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Simplistic interactive filtering tool

NOTE: If you are viewing this on Github, this document refers to the state of peco in whatever current branch you are viewing, not necessarily the state of a currently released version. Please make sure to checkout the Changes file for features and changes.

This README is long and comprehensive. Use the Table of Contents to navigate to the section that interests you. It has been placed at the bottom of the README file because of its length.


peco (pronounced peh-koh) is based on a python tool, percol. percol was darn useful, but I wanted a tool that was a single binary, and forget about python. peco is written in Go, and therefore you can just grab the binary releases and drop it in your $PATH.

peco can be a great tool to filter stuff like logs, process stats, find files, because unlike grep, you can type as you think and look through the current results.

For basic usage, continue down below. For more cool elaborate usage samples, please see the wiki, and if you have any other tricks you want to share, please add to it!


Demos speak more than a thousand words! Here's me looking for a process on my mac. As you can see, you can page through your results, and you can keep changing the query:

Executed `ps -ef | peco`, then the query `root` was typed. This shows all lines containing the word root

Here's me trying to figure out which file to open:

Executed `find . -name '*.go' | peco` (within camlistore repository), then the query `camget` was typed. This shows all lines including the word `camget`

When you combine tools like zsh, peco, and ghq, you can make managing/moving around your huge dev area a piece of cake! (this example doesn't use zsh functions so you can see what I'm doing)

Executed `cd $(ghq list --full-path | peco --query peco)` to show all repositories containing the word `peco`, then to change directories into the one selected


Incremental Search

Search results are filtered as you type. This is great to drill down to the line you are looking for

Multiple terms turn the query into an "AND" query:

Executed `ps aux | peco`, then the query `root app` was typed. This shows all lines containing both `root` and `app`

When you find that line that you want, press enter, and the resulting line is printed to stdout, which allows you to pipe it to other tools

Select Multiple Lines

You can select multiple lines!

Executed `ls -l | peco`, then used peco.ToggleSelection to select multiple lines

Select Range Of Lines

Not only can you select multiple lines one by one, you can select a range of lines (Note: The ToggleRangeMode action is not enabled by default. You need to put a custom key binding in your config file)

Executed `ps -ef | peco`, then used peco.ToggleRangeMode to select a range of lines

Select Filters

Different types of filters are available. Default is case-insensitive filter, so lines with any case will match. You can toggle between IgnoreCase, CaseSensitive, SmartCase RegExp and Fuzzy filters.

The SmartCase filter uses case-insensitive matching when all of the queries are lower case, and case-sensitive matching otherwise.

The RegExp filter allows you to use any valid regular expression to match lines

The Fuzzy filter allows you to find matches using partial patterns. For example, when searching for ALongString, you can enable the Fuzzy filter and search ALS to find it. The Fuzzy filter uses smart case search like the SmartCase filter.

Executed `ps aux | peco`, then typed `google`, which matches the under IgnoreCase filter type. When you change it to Regexp filter, this is no longer the case. But you can type `(?i)google` instead to toggle case-insensitive mode

Selectable Layout

As of v0.2.5, if you would rather not move your eyes off of the bottom of the screen, you can change the screen layout by either providing the --layout=bottom-up command line option, or set the Layout variable in your configuration file

Executed `ps -ef | peco --layout=bottom-up` to toggle inverted layout mode

Works on Windows!

I have been told that peco even works on windows :) Look ma! I'm not lying!

Showing peco running on Windows cmd.exe


Just want the binary?

Go to the releases page, find the version you want, and download the zip file. Unpack the zip file, and put the binary to somewhere you want (on UNIX-y systems, /usr/local/bin or the like). Make sure it has execution bits turned on. Yes, it is a single binary! You can put it anywhere you want :)

THIS IS THE RECOMMENDED WAY (except for OS X homebrew users)

Mac OS X / Homebrew

If you're on OS X and want to use homebrew:

brew install peco

Windows (Chocolatey NuGet Users)

There's a third-party peco package available for Chocolatey NuGet.

C:\> choco install peco

Building peco yourself

From the root of your cloned peco repository, run:

glide install

This installs the correct versions of peco's dependencies. Then build it:

go build cmd/peco/peco.go

This compiles a peco binary in the root of the cloned peco repository. Copy this file to an appropriate location.


Please DO NOT use go get to install this tool. It bypasses the developers' intention of controlling the dependency versioning.

Command Line Options

-h, --help

Display a help message


Display the version of peco


Specifies the default query to be used upon startup. This is useful for scripts and functions where you can figure out before hand what the most likely query string is.


