A reasonable approximation of ghcid for arbitrary files and interpreters, with nice scrolling and searching via less. Only needs inotifywait on the $PATH.

watchfile

#! /usr/bin/env sh

# Example usage:
# $ watchfile Test.idr idris2 --check
# $ watchfile test.sh shellcheck


file=$1; shift
tmp="/tmp/watch.$(basename "$file")"


silently() {
	"$@" > /dev/null 2>&1
}

cleanup() {
	silently kill %%
	silently rm "$tmp"
}

trap 'cleanup; exit' INT TERM HUP


hms() {
	printf ' (at %s)' "$(date +%_H:%M:%S)"
}

title() {
	printf '\033]2;watchfile %s: %s%s\a' "$file" "$1" "$(hms)"
}

sgr() {
	printf '\033[%sm' "$1"
}

coloured() {
	sgr "$1"
	printf '%s' "$2"
	sgr 0
}


while true; do
	clear
	output=$("$@" "$file")
	ecode="$?"
	if [ "$ecode" = "0" ]; then
		colour=32 # green
		result="All good"
	else
		colour=31 # red
		result="Error"
	fi
	title "$result"
	if [ -z "$output" ]; then
		coloured "$colour" "$result"
		hms
	else
		echo "$output" > "$tmp"
		less "$tmp" &
	fi
	inotifywait --quiet --event modify "$file"
	cleanup
done