Show HN: ch, a terminal tool to highlight specific words in your command output

4 weeks ago 1

A fast, simple terminal tool to highlight specific words in your command output with colors. Perfect for tailing logs, debugging, and making command output more readable.

Automatic color assignment from a preset palette
Custom hex colors for specific words
Case-insensitive matching by default
Whole word extension mode
Fast and efficient - designed for real-time log tailing
Cross-platform - works on macOS and Linux

ch reads from standard input line by line and:

Searches for specified words (case-insensitive by default)
Highlights matches with assigned colors
Handles overlapping matches (first match wins)
Outputs to standard output with ANSI color codes

The tool is optimized for streaming, making it ideal for real-time log monitoring.

ch [options] <word1> <word2> <word3> ...

Highlights specified words with colors from a preset palette.

ch <word1>::<HEXCOLOR> <word2>::<COLORNAME> <word3> ...

Use custom hex colors (with or without # prefix) or named colors. Words without specified colors use preset colors.

Available named colors: red, green, orange, blue, pink, purple

-s - Case-sensitive matching (default is case-insensitive)
-w - Whole word extension - extends match until space or end of line
-b - Use background colors instead of foreground colors

# Only highlights exact case matches echo "Error ERROR error" | ch -s Error

The -w flag extends the match to the entire word (until space or EOL):

# Input: "Notice: backup 13344 - started with name backup_13344.zip" echo "Notice: backup 13344 - started with name backup_13344.zip" | ch -w back # Highlights: "backup" and "backup_13344.zip" (entire words)

The -b flag uses background colors instead of foreground colors:

# Highlight with background colors tail -f app.log | ch -b error warning success # Mix with custom colors tail -f app.log | ch -b error::red warning::orange info::blue

The preset colors use a pastel palette optimized for readability on both light and dark terminals:

Red
Green
Orange
Blue
Pink
Purple

Colors cycle when you have more than 6 words without custom colors.

# Tail a log file with highlighted keywords tail -f app.log | ch error warning success # Highlight with custom colors (hex and named) tail -f app.log | ch error::red warning::orange info::00FF00 # Monitor system logs journalctl -f | ch failed::red error::red success::green started::blue # Watch Docker logs docker logs -f container_name | ch error warning started stopped # Monitor Kubernetes pods kubectl logs -f pod-name | ch error panic fatal warning

# Highlight database queries tail -f query.log | ch SELECT INSERT UPDATE DELETE # Database monitoring mysql -e "SHOW PROCESSLIST;" | ch SELECT UPDATE DELETE INSERT

Development and debugging

# Search and highlight grep -i "error" app.log | ch error exception failed # Highlight build output make 2>&1 | ch error warning success completed # Git log highlighting git log --oneline | ch feat fix docs style refactor # Highlight code patterns cat script.sh | ch function if else error

# Mix preset, named, and hex colors tail -f app.log | ch error::red warning::FF5500 info debug success::green # Case-insensitive by default (highlights: error, Error, ERROR, ErRoR, etc.) tail -f app.log | ch error # Monitor web server logs with named colors tail -f access.log | ch GET::blue POST::orange 404::red 500::red 200::green

# Clone or download the repository git clone <repository-url> cd ch # Initialize Go module go mod init ch # Build go build -o ch # (Optional) Install to your PATH sudo mv ch /usr/local/bin/

ch uses buffered I/O and processes input line by line, making it efficient for: