mpytool 2.3.0

MPY tool - manage files on devices running MicroPython

mpytool

MPY tool - manage files on devices running MicroPython

It is an alternative to the official mpremote.

Features

• Fast file transfers - optimized chunked transfer with automatic compression
• Skip unchanged files - compares size + SHA256 hash, re-upload in <1s
• Auto-detect serial port - no need to specify -p when only one device connected
• Robust REPL handling - works reliably with USB-UART bridges (CP2102, CH340)
• Multiple reset options - soft, MCU, hardware (RTS), bootloader entry
• General-purpose serial terminal - repl and monitor work with any serial device
• Mount local directory - VFS mount (read-only or read-write) for development without uploading to flash, with transparent .mpy compilation and auto-remount after soft reset
• Virtual submounts - ln links files/directories into mounted VFS (PC-side only, no device changes)
• Python API - suitable for IDE integration and automation
• Raw-paste mode - flow-controlled code execution with reduced RAM usage (API)
• Shell completion - ZSH and Bash with remote path completion
• Network support - connect over TCP

See README_mpremote.md for detailed comparison with mpremote.

Installation

pip3 install mpytool

Installation from git (latest development version)

pip3 install git+https://github.com/pavelrevak/mpytool.git

Installation in virtualenv

Create a dedicated virtualenv for CLI tools (keeps your system Python clean):

# Create virtualenv (once)
python3 -m venv ~/.venv/tools

# Install mpytool
~/.venv/tools/bin/pip install mpytool

# Run directly
~/.venv/tools/bin/mpytool --help

To use mpytool command without full path, add the venv bin to end of your PATH:

ZSH (~/.zshrc):

export PATH="$PATH:$HOME/.venv/tools/bin"

Bash (~/.bashrc):

export PATH="$PATH:$HOME/.venv/tools/bin"

Then restart your shell (exec zsh or exec bash) and use mpytool directly.

Adding venv bin at the end of PATH keeps your system python and pip as default, while making mpytool available when not found elsewhere.

Examples

Help

$ mpytool --help

List files

$ mpytool -p /dev/ttyACM0 ls         # list CWD (default)
$ mpytool -p /dev/ttyACM0 ls :/lib   # list /lib

Tree

$ mpytool -p /dev/ttyACM0 tree       # tree of CWD (default)

Copy files (: prefix = device path)

$ mpytool cp main.py :/             # upload file to device root
$ mpytool cp main.py lib.py :/lib/  # upload multiple files to directory
$ mpytool cp myapp :/               # upload directory (creates :/myapp/)
$ mpytool cp myapp :/lib/           # upload directory into :/lib/ (creates :/lib/myapp/)
$ mpytool cp myapp/ :/lib/          # upload directory contents into :/lib/
$ mpytool cp :/main.py ./           # download file to current directory
$ mpytool cp :/ ./backup/           # download entire device to backup/
$ mpytool cp :/old.py :/new.py      # copy file on device
$ mpytool cp -f main.py :/          # force upload even if unchanged
$ mpytool cp -m myapp :/            # compile .py to .mpy via mpy-cross

Path semantics: : = device CWD, :/ = device root. Trailing / on source = copy contents only. Unchanged files are automatically skipped (compares size and SHA256 hash). Use -f or --force to upload all files regardless.

Transfer options

$ mpytool cp -z main.py :/           # force compression (auto-detected by default)
$ mpytool cp --no-compress data.bin :/  # disable compression
$ mpytool -c 8K cp main.py :/        # set chunk size (512, 1K, 2K, 4K, 8K, 16K, 32K)
$ mpytool cp -m myapp :/             # compile .py to .mpy before upload
$ mpytool cp -fm myapp :/            # force upload + compile .mpy

Compression is auto-detected based on device RAM and deflate module availability. Chunk size is auto-detected based on free RAM (larger chunks = faster transfer).

The -m/--mpy flag compiles .py files to .mpy bytecode using mpy-cross before upload. Compiled files are cached in __pycache__/ (recompiled only when source changes). boot.py and main.py are always uploaded as .py (firmware requirement). Requires mpy-cross in PATH (pip install mpy-cross). If mpy-cross version differs from device, automatically uses -b flag to target the correct bytecode version. If mpy-cross is not found, falls back to uploading .py with a warning.

