kernel.sh: Add error helper function

README.org

@@ -11,3 +11,9 @@ Disables incomplete reports in ~i2c-hid-code.c~ to stop logging spam.
 $ mkdir build
 $ ./kernel.sh
 #+END_SRC
+
+* Install
+
+#+BEGIN_SRC sh
+$ ./kernel.sh install
+#+END_SRC

kernel.sh

@@ -5,7 +5,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 #
 # Build the Linux kernel
-# Depends: asp, base-devel
+# Depends: asp, base-devel, coreutils
 
 # Setup
 # --------------------------------------
@@ -16,19 +16,51 @@ blue="$(tput setf 1)"
 red="$(tput setf 4)"
 n="$(tput sgr0)"
 
-if [ "$(dirname "$0")" != "." ]; then
+error()
-	echo "${b}${red}Error:${n} please run this script from the directory it resides." >&2
+{
+	echo "${b}${red}Error:${n} $1" >&2
 	exit 1
+}
+
+if [ "$(dirname "$0")" != "." ]; then
+	error "please run this script from the directory it resides."
 fi
 
+help()
+{
+	cat << EOF
+${b}NAME${n}
+	kernel.sh - build the Linux kernel
+
+${b}SYNOPSIS${n}
+	${u}kernel.sh${n} [${u}OPTION${n}] ${u}COMMAND${n}
+
+${b}OPTIONS${n}
+	${b}-h${n}, ${b}--help${n}	Display usage message and exit.
+
+${b}COMMANDS${n}
+	${b}build${n}
+		Build the kernel, this is the default.
+
+	${b}install${n}
+		Install the kernel.
+EOF
+}
+
 # Main functionality
 # --------------------------------------
 
 cdSafe()
 {
 	if ! cd "$1" 2> /dev/null; then
-		echo "${b}${red}Error:${n} no such file or directory: $1" >&2
+		error "no such file or directory: $1"
-		exit 1
+	fi
+}
+
+fileExist()
+{
+	if [ ! -f "$1" ] ; then
+		error "no such file or directory: $1"
 	fi
 }
 
@@ -37,12 +69,12 @@ checkDependencies()
 	dependencies="
 		asp
 		base-devel
+		coreutils
 	"
 
 	for dependency in $dependencies; do
 		if ! pacman -Qs "$dependency" > /dev/null; then
-			echo "${b}${red}Error:${n} required dependency '$dependency' is missing." >&2
+			error "required dependency '$dependency' is missing."
-			exit 1
 		fi
 	done
 }
@@ -54,14 +86,14 @@ build()
 	rm -rf "./linux"
 	asp update linux
 	asp export linux
-	[ -f linux/config ] && mv linux/config .
+	fileExist linux/config && mv linux/config .
-	[ -f linux/PKGBUILD ] && mv linux/PKGBUILD .
+	fileExist linux/PKGBUILD && mv linux/PKGBUILD .
 	rm -rf "./linux"
 
 	patch --forward --strip=1 config < ../patch/config.patch
 	patch --forward --strip=1 PKGBUILD < ../patch/pkgbuild.patch
 
-	ln -s ../patch/i2c-hid-disable-incomplete-reports.patch .
+	ln -s ../patch/i2c-hid-disable-incomplete-reports.patch . 2> /dev/null
 
 	updpkgsums
 
@@ -74,8 +106,43 @@ build()
 	time makepkg -s
 }
 
+install()
+{
+	cdSafe build
+
+	packages="$(find . -name "*.tar.zst" -type f)"
+
+	found="$(echo "$packages" | wc -l)"
+	if [ "$found" -ne 2 ]; then
+		error "kernel was not build yet."
+	fi
+
+	if ! sudo -v; then
+		error "you cannot perform this operation uness you are root."
+	fi
+
+	echo "$packages" | xargs --open-tty sudo pacman -U --needed
+}
+
 # Execute
 # --------------------------------------
 
 checkDependencies
+
+script="$(basename "$0")"
+case "$1" in
+	-h | --help)
+		help
+		;;
+	build | "")
 		build
+		;;
+	install)
+		install
+		;;
+	*)
+		echo "$script: invalid option '$1'" >&2
+		echo "Try '$script -h' for more information." >&2
+		exit 1
+		;;
+esac