lg — Simple universal logger for any command

lg lets you run any command and capture its output and key metadata with zero friction:

lg ls -la
lg curl https://example.org
lg make test

By default, lg writes a single log file into the current directory named:

<command>_<YYYY-MM-DD>_<HH-mm-ss>.log

You can change behavior via a config file at ~/.lg (TOML). See Configuration.

---

Why?

• Zero learning curve: just prefix lg in front of any command.
• Sensible defaults, powerful configuration.
• Timestamps on every line, optional gzip compression, optional split streams.
• Returns the same exit code as the underlying command.

Install

Ubuntu PPA (recommended)

On Ubuntu and derivatives, install from the official PPA:

sudo apt-get update
sudo add-apt-repository ppa:batyan45/stable
sudo apt-get update
sudo apt-get install -y lg

Packages are published for supported Ubuntu releases when available (e.g., LTS like 22.04 Jammy, 24.04 Noble). See the PPA page for build status and supported series: https://launchpad.net/~batyan45/+archive/ubuntu/stable

Build from source

Requirements: Rust (stable) and Cargo.

git clone https://github.com/Batyan45/lg.git
cd lg
cargo build --release
sudo install -Dm755 target/release/lg /usr/local/bin/lg

Build Debian package locally

Requires standard packaging tools:

sudo apt-get update
sudo apt-get install -y build-essential debhelper devscripts dh-cargo rustc cargo
dpkg-buildpackage -us -uc -b
sudo dpkg -i ../lg_1.0.1_amd64.deb  # filename may vary

The package installs /usr/bin/lg and the man page lg(1).

Usage

Basic:

lg <command> [args...]

Examples:

lg echo "hello"
lg python script.py --flag
lg --split-streams --compress gz -- make test

# Keep log lines untouched (no timestamps or [STDOUT]/[STDERR]):
lg --plain-lines -- make test

Exit code passthrough

lg exits with the same code as the wrapped command. This way it can be used in scripts safely.

Configuration

lg will automatically create ~/.lg (TOML) with sensible defaults the first time you run it, so you can tweak it immediately. All keys are optional. Defaults are shown below.

# Where to write logs. If unset, current directory is used.
# output_dir = "/var/log/commands"

# Whether to include arguments into the file name.
# include_args_in_name = false

# If including args, whether to include full argument list (true) or only non-flag positional args (false).
# include_full_args = true

# Replace any characters not safe for file names. Turning this off may cause errors on some filesystems.
# sanitize_filename = true

# File name template. Supported placeholders:
# {cmd}, {args}, {date}, {time}, {ts}, {exit_code}, {hostname}, {cwd}
# filename_template = "{cmd}_{date}_{time}.log"

# Timestamp formatting used for {time} and for per-line timestamps.
# See chrono formatting: https://docs.rs/chrono/latest/chrono/format/strftime/index.html
# time_format = "%H:%M:%S%.3f"
# date_format = "%Y-%m-%d"

# Write timestamp per logged line.
# timestamp_each_line = true

# Write log lines exactly as emitted (no timestamps or stream labels).
# plain_lines = false

# Combine stdout and stderr into a single log file with stream markers.
# If false and split_streams=true, separate .out.log and .err.log are written.
# combine_streams = true

# If true, produce two files: <name>.out.log and <name>.err.log
# split_streams = false

# Also print the wrapped command's output to the terminal (tee behavior).
# tee = true

# Include environment variables in the header. (May expose secrets. Use with care)
# log_env = false

# Gzip compression: one of "none", "gz"
# compress = "none"

# Put exit code into the final file name by adding {exit_code} to the filename_template.
# If {exit_code} is present, the log file is first written to a temporary path and renamed on completion.

Example configuration

See examples/lg.example.toml.

File name templating

Supported placeholders in filename_template:

• {cmd} — base command.
• {args} — arguments string (may be sanitized).
• {date} — current local date formatted by date_format.
• {time} — current local time formatted by time_format.
• {ts} — UNIX epoch seconds.
• {exit_code} — the wrapped command exit code (if available, post-run).
• {hostname} — system hostname.
• {cwd} — current working directory (sanitized).

Man page

A concise lg(1) man page is included; install via the Debian package or see debian/lg.1.

Security considerations

• If log_env = true, be aware environment variables might contain secrets.
• When including arguments in filenames, consider sanitize_filename = true (default).

License

MIT — see LICENSE.