Pass peco a configuration file, which currently must be a JSON file. If unspecified it will try a series of files by default. See Configuration File for the actual locations searched.

-b, --buffer-size

Limits the buffer size to num. This is an important feature when you are using peco against a possibly infinite stream, as it limits the number of lines that peco holds at any given time, preventing it from exhausting all the memory. By default the buffer size is unlimited.


WARNING: EXPERIMENTAL. This feature will probably stay, but the option name may change in the future.

Changes how peco interprets incoming data. When this flag is set, you may insert NUL ('\0') characters in your input. Anything before the NUL character is treated as the string to be displayed by peco and is used for matching against user query. Anything after the NUL character is used as the "result": i.e., when peco is about to exit, it displays this string instead of the original string displayed.

Here's a simple example of how to use this feature


Specifies the initial line position upon start up. E.g. If you want to start out with the second line selected, set it to "1" (because the index is 0 based)

--initial-filter IgnoreCase|CaseSensitive|SmartCase|Regexp|Fuzzy

Specifies the initial filter to use upon start up. You should specify the name of the filter like IgnoreCase, CaseSensitive, SmartCase, Regexp and Fuzzy. Default is IgnoreCase.


Specifies the query line's prompt string. When specified, takes precedence over the configuration file's Prompt section. The default value is QUERY>

--layout top-down|bottom-up

Specifies the display layout. Default is top-down, where query prompt is at the top, followed by the list, then the system status message line. bottom-up changes this to the list first (displayed in reverse order), the query prompt, and then the system status message line.

For percol users, --layout=bottom-up is almost equivalent of --prompt-bottom --result-bottom-up.


When specified and the input contains exactly 1 line, peco skips prompting you for a choice, and selects the only line in the input and immediately exits.

If there are multiple lines in the input, the usual selection view is displayed.

--on-cancel success|error

Specifies the exit status to use when the user cancels the query execution. For historical and back-compatibility reasons, the default is success, meaning if the user cancels the query, the exit status is 0. When you choose error, peco will exit with a non-zero value.

Configuration File

peco by default consults a few locations for the config files.

  1. Location specified in --rcfile. If this doesn't exist, peco complains and exits
  2. $XDG_CONFIG_HOME/peco/config.json
  3. $HOME/.config/peco/config.json
  4. for each directories listed in $XDG_CONFIG_DIRS, $DIR/peco/config.json
  5. If all else fails, $HOME/.peco/config.json

Below are configuration sections that you may specify in your config file:


Global configurations that change the global behavior.


You can change the query line's prompt, which is QUERY> by default.

    "Prompt": "[peco]"


InitialMatcher has been deprecated. Please use InitialFilter instead.


Specifies the filter name to start peco with. You should specify the name of the filter, such as IgnoreCase, CaseSensitive, SmartCase, Regexp and Fuzzy.


    "StickySelection": true

StickySelection allows selections to persist even between changes to the query. For example, when you set this to true you can select a few lines, type in a new query, select those lines, and then delete the query. The result is all the lines that you selected before and after the modification to the query are left in tact.

Default value for StickySelection is false.


    "OnCancel": "error"

OnCancel is equivalent to --on-cancel command line option.



    "Keymap": {
        "M-v": "peco.ScrollPageUp",
        "C-v": "peco.ScrollPageDown",
        "C-x,C-c": "peco.Cancel"

Key sequences

As of v0.2.0, you can use a list of keys (separated by comma) to register an action that is associated with a key sequence (instead of a single key). Please note that if there is a conflict in the key map, the longest sequence always wins. So In the above example, if you add another sequence, say, C-x,C-c,C-c, then the above peco.Cancel will never be invoked.

Combined actions

As of v0.2.1, you can create custom combined actions. For example, if you find yourself repeatedly needing to select 4 lines out of the list, you may want to define your own action like this:

    "Action": {
        "foo.SelectFour": [
    "Keymap": {
        "M-f": "foo.SelectFour"

This creates a new combined action foo.SelectFour (the format of the name is totally arbitrary, I just like to put namespaces), and assigns that action to M-f. When it's fired, it toggles the range selection mode and highlights 4 lines, and then goes back to waiting for your input.

As a similar example, a common idiom in emacs is that C-c C-c means "take the contents of this buffer and accept it", whatever that means. This adds exactly that keybinding:

    "Action": {
        "selectAllAndFinish": [
    "Keymap": {
        "C-c,C-c": "selectAllAndFinish"

Available keys

Since v0.1.8, in addition to values below, you may put a M- prefix on any key item to use Alt/Option key as a mask.

