feat: Extend deploy.sh script

The deploy.sh script now allows to install the driver for either

    * all available kernels,
    * a specific kernel, or
    * the currently active kernel

In order to do so it got a small CLI that even prints a help text on
`--help`.

README.md

@@ -42,9 +42,17 @@ important work by saving and such beforehand.
 ### DKMS installation
 
 If you want to have the driver available at startup, it will be convenient to
-register it in DKMS. An executable explanation of how to do so can be found in
-the script `deploy.sh`. Since registering a kernel module in DKMS is a major
-intervention, only execute it if you understand what the script does.
+register it in DKMS. This can be done using the script `deploy.sh`, for either
+
+  * all kernels,
+  * a specific kernel, or
+  * the currently active kernel.
+  
+Please consult `--help` for more information and consider reading the script
+before executing it.
+
+Since registering a kernel module in DKMS is a major intervention, only execute
+it if you understand what the script does.
 
 ### Unknown Symbol Errors
 

deploy.sh

@@ -2,36 +2,108 @@
 
 set -euo pipefail
 
-function ensure_no_cli_args() {
-    if [ $# -ne 0 ]
-    then
-        echo "No command line arguments accepted!" >&2
-        exit 1
-    fi
-}
+TARGET_KERNEL=
+VERBOSE=false
 
-function ensure_root_permissions() {
-    if ! sudo -v
-    then
-        echo "Root permissions required to deploy the driver!" >&2
-        exit 1
-    fi
+function main() {
+    local VERSION
+    VERSION="$(get_version)"
+    parse-cli-args "$@"
+    ensure_root_permissions
+    put_sources_in_place "$VERSION"
+    deploy_driver "$VERSION"
 }
 
 function get_version() {
     sed -En 's/PACKAGE_VERSION="(.*)"/\1/p' dkms.conf
 }
 
-function deploy_driver() {
-    VER=$(get_version)
-    sudo rsync --delete --exclude=.git -rvhP ./ "/usr/src/rtl88x2bu-${VER}"
-    for action in add build install
-    do
-      sudo dkms "${action}" -m rtl88x2bu -v "${VER}"
+function parse-cli-args() {
+    while [[ $# -gt 0 ]]; do
+        case "$1" in
+            -v | --verbose)
+                VERBOSE=true
+                shift
+                ;;
+            -h | --help)
+                print-usage
+                exit 0
+                ;;
+            *)
+                if [[ -n "${TARGET_KERNEL}" ]]; then
+                    echo "Only one target kernel can be specified!" >&2
+                    exit 1
+                fi
+                TARGET_KERNEL="$1"
+                shift
+                ;;
+        esac
     done
+}
+
+function print-usage() {
+    cat <<EOF
+Usage: $0 [-v|--verbose|TARGET_KERNEL]..
+
+Deploy the rtl88x2bu driver to the system. If TARGET_KERNEL is not specified,
+the driver will be deployed to all available kernels.
+
+Options:
+  -h, --help        Show this help message and exit
+  -v, --verbose     Enable verbose output
+  TARGET_KERNEL     Specify the target kernel version to deploy the driver to.
+                    If not specified, the script will deploy to all available
+                    kernels.
+
+Examples:
+
+$0
+$0 -v \$(uname -r)
+$0 6.12.17-amd64
+
+This script will ask for root permissions to deploy the driver.
+EOF
+}
+
+function ensure_root_permissions() {
+    if ! sudo -v; then
+        echo "Root permissions required to deploy the driver!" >&2
+        exit 1
+    fi
+}
+
+function put_sources_in_place() {
+    local VERSION="$1"
+    sudo rsync --delete --exclude=.git -rvhP ./ "/usr/src/rtl88x2bu-${VERSION}" >/dev/null
+    log "Sources copied to /usr/src/rtl88x2bu-${VERSION}"
+}
+
+function deploy_driver() {
+    local VERSION="$1"
+    sudo dkms "add" -m rtl88x2bu -v "${VERSION}" || true
+    list-kernels |
+        while read -r kernel; do
+            for action in build install; do
+                sudo dkms "${action}" -m rtl88x2bu -v "${VERSION}" -k "${kernel}"
+            done
+        done
     sudo modprobe 88x2bu
 }
 
-ensure_no_cli_args "$@"
-ensure_root_permissions
-deploy_driver
+function list-kernels() {
+    if [[ -n "${TARGET_KERNEL}" ]]; then
+        echo "${TARGET_KERNEL}"
+    else
+        find /boot -maxdepth 1 -iname "initrd.img*" |
+            cut -d- -f2
+        echo "${TARGET_KERNEL}"
+    fi
+}
+
+function log() {
+    if [[ "$VERBOSE" = "true" ]]; then
+        echo "$1"
+    fi
+}
+
+main "$@"