mark and the mark is moved
to the location of the cursor.

Kill/Yank
---------

Kill and Yank operate on a clipboard in the PSReadline module. There is a ring
buffer called the kill ring - killed text is added to the kill ring up
and yank will copy text from the most recent kill. YankPop cycles through
items in the kill ring. When the kill ring is full, new items replace the
oldest items. A kill operation that is immediately preceded by another kill operation
appends the previous kill, instead of adding a new item or replacing an item
in the kill ring. This is how you can cut a part of a line, for example, with multiple
KillWord operations, then yank them back elsewhere as a single yank.

KillLine (Cmd: unbound Emacs: <Ctrl+K>)

Clear the input from the cursor to the end of the line. The cleared text is placed
in the kill ring.

BackwardKillLine (Cmd: unbound Emacs: <Ctrl+U> or <Ctrl+X,Backspace>)

Clear the input from the start of the input to the cursor. The cleared text is placed
in the kill ring.

KillWord (Cmd: unbound Emacs: <Alt+D>)

Clear the input from the cursor to the end of the current word. If the cursor
is between words, the input is cleared from the cursor to the end of the next word.
The cleared text is placed in the kill ring.

BackwardKillWord (Cmd: unbound Emacs: <Alt+Backspace>)

Clear the input from the start of the current word to the cursor. If the cursor
is between words, the input is cleared from the start of the previous word to the
cursor. The cleared text is placed in the kill ring.

ShellKillWord (Cmd: unbound Emacs: unbound)

Like KillWord, except word boundaries are defined by Windows PowerShell
token boundaries.

ShellBackwardKillWord (Cmd: unbound Emacs: unbound)

Like BackwardKillWord, except word boundaries are defined by Windows PowerShell
token boundaries.

UnixWordRubout (Cmd: unbound Emacs: <Ctrl+W>)

Like BackwardKillWord, except word boundaries are defined by white space.

KillRegion (Cmd: unbound Emacs: unbound)

Kill the text between the cursor and the mark.

Copy (Cmd: <Ctrl+Shift+C> Emacs: unbound)

Copy selected region to the system clipboard. If no region is selected, copy the whole line.

CopyOrCancelLine (Cmd: <Ctrl+C> Emacs: <Ctrl+C>)

Either copy selected text to the clipboard, or if no text is selected, cancel editing
the line with CancelLine.

Cut (Cmd: <Ctrl+X> Emacs: unbound)

Delete selected region placing deleted text in the system clipboard.

Yank (Cmd: unbound Emacs: <Ctrl+Y>)

Add the most-recently killed text to the input.

YankPop (Cmd: unbound Emacs: <Alt+Y>)

If the previous operation was Yank or YankPop, replace the previously-yanked
text with the next killed text from the kill ring.

ClearKillRing (Cmd: unbound Emacs: unbound)

The contents of the kill ring are cleared.

Paste (Cmd: <Ctrl+V> Emacs: unbound)

This is similar to Yank, but uses the system clipboard instead of the kill ring.

YankLastArg (Cmd: <Alt+.> Emacs: <Alt+.>, <Alt+_>)

Insert the last argument from the previous command in history. Repeated operations
replace the last inserted argument with the last argument from the previous
command (so Alt+. Alt+. will insert the last argument of the second to last history
line).

With an argument, the first time YankLastArg behaves like YankNthArg. A negative
argument on subsequent YankLastArg calls changes the direction while going
through history. For example, if you press Alt+. one too many times, you can type
Alt+- Alt+. to reverse the direction.

Arguments are based on Windows PowerShell tokens.

YankNthArg (Cmd: unbound Emacs: <Alt+Ctrl+Y>)

Insert the first argument (not the command name) of the previous command in history.

With an argument, insert the nth argument where 0 is typically the command. Negative
arguments start from the end.

Arguments are based on Windows PowerShell tokens.

Miscellaneous
-------------

Abort (Cmd: unbound Emacs: <Ctrl+G>)

Abort the current action; for example, stop interactive history search.
Does not cancel input like CancelLine.