Move/rename on device

$ mpytool mv :/old.py :/new.py      # rename file
$ mpytool mv :/file.py :/lib/       # move file to directory
$ mpytool mv :/a.py :/b.py :/lib/   # move multiple files to directory

View file contents

$ mpytool cat :boot.py            # print file from CWD
$ mpytool cat :/lib/module.py     # print file with absolute path

Make directory, delete files (: prefix = device path)

$ mpytool mkdir :lib :data        # create directories in CWD
$ mpytool mkdir :/lib/subdir      # create with absolute path
$ mpytool rm :old.py              # delete file in CWD
$ mpytool rm :mydir               # delete directory and contents
$ mpytool rm :mydir/              # delete contents only, keep directory
$ mpytool rm :                    # delete everything in CWD
$ mpytool rm :/                   # delete everything on device (root)

Current working directory

$ mpytool pwd                     # print current directory
/
$ mpytool cd :/lib                # change to /lib
$ mpytool cd :subdir              # change to relative path (from CWD)
$ mpytool cd :..                  # change to parent directory
$ mpytool cd :/lib -- ls          # change directory and list files

Module search path (sys.path)

$ mpytool path                    # show current sys.path
'', '/lib'
$ mpytool path : :/lib            # replace entire sys.path
$ mpytool path -f :/custom        # prepend to sys.path (remove duplicates)
$ mpytool path -a :/sdcard/lib    # append to sys.path (remove duplicates)
$ mpytool path -d :/custom        # delete from sys.path
$ mpytool path -f : :/lib :/extra # prepend multiple paths
$ mpytool cd :/app -- path -f :   # combine with cd to set working dir

Path semantics: : = empty string (CWD) in sys.path, :/ = root directory. The -f and -a flags automatically remove duplicates (move existing paths to new position).

Stop, reset and REPL

$ mpytool stop               # stop running program (Ctrl-C)
$ mpytool stop -- repl       # stop and enter REPL
$ mpytool reset              # soft reset (Ctrl-D, runs boot.py/main.py)
$ mpytool reset --raw        # soft reset in raw REPL (clears RAM only)
$ mpytool reset --machine    # MCU reset (machine.reset, auto-reconnect)
$ mpytool reset --machine -t 30  # MCU reset with 30s reconnect timeout
$ mpytool reset --rts        # hardware reset via RTS signal (serial only)
$ mpytool reset --boot       # enter bootloader (machine.bootloader)
$ mpytool reset --dtr-boot   # enter bootloader via DTR/RTS (ESP32 only)
$ mpytool reset -- monitor   # reset and monitor output
$ mpytool repl               # enter REPL mode
$ mpytool sleep 2            # sleep for 2 seconds (useful between commands)

Serial terminal and monitor (general purpose)

$ mpytool repl                       # auto-detect port, 115200 baud
REPL (Ctrl+] to exit)

$ mpytool -v repl                    # verbose: shows CWD and sys.path before REPL
REPL (Ctrl+] to exit)  CWD: /  PATH: : :.frozen :/lib

$ mpytool -p /dev/ttyUSB0 repl       # specify port
$ mpytool -b 9600 repl               # specify baudrate
$ mpytool -p /dev/ttyUSB0 -b 9600 monitor   # monitor at 9600 baud

The repl command with -v flag displays current working directory (CWD) and sys.path before entering REPL, making it easy to see the device state after mount, cd, or path commands.

Both repl and monitor can be used as general-purpose serial tools - not just for MicroPython devices. Use them to interact with any serial device (Arduino, ESP with custom firmware, GPS modules, etc.). When only one serial port is detected, it is used automatically. Default baudrate is 115200.

Execute Python code on device

$ mpytool exec "print('Hello!')"
$ mpytool exec "import sys; print(sys.version)"

Run local Python file on device

$ mpytool run script.py                  # run script (fire-and-forget)
$ mpytool run script.py -- monitor       # run script and capture output

Edit file on device

$ mpytool edit :boot.py              # edit file (uses $VISUAL or $EDITOR)
$ mpytool edit :/lib/config.py       # absolute path
$ mpytool edit --editor vim :main.py # explicit editor
$ mpytool edit :newfile.py           # create new file if doesn't exist

Downloads file to a temp file, opens in editor, uploads back if changed. Editor priority: --editor > $VISUAL > $EDITOR > error.

Device RTC (real-time clock)

$ mpytool rtc                        # display current RTC
2026-02-21 15:30:45

$ mpytool rtc --set                  # set RTC to local PC time
RTC set to 2026-02-21 15:30:45 (local)

$ mpytool rtc --utc                  # set RTC to UTC time
RTC set to 2026-02-21 14:30:45 (UTC)

$ mpytool rtc "2026-02-21 14:30:00"  # set RTC to specific datetime
RTC set to 2026-02-21 14:30:00

Flags: -s/--set and -l/--local both set local time, -u/--utc sets UTC. Manual datetime format: YYYY-MM-DD HH:MM:SS.

