lf

README

LF

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This is a work in progress. Use at your own risk.

lf (as in "list files") is a terminal file manager written in Go. It is heavily inspired by ranger with some missing and extra features. Some of the missing features are deliberately omitted since it is better if they are handled by external tools.

Features

• Cross-platform (Linux, OSX, BSDs, Windows (partial))
• Single binary without any runtime dependencies (except for terminfo database)
• Fast startup and low memory footprint (due to native code and static binaries)
• Server/client architecture to share file selection between multiple instances
• Custom commands as shell commands
• Sync (waiting and non-waiting) and async commands
• Fully customizable keybindings
• Preview filtering (for source highlight, archives, pdfs/images as text etc.)

Non-Features

• Tabs or windows (handled by the window manager or the terminal multiplexer)
• Built-in pager (handled by your pager of choice)
• Image previews (cool but no standard available)

May-Futures

• Bookmarks
• Colorschemes

Installation

See releases for pre-built binaries.

If you like to build from the source:

go get -u github.com/gokcehan/lf

See packages for community maintained packages.

Usage

After the installation lf command should start the application in the current directory.

Run lf -help to see command line options.

Run lf -doc to see the documentation.

See etc directory to integrate lf to your shell or editor. An example configuration file can also be found in this directory.

Documentation

Overview

lf is a terminal file manager.

Source code can be found in the repository at https://github.com/gokcehan/lf.

This documentation can either be read from terminal using "lf -doc" or online at https://godoc.org/github.com/gokcehan/lf.

Reference

The following commands are provided by lf with default keybindings:

up                (default "k" and "<up>")
half-up           (default "<c-u>")
page-up           (default "<c-b>")
down              (default "j" and "<down>")
half-down         (default "<c-d>")
page-down         (default "<c-f>")
updir             (default "h" and "<left>")
open              (default "l" and "<right>")
quit              (default "q")
bot               (default "G")
top               (default "gg")
read              (default ":")
read-shell        (default "$")
read-shell-wait   (default "!")
read-shell-async  (default "&")
search            (default "/")
search-back       (default "?")
search-next       (default "n")
search-prev       (default "N")
toggle            (default "<space>")
invert            (default "v")
yank              (default "y")
clear             (default "c")
delete            (default "d")
put               (default "p")
renew             (default "<c-l>")

The following commands are provided by lf without default keybindings:

sync  synchronizes yanked/deleted files with server
echo  prints its arguments to the message line
cd    changes working directory to its argument
push  simulate key pushes given in its argument

The following options can be used to customize the behavior of lf:

dirfirst   bool    (default on)
hidden     bool    (default off)
preview    bool    (default on)
reverse    bool    (default off)
scrolloff  int     (default 0)
tabstop    int     (default 8)
filesep    string  (default ":")
ifs        string  (default "") (not exported if empty)
previewer  string  (default "") (not filtered if empty)
shell      string  (default "/bin/sh")
showinfo   string  (default "none")
sortby     string  (default "natural")
timefmt    string  (default "Mon Jan _2 15:04:05 2006")
ratios     string  (default "1:2:3")

The following variables are exported for shell commands:

$f   current file
$fs  marked file(s) separated with ':'
$fx  current file or marked file(s) if any

Configuration

The configuration file should be located at:

$XDG_CONFIG_HOME/lf/lfrc"

If "$XDG_CONFIG_HOME" is not set, it defaults to "$HOME/.config" so the location should be:

~/.config/lf/lfrc

A sample configuration file can be found at https://github.com/gokcehan/lf/blob/master/etc/lfrc.example.

Prefixes

The following command prefixes are used by lf:

:  read (default)    built-in command
$  read-shell        shell command
!  read-shell-wait   shell command waiting for key press
&  read-shell-async  asynchronous shell command
/  search            search file in current directory
?  search-back       search file in the reverse order

The same evaluator is used for the command line and the configuration file. The difference is that prefixes are not necessary in the command line. Instead different modes are provided to read corresponding commands. Note that by default these modes are mapped to the prefix keys above.

Syntax

Characters from "#" to "\n" are comments and ignored:

# comments start with '#'

There are three special commands for configuration.

"set" is used to set an option which could be boolean, integer, or string:

set hidden        # boolean on
set nohidden      # boolean off
set hidden!       # boolean toggle
set scrolloff 10  # integer value
set sortby time   # string value w/o quotes

"map" is used to bind a key to a command which could be built-in command, custom command, or shell command:

map gh cd ~       # built-in command
map D trash       # custom command
map i $less "$f"  # shell command
map u !du -h .    # waiting shell command

You can delete an existing binding by leaving the expression empty:

map gh            # deletes 'gh' mapping

"cmd" is used to define a custom command

cmd usage $du -h . | less

You can delete an existing command by leaving the expression empty:

cmd trash         # deletes trash command

If there is no prefix then ":" is assumed:

map zt set showinfo time

An explicit ":" could be provided to group statements until a "\n" occurs which is especially useful for "map" and "cmd" commands:

map st :set sortby time; set showinfo time

If you need multiline you can wrap statements in "{{" and "}}" after the proper prefix.

map st :{{
	set sortby time
	set showinfo time
}}

Mappings

The usual way to map a key sequence is to assign it to a named or unnamed command. While this provides a clean way to remap builtin keys as well as other commands, it can be limiting at times. For this reason "push" command is provided by lf. This command is used to simulate key pushes given as its arguments. You can "map" a key to a "push" command with an argument to create various keybindings.

