percol

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

• What's this
  • Features
  • Related projects
• Installation
  • PyPI
  • Manual
• Usage
• Example
  • Interactive pgrep / pkill
  • zsh history search
  • tmux
  • Calling percol from Python
• Configuration
  • Customizing prompt
    • Dynamic prompt
    • Custom format specifiers
  • Customizing styles
    • Foreground Colors
    • Background Color
    • Attributes
• Matching Method
  • Migemo support
    • Dictionary settings
    • Minimum query length
  • Pinyin support
  • Switching matching method dynamically
• Tips
  • Selecting multiple candidates
  • Z Shell support

What's this

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 for details.
• Migemo support: By supporting C/Migemo, percol filters Japanese inputs blazingly fast.
  • See matching method for details.

Related projects

• canything by @keiji0
  • A seminal work in interactive grep tools.
• zaw by @nakamuray
  • A zsh-friendly interactive grep tool.
• peco by @lestrrat
  • An interactive grep tool written in Go language.
• fzf by @junegunn
  • 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).

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.

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)

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:

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.

# X / _ / X
percol.view.PROMPT  = ur"<bold><yellow>X / _ / X</yellow></bold> %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.

percol.view.PROMPT = ur"<blue>Input:</blue> %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.

# Change prompt in response to the status of case sensitivity
percol.view.__class__.PROMPT = property(
    lambda self:
    ur"<bold><blue>QUERY </blue>[a]:</bold> %q" if percol.model.finder.case_insensitive
    else ur"<bold><green>QUERY </green>[A]:</bold> %q"
)

Custom format specifiers

# 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.

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", "blac