Name Notes
C-a ... C-z Control + whatever character
C-2 ... C-8 Control + 2..8
C-\\ Note that you need to escape the backslash
F1 ... F12

Key workarounds

Some keys just... don't map correctly / too easily for various reasons. Here, we'll list possible workarounds for key sequences that are often asked for:

You want this Use this instead Notes
Shift+Tab M-[,Z Verified on OS X

Available actions

Name Notes
peco.ForwardChar Move caret forward 1 character
peco.BackwardChar Move caret backward 1 character
peco.ForwardWord Move caret forward 1 word
peco.BackwardWord Move caret backward 1 word
peco.BackToInitialFilter Switch to first filter in the list
peco.BeginningOfLine Move caret to the beginning of line
peco.EndOfLine Move caret to the end of line
peco.EndOfFile Delete one character forward, otherwise exit from peco with failure status
peco.DeleteForwardChar Delete one character forward
peco.DeleteBackwardChar Delete one character backward
peco.DeleteForwardWord Delete one word forward
peco.DeleteBackwardWord Delete one word backward
peco.InvertSelection Inverts the selected lines
peco.KillBeginningOfLine Delete the characters under the cursor backward until the beginning of the line
peco.KillEndOfLine Delete the characters under the cursor until the end of the line
peco.DeleteAll Delete all entered characters
peco.RefreshScreen Redraws the screen. Note that this effectively re-runs your query
peco.SelectPreviousPage (DEPRECATED) Alias to ScrollPageUp
peco.SelectNextPage (DEPRECATED) Alias to ScrollPageDown
peco.ScrollPageDown Moves the selected line cursor for an entire page, downwards
peco.ScrollPageUp Moves the selected line cursor for an entire page, upwards
peco.SelectUp Moves the selected line cursor to one line above
peco.SelectDown Moves the selected line cursor to one line below
peco.SelectPrevious (DEPRECATED) Alias to SelectUp
peco.SelectNext (DEPRECATED) Alias to SelectDown
peco.ScrollLeft Scrolls the screen to the left
peco.ScrollRight Scrolls the screen to the right
peco.ToggleSelection Selects the current line, and saves it
peco.ToggleSelectionAndSelectNext Selects the current line, saves it, and proceeds to the next line
peco.ToggleSingleKeyJump Enables SingleKeyJump mode a.k.a. "hit-a-hint"
peco.SelectNone Remove all saved selections
peco.SelectAll Selects the all line, and save it
peco.SelectVisible Selects the all visible line, and save it
peco.ToggleSelectMode (DEPRECATED) Alias to ToggleRangeMode
peco.CancelSelectMode (DEPRECATED) Alias to CancelRangeMode
peco.ToggleQuery Toggle list between filterd by query and not filterd.
peco.ToggleRangeMode Start selecting by range, or append selecting range to selections
peco.CancelRangeMode Finish selecting by range and cancel range selection
peco.RotateMatcher (DEPRECATED) Use peco.RotateFilter
peco.RotateFilter Rotate between filters (by default, ignore-case/no-ignore-case)
peco.Finish Exits from peco with success status
peco.Cancel Exits from peco with failure status, or cancel select mode

Default Keymap

Note: If in case below keymap seems wrong, check the source code in keymap.go (look for NewKeymap).

Key Action
Esc peco.Cancel
C-c peco.Cancel
Enter peco.Finish
C-f peco.ForwardChar
C-a peco.BeginningOfLine
C-b peco.BackwardChar
C-d peco.DeleteForwardChar
C-e peco.EndOfLine
C-k peco.KillEndOfLine
C-u peco.KillBeginningOfLine
BS peco.DeleteBackwardChar
C-8 peco.DeleteBackwardChar
C-w peco.DeleteBackwardWord
C-g peco.SelectNone
C-n peco.SelectDown
C-p peco.SelectUp
C-r peco.RotateMatcher
C-t peco.ToggleQuery
C-Space peco.ToggleSelectionAndSelectNext
ArrowUp peco.SelectUp
ArrowDown peco.SelectDown
ArrowLeft peco.ScrollPageUp
ArrowRight peco.ScrollPageDown


For now, styles of following 5 items can be customized in config.json.

