hl

A tiny, zero-dependency text highlighter for your terminal.

Pipe anything into hl and color-highlight words, tokens, or regex patterns with ANSI colors - great for tail -f logs, grepping, and general terminal life.

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Preview

Features

• Literal or regex matching - plain words by default, or wrap a pattern in /.../ for sed BRE regex
• Multiple patterns per call, applied left to right (up to 12)
• Overlapping matches nest - when one pattern highlights inside another, the outer color is restored afterwards instead of being cleared
• 14 colors, including bright variants with short aliases (bred, bgreen, ...)
• Zero dependencies - pure Bash + sed + awk + tput/ANSI, nothing to install
• Streaming - output appears line by line, so tail -f | hl and other live pipelines work as you would expect
• Pipe-friendly - reads stdin, writes stdout, plays nicely with tail, grep, journalctl, CI logs, anything text-based

Requirements

• bash (4.0+)
• sed
• awk (any POSIX awk - mawk, gawk, and BSD awk all work)
• tput (optional - falls back to raw ANSI escape codes if unavailable)

No package manager, no runtime, no build step.

macOS note: hl works with the system BSD sed, but a few regex constructs (\|, \+, \?) are GNU extensions and will not match under it. See Regex support. brew install gnu-sed and putting gnubin on your PATH gets you the full set.

Installation

Quick install (curl):

sudo curl -fsSL https://raw.githubusercontent.com/bytebeast/hl/main/hl -o /usr/local/bin/hl
sudo chmod +x /usr/local/bin/hl

Clone and link:

git clone https://github.com/bytebeast/hl.git
cd hl
chmod +x hl
ln -s "$(pwd)/hl" /usr/local/bin/hl   # or anywhere on your $PATH

Verify it's on your PATH:

hl <<< "installed correctly"

Usage

echo "text" | hl pattern:color [pattern:color ...]
hl -h | --help

• Literal match (default): hl word:red
• Regex match (wrap the pattern in /.../, sed BRE syntax): hl '/H[0-9]/':blue

The color is taken from the last colon in the argument, so patterns may contain colons themselves (hl 'level:error:bred' highlights level:error).

Bad input is a hard error: an unknown color, a missing colon, or more than 12 patterns exits with status 2 and a message on stderr.

Examples

# Highlight a single word
echo "The car is an H1 model" | hl car:red

# Highlight using a regex
echo "The car is an H1 model" | hl '/H[0-9]/':blue

# Stack multiple patterns
echo "The car is an H1 model" | hl car:red model:green '/H[0-9]/':blue

# Tail a log and flag errors/warnings in bright colors
tail -f app.log | hl ERROR:bred WARN:byellow INFO:cyan

# Alternation (GNU sed)
journalctl -f | hl '/error\|fatal\|panic/':bred

# Timestamps - note the colons inside the pattern
hl '/[0-9]\{2\}:[0-9]\{2\}:[0-9]\{2\}/':bcyan < app.log

# IP addresses
hl '/[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}/':bmagenta < access.log

# Works with anything piped over stdout
grep -i "timeout" server.log | hl timeout:bred

Colors

Name	Alias	Name	Alias
black		bright_red	bred
red		bright_green	bgreen
green		bright_yellow	byellow
yellow		bright_blue	bblue
blue		bright_magenta	bmagenta
magenta		bright_cyan	bcyan
cyan
white

Regex support

Regex mode uses sed BRE syntax, not PCRE. The portable subset works everywhere; the GNU column is what you get from GNU sed on Linux, and what macOS's BSD sed will silently fail to match.

Construct	Meaning	Availability
.	Any character	POSIX
*	Zero or more	POSIX
[abc] [^abc] [[:digit:]]	Bracket expressions	POSIX
^ $	Anchors	POSIX
\(...\)	Group	POSIX
\1 ... \9	Backreference	POSIX
\{n\} \{n,\} \{n,m\}	Intervals	POSIX
|	Alternation	GNU only
\+ \?	One-or-more, zero-or-one	GNU only
\w \s \b	Shorthand classes	GNU only

There is no \d. Use [0-9] or [[:digit:]].

Note that +, ?, {, }, (, ) and | are literal characters in BRE - you escape them to make them special, which is the opposite of PCRE.

Notes

• Literal mode escapes every BRE metacharacter (\ . * [ ^ $), so hl 'a.b:red' matches the three-character string a.b and not axb.
• Overlapping patterns nest properly. Later patterns can highlight inside text an earlier pattern already colored, and the enclosing color resumes when the inner match ends.
• Colors gracefully degrade: if tput isn't available, hl falls back to raw ANSI escape sequences.
• hl with no arguments passes stdin straight through.

Limitations

• /.../ is ambiguous with paths. hl '/usr/:red' is read as the regex usr, not the literal string /usr/. To match the slashes, stay in regex mode and bracket them: hl '/[/]usr[/]/':red.
• A $ anchor may miss if an earlier pattern already highlighted the end of the line.
• . and negated classes like [^x] can match the internal marker bytes hl uses to track highlights, which can produce odd output when combined with earlier patterns.
• Maximum 12 pattern:color pairs per invocation.

Contributing

Issues and pull requests are welcome. If you're proposing a larger change, please open an issue first to discuss what you'd like to change.

License

Released under the MIT License.

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If hl saved you some grep -A -B gymnastics or made your logs easier to read, please consider giving it a ⭐ star - it helps other people find the project and keeps it maintained.