Mount local directory on device

$ mpytool mount ./src                       # mount ./src as /remote, auto-start REPL
Mounted ./src on /remote (readonly)
Changed CWD to /remote
REPL (Ctrl+] to exit)

$ mpytool -v mount ./src :/app              # mount as /app instead of /remote (verbose)
Mounted ./src on /app (readonly)
Changed CWD to /app
REPL (Ctrl+] to exit)  CWD: /app  PATH: : :.frozen :/lib

$ mpytool mount -m ./src :/app              # mount with automatic .mpy compilation
Mounted ./src on /app (readonly, .mpy compilation)
Changed CWD to /app
>>> import foo                              # imports /app/foo.mpy (compiled from ./src/foo.py)

$ mpytool mount -w ./workspace :/work       # mount as read-write (can create/modify/delete files)
Mounted ./workspace on /work (read-write)
Changed CWD to /work
>>> f = open('/work/test.txt', 'w'); f.write('hello'); f.close()  # creates local file
>>> import os; os.mkdir('/work/newdir')     # creates local directory

$ mpytool mount ./src -- exec "import main" # mount and run code
$ mpytool mount ./src -- monitor            # mount and monitor output
$ mpytool mount ./app :/app -- mount ./lib :/lib -- repl  # multiple mounts (CWD = /app)
Mounted ./app on /app (readonly)
Changed CWD to /app
Mounted ./lib on /lib (readonly)

Mounts a local directory on the device as a VFS. The device can read, import and execute files from the local directory without uploading them to flash. Changes to local files are immediately visible on the device.

Memory overhead: The VFS agent uses ~4.2KB of RAM on the device (154 lines of MicroPython code injected during mount).

By default, mounts are read-only. Use -w / --writable flag to enable write support — the device can create, modify and delete files in the mounted directory. All changes are written directly to the local filesystem.

-m / --mpy flag: Enables transparent .mpy compilation. When the device imports a module, the .py file is automatically compiled to .mpy bytecode on-demand and served from cache (__pycache__/). Benefits: faster imports, less RAM usage, support for @native/@viper code with -march. Boot files (boot.py, main.py) and empty files remain as .py. If compilation fails, automatically falls back to .py. Prebuilt .mpy files have priority over cache.

The first mount automatically changes CWD to the mount point (mpremote compatibility). Subsequent mounts do not change CWD. Use cd command to change working directory manually if needed. Multiple independent (non-nested) mounts are supported.

After mount, mpytool automatically enters REPL (unless monitor or repl follows). In REPL you can import modules from the mounted directory, Ctrl+D triggers soft reset with automatic re-mount and CWD restoration to the mount point.

Best for: Development, testing, prototyping, debugging. For bulk file transfers (uploading/downloading many files), use cp command instead — it's optimized for throughput.

Security: Paths are validated to prevent traversal outside mount root. Symlinks are followed and checked. Write operations require explicit -w flag.

See Mount VFS Comparison for detailed comparison with mpremote.

Link files into mounted VFS

$ mpytool mount ./app :/ -- ln ./drivers :/lib/ -- repl       # mount app, link drivers into /lib/
$ mpytool mount ./app :/ -- ln ./extra.py :/lib/ -- repl      # link single file into /lib/
$ mpytool mount ./app :/ -- ln ./pkg :/lib/pkg -- repl        # link as specific name
$ mpytool mount ./app :/ -- ln ./pkg/ :/lib/ -- repl          # link package contents into /lib/
$ mpytool mount ./app :/ -- ln ./a.py ./b.py :/lib/ -- repl   # link multiple sources

Links local files or directories into an already mounted VFS as virtual submounts. Works entirely on the PC side — no changes needed on the device. Useful for composing a virtual filesystem from multiple local directories without copying.

Path semantics follow the same trailing / rules as cp: ln dir :/lib/ creates :/lib/dir/..., ln dir/ :/lib/ copies contents into :/lib/.... Destination must be an absolute device path with : prefix.

