From 849bb66b5596e6f0414f00ce3e6a7925febc9134 Mon Sep 17 00:00:00 2001
From: hygienic-books <hygienic-books@tentic.net>
Date: Sun, 19 Mar 2023 21:35:59 +0100
Subject: [PATCH] feat(script): Initial commit

---
 README.md               | 22 +++++++++++++++++++++-
 arch-needs-restart.hook | 11 +++++++++++
 arch-needs-restart.sh   | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 64 insertions(+), 1 deletion(-)
 create mode 100644 arch-needs-restart.hook
 create mode 100755 arch-needs-restart.sh

diff --git a/README.md b/README.md
index 12f7d5f..4714fce 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,23 @@
 # arch-needs-restart
 
-A helper script to check which updated libraries and kernel are in use and require a restart
\ No newline at end of file
+A helper script to check which updated libraries and kernel are in use and require a restart
+
+# Setup
+
+Get started like so:
+
+1. Clone repo into arbitrary path `<repo>`
+1. Make `needs-restart.sh` executable
+    ```
+    chmod +x <repo>/needs-restart.sh
+    ```
+1. Symlink to files, for example
+    ```
+    sudo ln -s <repo>/needs-restart.sh /usr/local/bin/arch-needs-restart
+    sudo ln -s <repo>/arch-needs-restart.hook /usr/share/libalpm/hooks/arch-needs-restart.hook
+    ```
+    Note that while you may choose arbitrary locations for symlinks `arch-needs-restart.hook` references `/usr/local/bin/arch-needs-restart`. Change that accordingly if you need to.
+
+# Credits
+
+[StackExchange user Christian Zangl](https://unix.stackexchange.com/users/46158/laktak) aka `laktak` in January 2021 post [unix.stackexchange.com/a/630982](https://unix.stackexchange.com/a/630982)
diff --git a/arch-needs-restart.hook b/arch-needs-restart.hook
new file mode 100644
index 0000000..a72eb94
--- /dev/null
+++ b/arch-needs-restart.hook
@@ -0,0 +1,11 @@
+[Trigger]
+Operation = Install
+Operation = Upgrade
+Operation = Remove
+Type = Package
+Target = *
+
+[Action]
+Description = Check if anything's using outdated libs or kernel
+When = PostTransaction
+Exec = /usr/local/bin/arch-needs-restart
diff --git a/arch-needs-restart.sh b/arch-needs-restart.sh
new file mode 100755
index 0000000..c7b4949
--- /dev/null
+++ b/arch-needs-restart.sh
@@ -0,0 +1,32 @@
+#!/bin/bash
+
+get_boot_kernel() {
+    local get_version=0
+    for field in $(file /boot/vmlinuz*); do
+        if [[ $get_version -eq 1 ]]; then
+            echo $field
+            return
+        elif [[ $field == version ]]; then
+            # the next field contains the version
+            get_version=1
+        fi
+    done
+}
+
+rc=1
+
+libs=$(lsof -n +c 0 2> /dev/null | grep 'DEL.*lib' | awk '1 { print $1 ": " $NF }' | sort -u)
+if [[ -n $libs ]]; then
+    cat <<< $libs
+    echo "# LIBS: reboot required"
+    rc=0
+fi
+
+active_kernel=$(uname -r)
+current_kernel=$(get_boot_kernel)
+if [[ $active_kernel != $current_kernel ]]; then
+    echo "$active_kernel < $current_kernel"
+    echo "# KERNEL: reboot required"
+    rc=0
+fi
+exit $rc