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https://github.com/mooz/percol

adds flavor of interactive filtering to the traditional pipe concept of UNIX shell
https://github.com/mooz/percol

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adds flavor of interactive filtering to the traditional pipe concept of UNIX shell

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# percol



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percol adds flavor of interactive selection to the traditional pipe concept on UNIX.



- [What's this](#whats-this)

  - [Features](#features)

  - [Related projects](#related-projects)

- [Installation](#installation)

  - [PyPI](#pypi)

  - [Manual](#manual)

- [Usage](#usage)

- [Example](#example)

    - [Interactive pgrep / pkill](#interactive-pgrep--pkill)

    - [zsh history search](#zsh-history-search)

    - [tmux](#tmux)

    - [Calling percol from Python](#calling-percol-from-python)

- [Configuration](#configuration)

    - [Customizing prompt](#customizing-prompt)

        - [Dynamic prompt](#dynamic-prompt)

        - [Custom format specifiers](#custom-format-specifiers)

    - [Customizing styles](#customizing-styles)

        - [Foreground Colors](#foreground-colors)

        - [Background Color](#background-color)

        - [Attributes](#attributes)

- [Matching Method](#matching-method)

    - [Migemo support](#migemo-support)

        - [Dictionary settings](#dictionary-settings)

        - [Minimum query length](#minimum-query-length)

    - [Pinyin support](#pinyin-support)

    - [Switching matching method dynamically](#switching-matching-method-dynamically)

- [Tips](#tips)

    - [Selecting multiple candidates](#selecting-multiple-candidates)

    - [Z Shell support](#z-shell-support)



## What's this



![optimized](http://mooz.github.io/percol/percol_overview.gif)



percol is an **interactive grep tool** in your terminal. percol



1. receives input lines from `stdin` or a file,

2. lists up the input lines,

3. waits for your input that filter/select the line(s),

4. and finally outputs the selected line(s) to `stdout`.



Since percol just filters the input and output the result to stdout,

it can be used in command-chains with `|` in your shell (**UNIX philosophy!**).



### Features



- **Efficient**: With **lazy loads** of input lines and **query caching**, percol handles huge inputs efficiently.

- **Customizable**: Through configuration file (`rc.py`), percol's behavior including prompts, keymaps, and color schemes can be **heavily customizable**.

  - See [configuration](https://github.com/mooz/percol#configuration) for details.

- **Migemo support**: By supporting [C/Migemo](http://code.google.com/p/cmigemo/), **percol filters Japanese inputs blazingly fast**.

  - See [matching method](https://github.com/mooz/percol#matching-method) for details.



### Related projects



- [canything by @keiji0](https://github.com/keiji0/canything)

  - A seminal work in interactive grep tools.

- [zaw by @nakamuray](https://github.com/zsh-users/zaw)

  - A zsh-friendly interactive grep tool.

- [peco by @lestrrat](https://github.com/lestrrat/peco)

  - An interactive grep tool written in Go language.

- [fzf by @junegunn](https://github.com/junegunn/fzf)

  - An interactive grep tool written in Go language.



## Installation



percol currently supports only Python 2.x.



### PyPI



    $ sudo pip install percol



### Manual



First, clone percol repository and go into the directory.



    $ git clone git://github.com/mooz/percol.git

    $ cd percol



Then, run a command below.



    $ sudo python setup.py install



If you don't have a root permission (or don't wanna install percol with sudo), try next one.



    $ python setup.py install --prefix=~/.local

    $ export PATH=~/.local/bin:$PATH



## Usage



Specifying a filename.



    $ percol /var/log/syslog



Specifying a redirection.



    $ ps aux | percol



## Example



### Interactive pgrep / pkill



Here is an interactive version of pgrep,



    $ ps aux | percol | awk '{ print $2 }'



and here is an interactive version of pkill.



    $ ps aux | percol | awk '{ print $2 }' | xargs kill



For zsh users, command versions are here (`ppkill` accepts options like `-9`).



```sh

function ppgrep() {

    if [[ $1 == "" ]]; then

        PERCOL=percol

    else

        PERCOL="percol --query $1"

    fi

    ps aux | eval $PERCOL | awk '{ print $2 }'

}



function ppkill() {

    if [[ $1 =~ "^-" ]]; then

        QUERY=""            # options only

    else

        QUERY=$1            # with a query

        [[ $# > 0 ]] && shift

    fi

    ppgrep $QUERY | xargs kill $*

}

```



### zsh history search



In your `.zshrc`, put the lines below.



```sh

function exists { which $1 &> /dev/null }



if exists percol; then

    function percol_select_history() {

        local tac

        exists gtac && tac="gtac" || { exists tac && tac="tac" || { tac="tail -r" } }

        BUFFER=$(fc -l -n 1 | eval $tac | percol --query "$LBUFFER")

        CURSOR=$#BUFFER         # move cursor

        zle -R -c               # refresh

    }



    zle -N percol_select_history

    bindkey '^R' percol_select_history

fi

```



Then, you can display and search your zsh histories incrementally by pressing `Ctrl + r` key.