Serial link speed test

$ mpytool speedtest
SPEEDTEST
               upload      download  verify
     0B             -             -  ok
    16B       11.8K/s       24.4K/s  ok
    32B       13.1K/s       42.6K/s  ok
  ...
  4.00K        120K/s       11.1K/s  ok
  8.00K        157K/s       11.0K/s  ok

Show device information

$ mpytool info
Platform:    rp2
Version:     3.4.0; MicroPython v1.27.0 on 2025-12-09
Impl:        micropython
Machine:     Raspberry Pi Pico with RP2040
Serial:      e660123456789abc
Memory:      36.4 KB / 240 KB (15.15%)
Flash:       120 KB / 1.38 MB (8.52%)

On devices with WiFi or Ethernet, MAC addresses are also shown:

MAC WiFi:    aa:bb:cc:dd:ee:01
MAC WiFi AP: aa:bb:cc:dd:ee:02

Flash operations (RP2 and ESP32)

# RP2 - user flash (entire filesystem area)
$ mpytool flash                       # show flash info and filesystem type
$ mpytool flash read backup.bin       # backup entire user flash
$ mpytool flash write backup.bin      # restore from backup
$ mpytool flash erase                 # quick erase (reset filesystem)
$ mpytool flash erase --full          # full erase

# ESP32 - partitions (by label)
$ mpytool flash                       # list all partitions with filesystem info
Label        Type     Subtype       Address       Size    Block Actual FS     Flags
------------------------------------------------------------------------------------------
factory      app      factory       0x10000      1.94M                        running
nvs          data     nvs            0x9000      24.0K
vfs          data     littlefs     0x200000      2.00M     4 KB littlefs2

Boot partition: factory
Next OTA:       (none)

$ mpytool flash read vfs backup.bin        # backup partition to file
$ mpytool flash write nvs nvs_backup.bin   # restore partition from file
$ mpytool flash erase vfs                  # quick erase partition
$ mpytool flash erase vfs --full           # full erase partition

OTA firmware update (ESP32)

$ mpytool flash ota firmware.app-bin                    # flash to next OTA partition
$ mpytool flash ota firmware.app-bin -- reset --machine          # flash and reboot
$ mpytool flash ota firmware.app-bin -- reset --machine -t 30    # flash and reboot with 30s timeout

Multiple commands separated by --

$ mpytool cp main.py boot.py : -- reset -- monitor
$ mpytool rm :old.py -- cp new.py : -- reset

Auto-detect serial port (if only one device is connected)

$ mpytool ls lib/
          uhttp/
  23.2 KB wlan.py
  4.95 KB wlan_http.py

Tree view

$ mpytool tree
   142 KB ./
  41.3 KB ├─ html/
    587 B │  ├─ index.html
  40.8 KB │  └─ wlan.html
  97.7 KB ├─ lib/
  69.6 KB │  ├─ uhttp/
     93 B │  │  ├─ __init__.py
  26.3 KB │  │  ├─ client.py
  43.2 KB │  │  └─ server.py
  23.2 KB │  ├─ wlan.py
  4.95 KB │  └─ wlan_http.py
     23 B ├─ boot.py
  3.03 KB └─ main.py

Connect over network (TCP, default port 23)

$ mpytool -a 192.168.1.100 ls
$ mpytool -a 192.168.1.100:8266 tree

Set baudrate (default 115200)

$ mpytool -p /dev/ttyACM0 -b 9600 ls

Show version

$ mpytool -V

Python API

>>> import mpytool
>>> conn = mpytool.ConnSerial(port='/dev/ttyACM0', baudrate=115200)
>>> mpy = mpytool.Mpy(conn)
>>> mpy.ls()
[('lib', None), ('boot.py', 215), ('main.py', 3102)]
>>> mpy.get('boot.py')
b'import machine\nimport time\n...'
>>> mpy.put(b'print("Hello")', 'test.py')
>>> mpy.delete('test.py')

Raw-paste mode for efficient code execution (MicroPython 1.17+):

>>> mpy.comm.exec_raw_paste("print('Hello')")  # flow-controlled, less RAM
b'Hello\r\n'

See README_API.md for full API documentation.

Progress and verbose output

Progress is shown by default during file transfers:

$ mpytool cp main.py lib.py :/lib/
[1/2] 100%   1.2KB main.py -> :/lib/main.py
[2/2] 100%   3.4KB lib.py  -> :/lib/lib.py

use -v or --verbose to also show commands being executed:

$ mpytool -v rm /old.py
delete: /old.py

use -q or --quiet to disable all output:

$ mpytool -q cp main.py :/

Output Example

Complete workflow - upload changed files, reset device, and monitor output:

