promote eval-on-empty-stdin, eval-on-not-empty-stdin

commands/eval-on-empty-stdin

@@ -0,0 +1,71 @@
+#!/usr/bin/env bash
+
+function eval_on_empty_stdin() (
+	source "$DOROTHY/sources/bash.bash"
+
+	# =====================================
+	# Arguments
+
+	function help {
+		cat <<-EOF >/dev/stderr
+			ABOUT:
+			Execute the <command> if stdin is empty; stdin content will continue to be directed to stdout.
+			Companion to [eval-on-not-empty-stdin].
+
+			USAGE:
+			eval-on-empty-stdin [--] ...<command>
+		EOF
+		if [[ $# -ne 0 ]]; then
+			echo-error "$@"
+		fi
+		return 22 # EINVAL 22 Invalid argument
+	}
+
+	# process
+	local item option_cmd=()
+	while [[ $# -ne 0 ]]; do
+		item="$1"
+		shift
+		case "$item" in
+		'--help' | '-h') help ;;
+		'--')
+			option_cmd+=("$@")
+			shift $#
+			break
+			;;
+		'--'*) help "An unrecognised flag was provided: $item" ;;
+		*)
+			option_cmd+=("$item" "$@")
+			shift $#
+			break
+			;;
+		esac
+	done
+
+	# =====================================
+	# Action
+
+	# doesn't work:
+	# if read -r; then
+	# 	__print_lines 'not empty'
+	# else
+	# 	__print_lines 'empty'
+	# fi
+
+	# doesn't work:
+	# if [[ -t 0 ]]; then
+	# 	__print_lines 'empty'
+	# else
+	# 	__print_lines 'not empty'
+	# fi
+
+	# works:
+	setup-util-moreutils --quiet # ifne
+	ifne -n "${option_cmd[@]}"
+	return
+)
+
+# fire if invoked standalone
+if [[ $0 == "${BASH_SOURCE[0]}" ]]; then
+	eval_on_empty_stdin "$@"
+fi

commands/eval-on-not-empty-stdin

@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+
+function eval_on_not_empty_stdin() (
+	source "$DOROTHY/sources/bash.bash"
+
+	# =====================================
+	# Arguments
+
+	function help {
+		cat <<-EOF >/dev/stderr
+			ABOUT:
+			Execute the <command> if stdin is not empty; the stdin content will still be available to whatever eventually reads it.
+			Companion to [eval-on-empty-stdin].
+
+			USAGE:
+			eval-on-not-empty-stdin [--] ...<command>
+		EOF
+		if [[ $# -ne 0 ]]; then
+			echo-error "$@"
+		fi
+		return 22 # EINVAL 22 Invalid argument
+	}
+
+	# process
+	local item option_cmd=()
+	while [[ $# -ne 0 ]]; do
+		item="$1"
+		shift
+		case "$item" in
+		'--help' | '-h') help ;;
+		'--')
+			option_cmd+=("$@")
+			shift $#
+			break
+			;;
+		'--'*) help "An unrecognised flag was provided: $item" ;;
+		*)
+			option_cmd+=("$item" "$@")
+			shift $#
+			break
+			;;
+		esac
+	done
+
+	# =====================================
+	# Action
+
+	setup-util-moreutils --quiet # ifne
+	ifne "${option_cmd[@]}"
+)
+
+# fire if invoked standalone
+if [[ $0 == "${BASH_SOURCE[0]}" ]]; then
+	eval_on_not_empty_stdin "$@"
+fi