This is mainly useful for two purposes. First, it can be used to map a command with a command count:

map <c-j> push 10j

Second, it can be used to avoid typing the name when a command takes arguments:

map r push :rename<space>

One thing to be careful is that since "push" command works with keys instead of commands it is possible to accidentally create recursive bindings:

map j push 2j

These types of bindings create a deadlock when executed.

Commands

For demonstration let us write a shell command to move selected file(s) to trash.

A first attempt to write such a command may look like this:

cmd trash ${{
	mkdir -p ~/.trash
	if [ -z $fs ]; then
		mv --backup=numbered "$f" $HOME/.trash
	else
		IFS=':'; mv --backup=numbered $fs $HOME/.trash
	fi
}}

We check "$fs" to see if there are any marked files. Otherwise we just delete the current file. Since this is such a common pattern, a separate "$fx" variable is provided. We can use this variable to get rid of the conditional:

cmd trash ${{
	mkdir -p ~/.trash
	IFS=':'; mv --backup=numbered $fx $HOME/.trash
}}

The trash directory is checked each time the command is executed. We can move it outside of the command so it would only run once at startup:

${{ mkdir -p ~/.trash }}

cmd trash ${{ IFS=':'; mv --backup=numbered $fx $HOME/.trash }}

Since these are one liners, we can drop "{{" and "}}":

$mkdir -p ~/.trash

cmd trash $IFS=':'; mv --backup=numbered $fx $HOME/.trash

Finally note that we set "IFS" variable accordingly in the command. Instead we could use the "ifs" option to set it for all commands (e.g. "set ifs ':'"). This could be especially useful for interactive use (e.g. "rm $fs" would simply work). This option is not set by default as things may behave unexpectedly at other places.

File Operations

lf uses the underlying "cp" and "mv" shell commands for file operations. For this purpose, when you "yank" (i.e. copy) a file, it doesn't actually copy the file on the disk, but only records its name to memory. The actual file operation takes place when you do the "put" in which case the "cp" command is used. Similarly the "mv" command is used for "delete" (i.e. cut or kill) followed by "put". These traditional names (e.g. "yank", "delete", and "put") are picked instead of the other common convention (e.g. copy and cut) to resemble the default keybinds for these operations.

Opening Files

You can use "open-file" command to open a file. This is a special command called by "open" when the current file is not a directory. Normally a user maps the "open" command to a key (default "l") and customize "open-file" command as desired. You can define it just as you would define any other command:

cmd open-file $IFS=':'; vim $fx

It is possible to use different command types:

cmd open-file &xdg-open "$f"

You may want to use either file extensions or mime types from "file" command:

cmd open-file ${{
	case $(file --mime-type "$f" -b) in
		text/*) IFS=':'; vim $fx;;
		*) IFS=':'; for f in $fx; do xdg-open "$f" > /dev/null 2> /dev/null & done;;
	esac
}}

lf does not come bundled with a file opener. You can use any of the existing file openers as you like. Possible options are "open" (for Mac OS X only), "xdg-utils" (executable name is "xdg-open"), "libfile-mimeinfo-perl" (executable name is "mimeopen"), "rifle" (ranger's default file opener), or "mimeo" to name a few.

Previewing Files

lf previews files on the preview pane by printing the file until the end or the preview pane is filled. This output can be enhanced by providing a custom preview script for filtering. This can be used to highlight source codes, list contents of archive files or view pdf or image files as text to name few. For coloring lf recognizes ansi escape codes.

In order to use this feature you need to set the value of "previewer" option to the path of an executable file. lf passes the current file name as the first argument and the height of the preview pane as the second argument when running this file. Output of the execution is printed in the preview pane. You may want to use the same script in your pager mapping as well if any:

set previewer ~/.config/lf/pv.sh
map i $~/.config/lf/pv.sh "$f" | less -R

Since this script is called for each file selection change it needs to be as efficient as possible and this responsibility is left to the user. You may use file extensions to determine the type of file more efficiently compared to obtaining mime types from "file" command. Extensions can then be used to match cleanly within a conditional:

#!/bin/sh

case "$1" in
	*.tar*) tar tf "$1";;
	*.zip) unzip -l "$1";;
	*.rar) unrar l "$1";;
	*.7z) 7z l "$1";;
	*.pdf) pdftotext "$1" -;;
	*) highlight -O ansi "$1" || cat "$1";;
esac

Another important consideration for efficiency is the use of programs with short startup times for preview. For this reason, "highlight" is recommended over "pygmentize" for syntax highlighting. Besides, it is also important that the application is processing the file on the fly rather than first reading it to the memory and then do the processing afterwards. This is especially relevant for big files. lf automatically closes the previewer script output pipe with a SIGPIPE when enough lines are read. When everything else fails, you can make use of the height argument to only feed the first portion of the file to a program for preview.