sel — Select Slices from Text Files

0.2.0 — compact CLI (and Rust library) for extracting fragments from text by line numbers, ranges, positions (line:column), or regex. Streams input so it scales to large files; supports stdin, file output, and colored output with context.

Documentation

Features

• Line selectors: single (42), ranges (10-20), lists (1,5,10-15,22).
• Positional selectors: line:column with per-character context.
• Regex search (-e PATTERN) with optional invert (-v).
• Line context (-c N): N lines around each match, windows merged on overlap.
• Streaming: single-pass BufReader pipeline; memory independent of file size.
• Stdin: no file arg or - reads stdin (positional selectors need a seekable file).
• Output to file (-o PATH), never clobbers unless --force.
• Color (--color auto|always|never) with ANSI highlighting.

Installation

# From crates.io (the crate is published as `sel-rs`; the binary is still `sel`)
cargo install sel-rs

# From source
git clone https://github.com/InkyQuill/sel.git
cd sel && cargo install --path .

Pre-built binaries for Linux, macOS, and Windows are published on the Releases page via cargo-dist.

Claude Code skill (optional)

Teach Claude Code to prefer sel over sed -n '…p' for line extraction:

# User-level
curl -fsSL https://raw.githubusercontent.com/InkyQuill/sel/main/contrib/claude-skill/install.sh | sh

# Project-level (installs into ./.claude/skills/)
curl -fsSL https://raw.githubusercontent.com/InkyQuill/sel/main/contrib/claude-skill/install.sh | sh -s -- --project

See contrib/claude-skill/ for details and uninstall instructions.

Quick examples

# Lines 30–35
sel 30-35 file.txt

# A mix of singles and ranges
sel 1,5,10-15,22 file.txt

# Line 42 with 3 lines of context on each side
sel -c 3 42 file.txt

# Position (line 23, column 260) with 10 chars of context
sel -n 10 23:260 file.txt

# Regex search with context
sel -c 2 -e TODO src/main.rs

# Invert-match: lines that do NOT match
sel -v -e '^\s*#' config.ini

# Multiple files (filename prefix auto-enabled)
sel -e ERROR logs/*.log

# Stdin
cat huge.log | sel -e 'panic!'
sel 10-20 -            # explicit stdin sentinel

# Write to a file, refuse to overwrite
sel 1-100 big.txt -o head.txt
sel 1-100 big.txt -o head.txt --force    # overwrite

# Whole file with line numbers (like `cat -n`)
sel file.txt

Usage (summary)

Run sel --help for the full option list. A detailed reference lives in docs/USAGE.md.

sel [OPTIONS] [SELECTOR_OR_FILE]...
sel [OPTIONS] -e <PATTERN> [FILE]...

Options:
  -c, --context <N>          Lines of context before/after matches
  -n, --char-context <N>     Character context (positions / regex)
  -l, --no-line-numbers      Suppress line numbers
  -e, --regex <PATTERN>      Regular expression pattern
  -v, --invert-match         With -e: emit non-matching lines
  -H, --with-filename        Always print filename prefix
      --color <WHEN>         auto | always | never (default: auto)
  -o, --output <FILE>        Write output to FILE (`-` = stdout)
      --force                With -o, overwrite an existing file
  -h, --help                 Print help
  -V, --version              Print version

Development

Requires Rust 1.92+ (edition 2024), as set in Cargo.toml.

cargo build --release
cargo test
cargo clippy --all-targets -- -D warnings
cargo fmt --check
cargo bench                    # Criterion: benches/large_file.rs

Contributions welcome — see CONTRIBUTING.md and CODE_OF_CONDUCT.md.

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0)
• MIT License (LICENSE-MIT or https://opensource.org/licenses/MIT)

at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual-licensed as above, without any additional terms or conditions.

Author

Pavel Obruchnikov a.k.a InkyQuill — https://github.com/InkyQuill