    "Style": {
        "Basic": ["on_default", "default"],
        "SavedSelection": ["bold", "on_yellow", "white"],
        "Selected": ["underline", "on_cyan", "black"],
        "Query": ["yellow", "bold"],
        "Matched": ["red", "on_blue"]
  • Basic for not selected lines
  • SavedSelection for lines of saved selection
  • Selected for a currently selecting line
  • Query for a query line
  • Matched for a query matched word

Foreground Colors

  • "black" for termbox.ColorBlack
  • "red" for termbox.ColorRed
  • "green" for termbox.ColorGreen
  • "yellow" for termbox.ColorYellow
  • "blue" for termbox.ColorBlue
  • "magenta" for termbox.ColorMagenta
  • "cyan" for termbox.ColorCyan
  • "white" for termbox.ColorWhite

Background Colors

  • "on_black" for termbox.ColorBlack
  • "on_red" for termbox.ColorRed
  • "on_green" for termbox.ColorGreen
  • "on_yellow" for termbox.ColorYellow
  • "on_blue" for termbox.ColorBlue
  • "on_magenta" for termbox.ColorMagenta
  • "on_cyan" for termbox.ColorCyan
  • "on_white" for termbox.ColorWhite


  • "bold" for fg: termbox.AttrBold
  • "underline" for fg: termbox.AttrUnderline
  • "reverse" for fg: termbox.AttrReverse
  • "on_bold" for bg: termbox.AttrBold (this attribute actually makes the background blink on some platforms/environments, e.g. linux console, xterm...)


This is an experimental feature. Please note that some details of this specification may change

By default peco comes with IgnoreCase, CaseSensitive, SmartCase, Regexp and Fuzzy filters, but since v0.1.3, it is possible to create your own custom filter.

The filter will be executed via Command.Run() as an external process, and it will be passed the query values in the command line, and the original unaltered buffer is passed via os.Stdin. Your filter must perform the matching, and print out to os.Stdout matched lines. You filter MAY be called multiple times if the buffer given to peco is big enough. See BufferThreshold below.

Note that currently there is no way for the custom filter to specify where in the line the match occurred, so matched portions in the string WILL NOT BE HIGHLIGHTED.

The filter does not need to be a go program. It can be a perl/ruby/python/bash script, or anything else that is executable.

Once you have a filter, you must specify how the matcher is spawned:

    "CustomFilter": {
        "MyFilter": {
            "Cmd": "/path/to/my-matcher",
            "Args": [ "$QUERY" ],
            "BufferThreshold": 100

Cmd specifies the command name. This must be searcheable via exec.LookPath.

Elements in the Args section are string keys to array of program arguments. The special token $QUERY will be replaced with the unaltered query as the user typed in (i.e. multiple-word queries will be passed as a single string). You may pass in any other arguments in this array. If you omit this in your config, a default value of []string{"$QUERY"} will be used

BufferThreshold specifies that the filter command should be invoked when peco has this many lines to process in the buffer. For example, if you are using peco against a 1000-line input, and your BufferThreshold is 100 (which is the default), then your filter will be invoked 10 times. For obvious reasons, the larger this threshold is, the faster the overall performance will be, but the longer you will have to wait to see the filter results.

You may specify as many filters as you like in the CustomFilter section.



See --layout.


  "SingleKeyJump": {
    "ShowPrefix": true


  "Keymap": {
    "C-e": "peco.ExecuteCommand.Notepad"
  "Command": [
      "Name": "Notepad",
      "Args": ["notepad", "$FILE"],
      "Spawn": true


Does peco work on (msys2|cygwin)?


Non-latin fonts (e.g. Japanese) look weird on my Windows machine...?

Are you using raster fonts?


First, fork this repo, and get your clone locally.

  1. Make sure you have go installed, with GOPATH appropriately set
  2. Make sure you have make installed
  3. Run make installdeps (You only need to do this once, or when you update glide.yml/glide.lock)

To test, run

make test

To build, run

make build

This will create a peco binary in $(RELEASE_DIR)/peco_$(GOOS)_$(GOARCH)/peco$(SUFFIX). Or, of course, you can just run

go build cmd/peco/peco.go

which will create the binary in the local directory.


Test it. In doing so, we may change the repo structure

Implement all(?) of the original percol options


  • Daisuke Maki (lestrrat)
  • mattn
  • syohex


  • HIROSE Masaaki
  • Joel Segerlind
  • Lukas Lueg
  • Mitsuoka Mimura
  • Ryota Arai
  • Shinya Ohyanagi
  • Takashi Kokubun
  • Yuya Takeyama
  • cho45
  • cubicdaiya
  • kei_q
  • negipo
  • sona_tar
  • sugyan
  • swdyh
  • MURAOKA Taro (kaoriya/koron), for aho-corasick search
  • taichi, for the gif working on Windows
  • uobikiemukot
  • Samuel Lemaitre
  • Yousuke Ushiki
  • Linda_pp
  • Tomohiro Nishimura (Sixeight)


Obviously, kudos to the original percol: Much code stolen from

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