PyLine - Lightweight Terminal Text Editor

PyLine is a minimalist command-line text editor designed for Linux/BSD systems, written in Python 3 with use of systems calls. Originally created in 2018 and modernized in 2025, it combines improved text management with a simple, line-by-line workflow. (Note: This is a hobby project, not a professional application.)

Features

• Theme System: Customizable color schemes with for now only for coloring syntax and listing, adjustable for dark and light themes, basic text and bacground still from terminal theme
• Configuration Management: Persistent settings with JSON-based configuration
• Lightweight & Fast: Runs entirely in terminal with minimal dependencies
• Advanced Hook System: Extensible plugin architecture with support for multiple languages (Python, JavaScript, Perl, Ruby, Lua, PHP, Shell)
• File Operations:
  • Edit existing files with full hook integration
  • Create new files with directory structure creation
  • Truncate existing files
  • Count words, lines and characters with hookable word counting
• Navigation:
  • Move between lines and scroll file with arrow keys
  • Scroll file by keys PageUp and PageDown
  • Jump to end of file (Ctrl+D for EOF)
  • Smart viewport management
• Editing:
  • Line-by-line editing with hook-integrated input handling
  • Preserves existing text when modifying lines
  • Insert/delete line operations with pre/post hooks
  • Comprehensive Undo/Redo system (history limit set to 120)
  • Multi-line text selection with visual indicators
  • Cross-platform clipboard support (X11, Wayland, macOS, Windows)
  • Smart indentation preservation during paste operations
  • Syntax highlighting for Python with advanced token recognition
• File Browser:
  • Colorized directory listings
  • Change working directories with path persistence
  • Make new directories
  • Remove files and directories
  • Rename files and directories
• Hook Management:
  • Visual hook manager interface (hm command)
  • Priority-based hook execution (90 → 10)
  • Runtime enable/disable without restart
  • Support for multiple scripting languages
  • Hook categories: input handlers, event handlers, syntax handlers, editing operations, clipboard operations, session handlers

Example screens

PyLine after the initialization:

Open file option screen:

Example of line selection:

After pasting the selection from clipboard:

Execmode(Filemanager):

Hook manager:

Installation

1st method: Manual run

git clone https://github.com/Peter-L-SVK/PyLine.git
cd PyLine/src/
chmod +x main.py

2nd method (script will run sudo command):

git clone https://github.com/Peter-L-SVK/PyLine.git
cd PyLine/
./install.sh

Configuration

PyLine stores configuration in ~/.pyline/config.json with the following structure:

{
    "paths": {
        "default_path": "/home/<username>",
        "original_path": "/home/<path-to-pyline>/PyLine/src"
    },
    "editor": {
        "theme": "black-on-white"
    },
    "hooks": {
        "enabled": true,
        "auto_reload": false
    },
    "theme": {
        "current": "black-on-white",
        "available_themes": [
            "black-on-white",
            "white-on-black"
        ]
    }
}

Detailed Structure

1. Root Directory (~/.pyline/)

~/.pyline/
├── config.json          # Main JSON configuration
├── themes/              # Color theme definitions
└── hooks/               # Extension hook system

Usage

In case of manual run:

./main.py

If you used install script:

pyline  #works from anywhere

Editor accpets input arguments:

# Edit existing file
./main.py existing_file.txt # pyline existing_file.txt

# Create new file
./main.py new_file.txt  # pyline new_file.txt

The editor will:

1. For existing files:

   • Load the file
   • Enter edit mode immediately

2. For new files:

   • Create new buffer with specified filename
   • Create new directory in file path if doesn't exist already
   • Enter edit mode

3. With no arguments:

   • Show the original interactive menu

4. -i, --info Show program information and exit

5. -h, --help show help message and exit

To unninstall the program:

./install.sh -u

Core Hook System Structure with all possible features and hooks in mind

Advanced Hook System

More about hooks in: hooks-creation and hooks-overview
PyLine features a comprehensive hook system that allows extending functionality through plugins. The hook system supports multiple programming languages and follows a structured directory hierarchy:

~/.pyline/hooks/
├── input_handlers/           # Input processing hooks
│   └── edit_line/           # Line editing handlers
│       ├── smart_tab__90.py  # Priority 90 (high)
│       └── auto_complete.py
├── event_handlers/           # Event-based hooks  
│   ├── pre_save/            # Before saving
│   ├── post_save/           # After saving
│   ├── pre_load/            # Before loading
│   ├── post_load/           # After loading
│   └── on_error/            # Error handling
├── syntax_handlers/         # Syntax processing
│   ├── highlight/           # Syntax highlighting
│   └── lint/               # Code linting
├── editing_ops/            # Editing operations
│   ├── pre_insert/         # Before line insertion
│   ├── post_insert/        # After line insertion  
│   ├── pre_delete/         # Before line deletion
│   └── post_delete/        # After line deletion
├── clipboard_ops/          # Clipboard operations
│   ├── pre_copy/           # Before copying
│   ├── post_copy/          # After copying
│   ├── pre_paste/          # Before pasting
│   └── post_paste/         # After pasting
└── session_handlers/       # Session management
    ├── pre_edit/          # Before editing session
    └── post_edit/         # After editing session

