svgbob_live.sh - live preview of ASCII diagrams as SVG using svgbob

svgbob_live.sh

#!/usr/bin/env bash

### svgbob live preview ###

# DESCRIPTION
#   Runs svgbob_cli whenever a file is changed (specified at launch)
#   and open it with eog (eye of gnome)
# AUTHOR
#   Leigh Oliver, 18/12/2022
# USAGE
#   svgbob_live <filename>
# REQUIREMENTS
#   inotify-tools (apt package)
#   svgbob_cli (cargo crate)

# check required commands are installed
if ! command -v svgbob_cli &> /dev/null
then
    echo "svgbob_cli could not be found"
    echo "try: cargo install svgbob_cli"
    exit 1
fi

if ! command -v inotifywait &> /dev/null
then
    echo "inotifywait could not be found"
    echo "try: apt install inotify-tools"
    exit 1
fi

# store input filename
inputfile="${1}"
# create a temporary output file for svgbob_live
outputfile="$(mktemp).svg"

# run svgbob once, and open eog
svgbob_cli "$inputfile" > "$outputfile"
eog -gn "$outputfile" &

# store the PID of eog, so we can exit the loop below if it's closed
eogpid="$!"

# while eog is running
while ps -p "$eogpid" > /dev/null
do
  # when file changes, re-run svgbob command. 
  # eog will then automagically refresh with the new changes!
  # timeout of 1 second, preventing crazy loop speeds
  inotifywait -qq -e close_write "$inputfile" -t 1
  result="$?"
  if [ "$result" != "2" ];
  then
      svgbob_cli "$inputfile" > "$outputfile"
  fi
done

exit 0