## Here is an example for Autoconf.

syntax autoconf "\.(ac|m4)$"
comment "#"

# Keywords:
color yellow "\<(if|test|then|elif|else|fi|for|in|do|done)\>"
color yellow "(=|!=|&&|\|\|)"

# Macros:
color cyan "\<[[:upper:]_[:digit:]]+\>"

# Version numbers:
color red "\<[-_.0-9]+\>"

# Strings:
color red "\"[^"]*\""  "\'[^']*\'"

# Backticks:
color green "`[^`]*`"

# Error lines:
color brightred "^\*\*\*.*"

# Brackets:
color magenta "\[|\]|\(|\)"

# Comments:
color blue "^[[:blank:]]*#.*"  "\<dnl.*"

# Trailing whitespace:
color ,green "[[:space:]]+$"