Theme System

Built-in Themes

• black-on-white: Classic black text on white background
• white-on-black: White text on black background (dark mode)

Custom Themes

Create custom themes in ~/.pyline/themes/:

More about themes in: themes-reference

# Create a new theme based on existing one
pyline
# Then type 'tm' for theme manager
# Then 'create my-theme' to create a new theme

Theme file structure (~/.pyline/themes/my-theme.theme):

{
  "name": "My Custom Theme",
  "description": "A custom color scheme",
  "background": "\\033[48;5;COLORm",
  "setterm_background": "color-name",
  "setterm_foreground": "color-name",
  "colors": {
    "reset": "\\033[0m",
    "menu_title": "\\033[1;30m",
    "menu_item": "\\033[34m",
    "line_numbers": "\\033[90m",
    "selection": "\\033[47m\\033[30m",
    "keyword": "\\033[34m",
    "string": "\\033[31m",
    "comment": "\\033[32m",
    "variable": "\\033[33m",
    "number": "\\033[35m",
    "function": "\\033[36m",
    "class": "\\033[1;35m",
    "error": "\\033[1;31m",
    "module": "\\033[1;34m",
    "decorator": "\\033[1;36m",
    "annotation": "\\033[1;33m",
    "directory": "\\033[1;34m",
    "executable": "\\033[1;32m",
    "symlink": "\\033[1;36m",
    "hook_category": "\\033[1;35m",
    "hook_type": "\\033[1;36m",
    "hook_enabled": "\\033[1;32m",
    "hook_disabled": "\\033[1;31m"
  }
}

Editor Menu

Command	Action
1	Edit existing file
2	Create new file
3	Truncate existing or create new file
cls	Clear screen
cw	Count words in the file
hm	Hook manager
hs	Hook status
tm	Theme manager
x	Enter file management mode (exec mode)
i	Info
q	Exit program
Ctrl+D	Escape from function
Ctrl+C	Interupt the program

Hook Management Commands:

• hm - Enter hook manager interface
• ls - List all available hooks
• info - Show detailed hook information
• enable - Enable a specific hook
• disable - Disable a specific hook
• reload - Reload hook system from filesystem

Editor Controls

Command	Action
↑/↓	Navigate between lines / Scroll by lines
PgUp / PgDn	Scroll by 52 lines buffer
Ctrl+B / F	Undo/Redo
Enter/e	Edit current line
i	Insert new line
d	Delete current line or multiple selected
c	Copy current line or multiple selected
v	Paste from clipboard
o	Overwrite lines
s	Start / End of selection
q /esc	Quit editor
w	Write changes
Home	Jump to beginning of the file
Ctrl+D / End	Jump to end of the file

File Management Mode

Command	Action
af	List all files
cwd	Change working directory
cdp	Change the default path
mkdir	Create new directory
rename	Rename a file/directory
rmdir	Remove a non empty/empty directory
rmfile	Remove a file
cls	Clear screen
q	Exit file management
Ctrl+D	Escape from function

Theme Manager Commands

Command	Action
tm	Enter theme manager
ls	List all available themes
use <theme>	Switch to specified theme
info <theme>	Show theme details
create <name>	Create new theme based on current
delete <name>	Delete a theme (cannot delete built-in)
edit <name>	Show theme file location for editing

Requirements

• Hook Language Support:
  • Python: Built-in
  • JavaScript: node runtime
  • Perl: perl interpreter
  • Ruby: ruby interpreter
  • Lua: lua interpreter
  • PHP: php interpreter
  • Shell: bash or zsh interpreter
• Python 3.6+
• Linux(or WSL)/FreeBSD/MacOS system (tested on Fedora 27 MATE, 40/42 Cinnmanon)
• Bash or Zsh shell
• Clipboard: xclip (X11) or wl-clipboard (Wayland) for copy/paste (Comes with GUI/DE)

Known Limitations

• Forground Colors: Only partialy applied for now, when editor colors the syntax of when listing.
• Background Colors: For now not implemeted but counted for in themes and code.

License

GNU GPL v3 - See LICENSE file for details.

Testing

To run all tests:

cd PyLine/tests/
python -m unittest discover

Or run a specific test file:

python -m unittest test_dirops.py

All tests require only Python’s built-in unittest module.

Contributing

Contributions are welcome!
See CONTRIBUTING file for details.

For contact please see my email in profile info or use GitHub’s built-in communication tools.

Please open an issue or pull request for any:

• Bug fixes

• Feature suggestions

• Documentation improvements

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Created by Peter Leukanič in 2018 - A simple editor for when you need to edit text files quickly without leaving the terminal.