$ mpytool cp ~/Work/mpy/wlan/main.py ~/Work/mpy/wlan/html :/ -- cp ~/Work/mpy/wlan/wlan_http.py ~/Work/mpy/wlan/wlan.py ~/Work/mpy/uhttp/uhttp :/lib/ -- cp ~/Tmp/test0.bin :/lib/ -- reset -- monitor
COPY (chunk: 16K, compress: on)
  [1/9] 100% 3.03K ../mpy/wlan/main.py            -> :/main.py                (compressed)
  [2/9] skip  587B ../mpy/wlan/html/index.html    -> :/html/index.html        (unchanged)
  [3/9] 100% 40.8K ../mpy/wlan/html/wlan.html     -> :/html/wlan.html         (compressed)
  [4/9] skip 4.95K ../mpy/wlan/wlan_http.py       -> :/lib/wlan_http.py       (unchanged)
  [5/9] 100% 23.1K ../mpy/wlan/wlan.py            -> :/lib/wlan.py            (compressed)
  [6/9] skip 43.2K ../mpy/uhttp/uhttp/server.py   -> :/lib/uhttp/server.py    (unchanged)
  [7/9] skip 26.3K ../mpy/uhttp/uhttp/client.py   -> :/lib/uhttp/client.py    (unchanged)
  [8/9] skip   93B ../mpy/uhttp/uhttp/__init__.py -> :/lib/uhttp/__init__.py  (unchanged)
  [9/9] skip 10.0K ../../Tmp/test0.bin            -> :/lib/test0.bin          (unchanged)
  66.9K  29.7K/s  2.3s  speedup 6.5x  (3 transferred, 6 skipped)
RESET
MONITOR (Ctrl+C to stop)

starting web server...
Config file not created
AP started: ESP32 (WPA2_PSK, IP: 192.168.4.1)
Scanning...

Debug output

• -d print warnings (yellow)
• -dd print info messages (purple)
• -ddd print debug messages (blue)

For reporting bugs, please include -ddd output in the issue.

Performance

mpytool uses optimized chunked transfer with automatic compression, which allows copying files very quickly. See README_bench.md for detailed benchmarks.

Summary

• Large files upload: 3x - 5x faster than mpremote
• Small files upload: 2x - 3x faster than mpremote
• Skip unchanged: 1.5x - 2.5x faster than mpremote

Shell Completion

Tab completion for ZSH and Bash with support for commands, options, and remote file paths on the device.

Completion files are in completions/ directory:

• _mpytool - ZSH completion
• mpytool.bash - Bash completion

ZSH

Completion file: completions/_mpytool

Where to put it:

• ~/.zsh/completions/_mpytool (user directory, recommended)
• /usr/local/share/zsh/site-functions/_mpytool (system-wide)

Configuration in ~/.zshrc:

fpath=(~/.zsh/completions $fpath)
autoload -Uz compinit && compinit

Quick install (or update):

mkdir -p ~/.zsh/completions
curl -fsSL https://raw.githubusercontent.com/pavelrevak/mpytool/main/completions/_mpytool -o ~/.zsh/completions/_mpytool
grep -q '\.zsh/completions' ~/.zshrc || echo 'fpath=(~/.zsh/completions $fpath); autoload -Uz compinit && compinit' >> ~/.zshrc
exec zsh

Bash

Completion file: completions/mpytool.bash

Where to put it:

• /etc/bash_completion.d/mpytool (Linux system-wide, requires sudo)
• /usr/local/etc/bash_completion.d/mpytool (macOS Homebrew)
• ~/.mpytool-completion.bash (user directory)

Configuration in ~/.bashrc (only for user directory):

source ~/.mpytool-completion.bash

Quick install (Linux system-wide):

sudo curl -fsSL https://raw.githubusercontent.com/pavelrevak/mpytool/main/completions/mpytool.bash -o /etc/bash_completion.d/mpytool && exec bash

Quick install (macOS Homebrew):

curl -fsSL https://raw.githubusercontent.com/pavelrevak/mpytool/main/completions/mpytool.bash -o /usr/local/etc/bash_completion.d/mpytool && exec bash

Quick install (user directory):

curl -fsSL https://raw.githubusercontent.com/pavelrevak/mpytool/main/completions/mpytool.bash -o ~/.mpytool-completion.bash
grep -q 'mpytool-completion' ~/.bashrc || echo 'source ~/.mpytool-completion.bash' >> ~/.bashrc
exec bash

Completion features

• Tab completion for all commands and aliases
• Remote file/directory completion (cached for 60 seconds)
• Support for -- command separator
• Works with both relative and absolute paths

Requirements

Working only with MicroPython boards, not with CircuitPython

• python v3.10+
• pyserial v3.0+

Running on:

• Linux
• MacOS
• Windows

Windows notes

All commands work on Windows including repl.

CMD.EXE: ANSI colors are disabled, progress indicator works. Log messages use text prefixes (E:, W:, I:, D:).

Git Bash: Full color support (sets TERM environment variable).

Credits

(c) 2022-2026 by Pavel Revak

License

MIT

Support

• Basic support is free over GitHub issues.
• Professional support is available over email: Pavel Revak.