CharacterSearch (Cmd: <F3> Emacs: <Ctrl+]>)

Read a key and search forwards for that character. With an argument, search
forwards for the nth occurrence of that argument. With a negative argument,
searches backwards.

CharacterSearchBackward (Cmd: <Shift+F3> Emacs: <Alt+Ctrl+]>)

Like CharacterSearch, but searches backwards. With a negative argument, searches
forwards.

ClearScreen (Cmd: <Ctrl+L> Emacs: <Ctrl+L>)

Clears the screen and displays the current prompt and input at the top of the screen.

DigitArgument (Cmd: unbound Emacs: <Alt+[0..9]>,,<Alt+->)

Used to pass numeric arguments to functions like CharacterSearch or YankNthArg.
Alt+- toggles the argument to be negative/non-negative. To enter 80 '*' characters,
you could type Alt+8 Alt+0 *.

CaptureScreen (Cmd: unbound Emacs: unbound)

Copies selected lines to the clipboard in both text and RTF formats. Use up/down
arrow keys to the first line to select, then Shift+UpArrow/Shift+DownArrow to select
multiple lines. After selecting, press Enter to copy the text. Escape/Ctrl+C/Ctrl+G
cancel the operation, so nothing is copied to the clipboard.

InvokePrompt (Cmd: unbound Emacs: unbound)

Erases the current prompt and calls the prompt function to redisplay
the prompt. Useful for custom key handlers that change state, such as
changing the current directory.

WhatIsKey (Cmd: <Alt+?> Emacs: <Alt+?>)

Read a key or chord and display the key binding.

ShowKeyBindings (Cmd: <Ctrl+Alt+?> Emacs: <Ctrl+Alt+?>)

Show all of the currently-bound keys.

ScrollDisplayUp (Cmd: <PageUp> Emacs: <PageUp>)

Scroll the display up one screen.

ScrollDisplayUpLine (Cmd: <Ctrl+PageUp> Emacs: <Ctrl+PageUp>)

Scroll the display up one line.

ScrollDisplayDown (Cmd: <PageDown> Emacs: <PageDown>)

Scroll the display down one screen.

ScrollDisplayDownLine (Cmd: <Ctrl+PageDown> Emacs: <Ctrl+PageDown>)

Scroll the display down one line.

ScrollDisplayTop (Cmd: unbound Emacs: <Ctrl+Home>)

Scroll the display to the top.

ScrollDisplayToCursor (Cmd: unbound Emacs: <Ctrl+End>)

Scroll the display to the cursor.

Custom Key Bindings
-------------------

PSReadline supports custom key bindings using the cmdlet Set-PSReadlineKeyHandler. Most
custom key bindings call one of the above functions, for example:

Set-PSReadlineKeyHandler -Key UpArrow -Function HistorySearchBackward

You can bind a ScriptBlock to a key. The ScriptBlock can do virtually anything you want.
Some useful examples include:

* edit the command line
* opening a new window (e.g. help)
* change directories without changing the command line

The ScriptBlock is passed two arguments:

* $key - A [ConsoleKeyInfo] that is the key that triggered the custom binding. If you bind
the same ScriptBlock to multiple keys and need to perform different actions depending
on the key, you can check $key. Many custom bindings ignore this argument.
* $arg - An arbitrary argument. Most often, this would be an integer argument that the user
passes from the key bindings DigitArgument. If your binding doesn't accept arguments,
it's reasonable to ignore this argument.

Let's take a look at an example that adds a command line to history without executing it. This is
useful when you realize you forgot to do something, but don't want to re-enter the command line
you've already entered.