### tmux



Here are some examples of tmux and percol integration.



    bind b split-window "tmux lsw | percol --initial-index $(tmux lsw | awk '/active.$/ {print NR-1}') | cut -d':' -f 1 | tr -d '\n' | xargs -0 tmux select-window -t"

    bind B split-window "tmux ls | percol --initial-index $(tmux ls | awk \"/^$(tmux display-message -p '#{session_name}'):/ {print NR-1}\") | cut -d':' -f 1 | tr -d '\n' | xargs -0 tmux switch-client -t"



By putting above 2 settings into `tmux.conf`, you can select a tmux window with `${TMUX_PREFIX} b` keys and session with `${TMUX_PREFIX} B` keys.



Attaching to running tmux sessions can also be made easier with percol with this function(tested to work in bash and zsh)



```sh

function pattach() {

    if [[ $1 == "" ]]; then

        PERCOL=percol

    else

        PERCOL="percol --query $1"

    fi



    sessions=$(tmux ls)

    [ $? -ne 0 ] && return



    session=$(echo $sessions | eval $PERCOL | cut -d : -f 1)

    if [[ -n "$session" ]]; then

        tmux att -t $session

    fi

}

```



### Calling percol from Python



Even though Percol is mainly designed as a UNIX command line tool, you can call it from your Python code like so:



```python

from cStringIO import StringIO

from percol import Percol

from percol.actions import no_output



def main(candidates):

    si, so, se = StringIO(), StringIO(), StringIO()

    with Percol(

            actions=[no_output],

            descriptors={'stdin': si, 'stdout': so, 'stderr': se},

            candidates=iter(candidates)) as p:

        p.loop()

    results = p.model_candidate.get_selected_results_with_index()

    return [r[0] for r in results]



if __name__ == "__main__":

    candidates = ['foo', 'bar', 'baz']

    results = main(candidates)

    print("You picked: {!r}".format(results))

```



## Configuration



Configuration file for percol should be placed under `${HOME}/.percol.d/` and named `rc.py`.



Here is an example `~/.percol.d/rc.py`.



```python

# X / _ / X

percol.view.PROMPT  = ur"X / _ / X %q"



# Emacs like

percol.import_keymap({

    "C-h" : lambda percol: percol.command.delete_backward_char(),

    "C-d" : lambda percol: percol.command.delete_forward_char(),

    "C-k" : lambda percol: percol.command.kill_end_of_line(),

    "C-y" : lambda percol: percol.command.yank(),

    "C-t" : lambda percol: percol.command.transpose_chars(),

    "C-a" : lambda percol: percol.command.beginning_of_line(),

    "C-e" : lambda percol: percol.command.end_of_line(),

    "C-b" : lambda percol: percol.command.backward_char(),

    "C-f" : lambda percol: percol.command.forward_char(),

    "M-f" : lambda percol: percol.command.forward_word(),

    "M-b" : lambda percol: percol.command.backward_word(),

    "M-d" : lambda percol: percol.command.delete_forward_word(),

    "M-h" : lambda percol: percol.command.delete_backward_word(),

    "C-n" : lambda percol: percol.command.select_next(),

    "C-p" : lambda percol: percol.command.select_previous(),

    "C-v" : lambda percol: percol.command.select_next_page(),

    "M-v" : lambda percol: percol.command.select_previous_page(),

    "M-<" : lambda percol: percol.command.select_top(),

    "M->" : lambda percol: percol.command.select_bottom(),

    "C-m" : lambda percol: percol.finish(),

    "C-j" : lambda percol: percol.finish(),

    "C-g" : lambda percol: percol.cancel(),

})

```



### Customizing prompt



In percol, a prompt consists of two part: _PROMPT_ and _RPROMPT_, like zsh. As the following example shows, each part appearance can be customized by specifying a prompt format into `percol.view.PROMPT` and `percol.view.RPROMPT` respectively.



```python

percol.view.PROMPT = ur"Input: %q"

percol.view.RPROMPT = ur"(%F) [%i/%I]"

```



In prompt formats, a character preceded by `%` indicates a _prompt format specifier_ and is expanded into a corresponding system value.



- `%%`

    - Display `%` itself

- `%q`

    - Display query and caret

- `%Q`

    - Display query without caret

- `%n`

    - Page number

- `%N`

    - Total page number

- `%i`

    - Current line number

- `%I`

    - Total line number

- `%c`

    - Caret position

- `%k`

    - Last input key



#### Dynamic prompt



By changing percol.view.PROMPT into a getter, percol prompts becomes more fancy.



```python

# Change prompt in response to the status of case sensitivity

percol.view.__class__.PROMPT = property(

    lambda self:

    ur"QUERY [a]: %q" if percol.model.finder.case_insensitive

    else ur"QUERY [A]: %q"

)

```



#### Custom format specifiers



```python

# Display finder name in RPROMPT

percol.view.prompt_replacees["F"] = lambda self, **args: self.model.finder.get_name()

percol.view.RPROMPT = ur"(%F) [%i/%I]"

```



### Customizing styles



For now, styles of following 4 items can be customized in `rc.py`.



```python

percol.view.CANDIDATES_LINE_BASIC    = ("on_default", "default")

percol.view.CANDIDATES_LINE_SELECTED = ("underline", "on_yellow", "white")

percol.view.CANDIDATES_LINE_MARKED   = ("bold", "on_cyan", "black")

percol.view.CANDIDATES_LINE_QUERY    = ("yellow", "bold")

```



Each RHS is a tuple of style specifiers listed below.



