summary-line

#!/bin/bash
set -euf -o pipefail

##
# Summarize a text file in one line.
#
# This prints a line with the file name and summary like this:
#
#    my.txt: My Notes About Foo Bar
#
# To get the summary, this script finds the first line of the file that
# starts with one or more symbol characters (i.e. non-space, non-alphanum),
# then one or more spaces.
#
# Example shell script:
#
#    #!/bin/foo
#    # Hello
#
# Example markup text:
#
#    !! Hello
#
# The script puts a colon and space after the filename.
#
# Contact: Joel Parker Henderson (joel@joelparkerhenderson.com)
# License: GPL
# Updated: 2015-01-25
##

grep "^[^A-Za-z0-9 ]* " -m 1 -H "$@" | sed 's/:[^ ] */: /'