Set-PSReadlineKeyHandler -Key Alt+w `
-BriefDescription SaveInHistory `
-LongDescription "Save current line in history but do not execute" `
-ScriptBlock {
param($key, $arg) # The arguments are ignored in this example

# We need the command line, GetBufferState gives us that (with the cursor position)
$line = $null
$cursor = $null
[PSConsoleUtilities.PSConsoleReadLine]::GetBufferState([ref]$line, [ref]$cursor)

# AddToHistory saves the line in history, but does not execute the line.
[PSConsoleUtilities.PSConsoleReadLine]::AddToHistory($line)

# RevertLine is like pressing Escape.
[PSConsoleUtilities.PSConsoleReadLine]::RevertLine()
}

You can see many more examples in the file SamplePSReadlineProfile.ps1 which is installed in the
PSReadline module folder.

Most key bindings will want to take advantage of some helper functions for editing the command
line those APIs are documented in the next section.

Custom Key Binding Support APIs
-------------------------------

The following functions are public in PSConsoleUtilities.PSConsoleReadline, but cannot be directly
bound to a key. Most are useful in custom key bindings.

void AddToHistory(string command)

Add a command line to history without executing it.

void ClearKillRing()

Clear the kill ring. This is mostly used for testing.

void Delete(int start, int length)

Delete length characters from start. This operation supports undo and redo.

void Ding()

Perform the Ding action based on the user’s preference.

void GetBufferState([ref] string input, [ref] int cursor)
void GetBufferState([ref] Ast ast, [ref] Token[] tokens, [ref] ParseError[] parseErrors, [ref] int cursor)

These two functions retrieve useful information about the current state of
the input buffer. The first is more commonly used for simple cases. The
second is used if your binding is doing something more advanced with the Ast.

IEnumerable[PSConsoleUtilities.KeyHandler] GetKeyHandlers(bool includeBound, bool includeUnbound)

This function is used by Get-PSReadlineKeyHandler and probably isn't useful in a custom
key binding.

PSConsoleUtilities.PSConsoleReadlineOptions GetOptions()

This function is used by Get-PSReadlineOption and probably isn't too useful in a custom
key binding.

void GetSelectionState([ref] int start, [ref] int length)

If there is no selection on the command line, -1 is returned in both start and length.
If there is a selection on the command line, the start and length of the selection are returned.

void Insert(char c)
void Insert(string s)

Insert a character or string at the cursor. This operation supports undo and redo.

string ReadLine(runspace remoteRunspace, System.Management.Automation.EngineIntrinsics engineIntrinsics)

This is the main entry point to PSReadline. It does not support recursion, so is not useful
in a custom key binding.

void RemoveKeyHandler(string[] key)

This function is used by Remove-PSReadlineKeyHandler and probably isn't too useful in a
custom key binding.

void Replace(int start, int length, string replacement)

Replace some of the input. This operation supports undo and redo.
This is preferred over Delete followed by Insert because it is treated as a single action
for undo.

void SetCursorPosition(int cursor)

Move the cursor to the given offset. Cursor movement is not tracked for undo.

void SetOptions(PSConsoleUtilities.SetPSReadlineOption options)

This function is a helper method used by the cmdlet Set-PSReadlineOption, but might be
useful to a custom key binding that wants to temporarily change a setting.

bool TryGetArgAsInt(System.Object arg, [ref] int numericArg, int defaultNumericArg)

This helper method is used for custom bindings that honor DigitArgument. A typical call
looks like:

[int]$numericArg = 0
[PSConsoleUtilities.PSConsoleReadLine]::TryGetArgAsInt($arg, [ref]$numericArg, 1)

WINDOWS POWERSHELL COMPATIBILITY

PSReadline requires Windows PowerShell 3.0 or newer, and the console host. It
does not work in Windows PowerShell ISE.

FEEDBACK

https://github.com/lzybkr/PSReadline

CONTRIBUTING TO PSREADLINE

Feel free to submit a pull request or submit feedback on the PSReadline
GitHub page (https://github.com/lzybkr/PSReadLine).

SEE ALSO

PSReadline is heavily influenced by the GNU Readline library:
http://tiswww.case.edu/php/chet/readline/rltop.html

Get-PSReadlineKeyHandler
Get-PSReadlineOption
Remove-PSReadlineKeyHandler
Set-PSReadlineKeyHandler
Set-PSReadlineOption