#### Foreground Colors



- `"black"`   for `curses.COLOR_BLACK`

- `"red"`     for `curses.COLOR_RED`

- `"green"`   for `curses.COLOR_GREEN`

- `"yellow"`  for `curses.COLOR_YELLOW`

- `"blue"`    for `curses.COLOR_BLUE`

- `"magenta"` for `curses.COLOR_MAGENTA`

- `"cyan"`    for `curses.COLOR_CYAN`

- `"white"`   for `curses.COLOR_WHITE`



#### Background Color



- `"on_black"`   for `curses.COLOR_BLACK`

- `"on_red"`     for `curses.COLOR_RED`

- `"on_green"`   for `curses.COLOR_GREEN`

- `"on_yellow"`  for `curses.COLOR_YELLOW`

- `"on_blue"`    for `curses.COLOR_BLUE`

- `"on_magenta"` for `curses.COLOR_MAGENTA`

- `"on_cyan"`    for `curses.COLOR_CYAN`

- `"on_white"`   for `curses.COLOR_WHITE`



#### Attributes



- `"altcharset"` for `curses.A_ALTCHARSET`

- `"blink"`      for `curses.A_BLINK`

- `"bold"`       for `curses.A_BOLD`

- `"dim"`        for `curses.A_DIM`

- `"normal"`     for `curses.A_NORMAL`

- `"standout"`   for `curses.A_STANDOUT`

- `"underline"`  for `curses.A_UNDERLINE`

- `"reverse"`    for `curses.A_REVERSE`



## Matching Method



By default, percol interprets input queries by users as **string**. If you prefer **regular expression**, try `--match-method` command line option.



    $ percol --match-method regex



### Migemo support



percol supports **migemo** (http://0xcc.net/migemo/) matching, which allows us to search Japanese documents with ASCII characters.



    $ percol --match-method migemo



To use this feature, you need to install C/Migemo (https://github.com/koron/cmigemo). In Ubuntu, it's simple:



    $ sudo apt-get install cmigemo



After that, by specifying a command line argument `--match-method migemo`, you can use migemo in percol.



NOTE: This feature uses `python-cmigemo` package (https://github.com/mooz/python-cmigemo). Doing `pip install percol` also installs this package too.



#### Dictionary settings



By default, percol assumes the path of a dictionary for migemo is `/usr/local/share/migemo/utf-8/migemo-dict`. If the dictionary is located in a different place, you should tell the location via `rc.py`.



For example, if the path of the dictionary is `/path/to/a/migemo-dict`, put lines below into your `rc.py`.



```python

from percol.finder import FinderMultiQueryMigemo

FinderMultiQueryMigemo.dictionary_path = "/path/to/a/migemo-dict"

```



#### Minimum query length



If the query length is **too short**, migemo generates **very long** regular expression. To deal with this problem, percol does not pass a query if the length of the query is shorter than **2** and treat the query as raw regular expression.



To change this behavior, change the value of `FinderMultiQueryMigemo.minimum_query_length` like following settings.



```python

from percol.finder import FinderMultiQueryMigemo

FinderMultiQueryMigemo.minimum_query_length = 1

```



### Pinyin support



Now percol supports **pinyin** (http://en.wikipedia.org/wiki/Pinyin) for matching Chinese characters.



    $ percol --match-method pinyin



In this matching method, first char of each Chinese character's pinyin sequence is used for matching.

For example, 'zw' matches '中文' (ZhongWen), '中午'(ZhongWu), '作为' (ZuoWei) etc.



Extra package pinin(https://pypi.python.org/pypi/pinyin/0.2.5) needed.



### Switching matching method dynamically



Matching method can be switched dynamically (at run time) by executing `percol.command.specify_finder(FinderClass)` or `percol.command.toggle_finder(FinderClass)`. In addition, `percol.command.specify_case_sensitive(case_sensitive)` and `percol.command.toggle_case_sensitive()` change the matching status of case sensitivity.



```python

from percol.finder import FinderMultiQueryMigemo, FinderMultiQueryRegex

percol.import_keymap({

    "M-c" : lambda percol: percol.command.toggle_case_sensitive(),

    "M-m" : lambda percol: percol.command.toggle_finder(FinderMultiQueryMigemo),

    "M-r" : lambda percol: percol.command.toggle_finder(FinderMultiQueryRegex)

})

```



## Tips



### Selecting multiple candidates



You can select and let percol to output multiple candidates by `percol.command.toggle_mark_and_next()` (which is bound to `C-SPC` by default).



`percol.command.mark_all()`, `percol.command.unmark_all()` and `percol.command.toggle_mark_all()` are useful to mark / unmark all candidates at once.



## Z Shell support



A zsh completing-function for percol is available in https://github.com/mooz/percol/blob/master/tools/zsh/_percol .