logger2

A modern, feature-rich replacement for the classic Unix logger(1) CLI — same core job (send a message to syslog), but with truecolor hex output, emoji, JSON output, remote delivery over UDP/TCP, RFC 5424 support, and a fully configurable TOML config file.

Written in Rust. Single static-ish binary, cross-platform, no runtime dependencies.

$ logger2 -l warning "disk usage on /var is at 92%"
2026-07-01 09:41:06.243 ⚠️  WARN [hadi] disk usage on /var is at 92%

Features

• Drop-in familiar CLI — mirrors util-linux logger's flags (-p, -t, -i, -s, -f, -n, -P, -T/-d, -u, -r, -S) so existing scripts and muscle memory transfer directly.
• Truecolor hex output — per-level colors configured as #RRGGBB (or overridden per-invocation with -c), rendered with 24-bit ANSI escapes.
• Emoji decoration — a configurable emoji per severity level, or an ad-hoc override with -e.
• Local and remote syslog — writes to the local syslog Unix socket (/dev/log on Linux, /var/run/syslog on macOS) by default, or to a remote syslog daemon over UDP or TCP with -n/--server.
• RFC 3164 and RFC 5424 framing — pick the legacy BSD format or the modern IETF format with structured data, plus RFC 6587 octet-counting for TCP.
• JSON output mode — --json emits one structured JSON object per line for easy piping into jq, log shippers, or other tooling.
• Structured fields — attach arbitrary key=value pairs with -k, included in both console and JSON output and forwarded as RFC 5424 structured data.
• Fully configurable via TOML — colors, emoji, default priority, output template, network settings, and more, all overridable per-invocation by CLI flags.
• Safe on every platform — local Unix-socket syslog delivery is Linux/macOS/BSD only; on other platforms (e.g. Windows) logger2 degrades gracefully and tells you to use --server for remote delivery instead of panicking or silently failing.
• --dry-run — see exactly what would be printed and sent, without sending anything.

Installation

From crates.io

cargo install logger2

From a release binary

Download the archive for your platform from the Releases page, extract it, and put the logger2 binary on your PATH.

From source

git clone https://github.com/licface/logger2
cd logger2
cargo build --release
# binary at target/release/logger2

Usage

logger2 [OPTIONS] [MESSAGE]...

If MESSAGE is omitted, logger2 reads from --file, then falls back to stdin.

Basic examples

# Simple message at the default priority (user.notice)
logger2 "backup completed successfully"

# Explicit facility.level priority (like the original logger)
logger2 -p local0.error "disk write failed"

# Friendly level name instead of spelling out facility.level
logger2 -l error "disk write failed"

# Custom tag and include the PID
logger2 -t backup-script -i "starting nightly backup"

# Read the message from a file
logger2 -f /var/log/app/last-error.txt -l error

# Pipe a message in
echo "queue depth exceeded threshold" | logger2 -l warning

# One-off color/emoji override, ignoring the config file
logger2 -c "#FF00AA" -e "🚀" -l info "deploy started"

# Ship straight to a remote syslog collector over TCP with RFC 5424 framing
logger2 -n logs.example.com -P 6514 -T -r -l critical "node unreachable"

# Attach structured fields (shown in console output, JSON, and RFC 5424 SD)
logger2 --json -k request_id=abc123 -k user=alice -l info "request handled"

# See what would happen without actually sending or writing anything
logger2 --dry-run -l debug "just checking output"

Levels

trace, debug, info, notice, warning, error, critical, alert, emergency — mapped to standard syslog severities 7 down to 0 (trace is a non-standard convenience level that maps to severity 7, same as debug).

Facilities

All standard syslog facilities are supported: kern, user, mail, daemon, auth, syslog, lpr, news, uucp, cron, authpriv, ftp, ntp, security, console, solaris-cron, and local0–local7.

Configuration file

logger2 looks for a config file in this order (first match wins):

1. --config <path> / LOGGER2_CONFIG environment variable
2. $XDG_CONFIG_HOME/logger2/config.toml (or the platform equivalent, e.g. ~/.config/logger2/config.toml on Linux)
3. ~/.logger2.toml
4. /etc/logger2/config.toml (Unix only)
5. Built-in defaults, if none of the above exist

Generate a starter config with:

logger2 --init-config

Inspect the fully-resolved effective config (defaults + file + no CLI overrides) with:

logger2 --print-config

Example config

[general]
default_priority = "user.notice"
default_tag = ""                          # empty = use the current username
timestamp_format = "%Y-%m-%d %H:%M:%S%.3f"
show_pid = false
max_message_size = 8192

[output]
stderr = true
syslog = true
json = false
template = "{timestamp} {emoji} {level} [{tag}] {message}"

[network]
server = ""                # empty = deliver to the local syslog socket
port = 514
protocol = "udp"           # "udp" or "tcp"
socket = "/dev/log"        # local Unix socket path
rfc5424 = false
octet_count = false
connect_timeout_ms = 2000

[colors]
enabled = true
tag = "#87AFFF"
timestamp = "#808080"
message = "#FFFFFF"

[colors.levels]
trace = "#808080"
debug = "#00AFFF"
info = "#00FF00"
notice = "#00FFFF"
warning = "#FFFF00"
error = "#FF5555"
critical = "#FF00FF"
alert = "#FF0000"
emergency = "#FFFFFF"

[emoji]
enabled = true

[emoji.levels]
trace = "🔍"
debug = "🐛"
info = "ℹ️"
notice = "📝"
warning = "⚠️"
error = "❌"
critical = "🔥"
alert = "🚨"
emergency = "💀"

Command-line flags always take precedence over the config file, which in turn takes precedence over built-in defaults.

Output template placeholders

{timestamp}, {emoji}, {level}, {tag}, {message} are substituted into output.template.

Color and emoji behavior

• Colors are disabled automatically when output is not a TTY, when NO_COLOR is set, or with --no-color. Force them on with --force-color or CLICOLOR_FORCE.
• Emoji can be turned off globally in the config (emoji.enabled = false) or per-invocation with --no-emoji.
• -c/--color and -e/--emoji override the level-based defaults for a single invocation without touching the config file.

Platform notes

• Linux / macOS / BSD: full support, including local syslog delivery over the Unix domain socket.
• Windows: local Unix-socket syslog delivery is not available (there is no /dev/log equivalent); use -n/--server to ship to a remote syslog collector over UDP or TCP, which works everywhere. Console/JSON output works identically on every platform.

Exit codes

Development

make build      # debug build
make test       # run unit + integration tests
make lint       # clippy, warnings as errors
make fmt        # rustfmt
make release    # optimized release build
make cross-all  # cross-compile for all supported targets (needs rustup)
make dist       # cross-compile + package tarballs into dist/

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.

👤 Author

Hadi Cahyadi

Support me on Patreon