🔦 flashlog

Highlight log lines that matter — errors, leaked secrets, stack traces — right in the terminal.

journalctl -f | flashlog
cargo build 2>&1 | flashlog
tail -f /var/log/nginx/error.log | flashlog

flashlog reads text from standard input one line at a time. Ordinary lines pass through unchanged; suspicious lines receive a label and terminal highlighting. It is a heuristic filter: it helps surface likely problems and credentials, but it does not interpret or fix the program that produced them.

What it detects

• FATAL — panics, segmentation faults, and core dumps
• SECRET — AWS keys, common sk-…, ghp_… and Slack tokens, bearer credentials, plaintext password fields, and private key headers
• error — common error words, non-zero exit status, and build failures
• trace — common stack trace frames and source file locations

Options

• --only prints only suspicious lines.
• --json emits suspicious lines as JSON objects with kind, line, file, and line_number fields. Ordinary lines are omitted.
• -h or --help prints usage.

For example, to inspect only matching lines from today's journal:

journalctl --since today | flashlog --only

To feed a command's standard output and standard error through flashlog:

cargo build 2>&1 | flashlog

Install

Build the release binary with Rust and Cargo:

cargo install --path .

Or build it locally and put it in a directory on your PATH:

cargo build --release
install -Dm755 target/release/flashlog ~/.local/bin/flashlog

Build from source

git clone https://github.com/horizzon3507/flashlog.git
cd flashlog
cargo build --release
cargo test

flashlog is written in Rust, has no runtime service, and uses one dependency (regex). All filtering happens locally; input is not sent over the network.

Filtering and output controls

• --color auto|always|never controls color. auto colors only terminal output, and NO_COLOR disables it unless --color always is set.
• --levels fatal,secret,error,trace includes only listed categories. --exclude error,trace removes selected categories.
• --context N includes up to N lines before and after each match. Overlapping windows are printed once.
• --summary writes totals and per-category match counts to standard error.
• Pass one or more file paths to inspect them directly. Use - as a file name to read standard input; with no paths, flashlog reads standard input automatically.

File output includes the source path and line number. JSON output contains kind, line, file, and line_number; file is null for standard input. JSON output only includes matching lines, including when --context is used.

flashlog --only --context 2 app.log
flashlog --levels fatal,secret --summary app.log
journalctl -f | flashlog --color never