如何拦截关机调用并运行脚本以允许或阻止关机？

Hey there! Given your scenario—your laptop has finicky hardware that needs multiple boot attempts, and you often forget to back up modified code to your USB drive—this pre-shutdown check setup is totally feasible. Below are step-by-step solutions for both Windows and Linux, the two most common desktop systems:

Windows Implementation #

1. Build Your Check Script (PowerShell Example) #

First, create a PowerShell script (let’s name it ShutdownCheck.ps1) that handles the core logic: checking for your USB drive, verifying code backups, and either canceling shutdown or letting it proceed.

Here’s a ready-to-adapt example:

# Check if your USB drive is connected (replace 'E:' with your actual USB drive letter)
$usbDrive = Get-Volume | Where-Object { $_.DriveLetter -eq 'E:' }
if (-not $usbDrive) {
    # Pop up a warning to insert the USB
    [System.Windows.MessageBox]::Show('Please insert your USB drive to back up modified code!', 'Shutdown Cancelled', [System.Windows.MessageBoxButton]::OK, [System.Windows.MessageBoxImage]::Warning)
    # Cancel the pending shutdown request
    shutdown /a
    exit
}

# Add your custom code backup check logic here
# This example compares local code files with their USB counterparts by modified time
$localCodeDir = "C:\Your\Code\Folder\Path"
$usbCodeDir = "E:\Your\Backup\Code\Folder"
$hasUnbackedChanges = $false

Get-ChildItem -Path $localCodeDir -Recurse -File | ForEach-Object {
    $usbFilePath = Join-Path -Path $usbCodeDir -ChildPath $_.FullName.Substring($localCodeDir.Length)
    if (-not (Test-Path $usbFilePath) -or $_.LastWriteTime -gt (Get-Item $usbFilePath).LastWriteTime) {
        $hasUnbackedChanges = $true
        return
    }
}

if ($hasUnbackedChanges) {
    [System.Windows.MessageBox]::Show('You have unbacked code changes! Please back them up first.', 'Shutdown Cancelled', [System.Windows.MessageBoxButton]::OK, [System.Windows.MessageBoxImage]::Warning)
    shutdown /a
} else {
    Write-Host 'All checks passed—shutdown can proceed.'
}

2. Trigger the Script on Shutdown #

We’ll use Task Scheduler to run this script whenever a shutdown request is made:

• Open Task Scheduler, click "Create Basic Task"
• Name it something like "Pre-Shutdown Code Backup Check", add a description if you want, then click Next
• For the trigger, select "When a specific event is logged", then Next
• Set Log to System, Source to User32, Event ID to 1074 (this ID corresponds to a system shutdown request), then Next
• For the action, select "Start a program", then Next
• In "Program/script", enter powershell.exe; in "Add arguments", enter -ExecutionPolicy Bypass -File "C:\Full\Path\To\ShutdownCheck.ps1" (replace with your script’s actual path), then Next
• Check "Open the properties dialog for this task when I click Finish", then click Finish
• In the properties window:
  • Go to the "Conditions" tab and uncheck "Wake the computer to run this task"
  • Go to the "Settings" tab and optionally check "If the task fails, restart every X minutes" (adjust the interval as needed)
  • Click OK to save

Linux Implementation #

1. Build Your Check Script (Bash Example) #

Create a Bash script (name it shutdown_check.sh) with similar logic—you’ll need a tool like zenity for pop-up prompts (install it first with sudo apt install zenity on Debian/Ubuntu, or equivalent for your distro).

Example script:

#!/bin/bash

# Check if your USB drive is mounted (replace /mnt/usb_backup with your actual mount point)
if ! mountpoint -q /mnt/usb_backup; then
    zenity --warning --text="Please insert and mount your USB drive to /mnt/usb_backup to back up code!"
    # Cancel the pending shutdown
    shutdown -c
    exit 1
fi

# Check for unbacked code changes
LOCAL_CODE="/home/your_username/code_directory"
USB_CODE="/mnt/usb_backup/code_backup"
has_unbacked=0

# Compare local and USB code directories
diff -rq "$LOCAL_CODE" "$USB_CODE" | grep -q "Only in $LOCAL_CODE"
if [ $? -eq 0 ]; then
    has_unbacked=1
fi

if [ $has_unbacked -eq 1 ]; then
    zenity --warning --text="You have unbacked code changes! Please back them up first."
    shutdown -c
else
    echo "All checks passed—shutdown can proceed."
fi

Make the script executable: chmod +x shutdown_check.sh

2. Trigger the Script on Shutdown #

We’ll use systemd to hook the script into the shutdown process:

• Create a systemd service file at /etc/systemd/system/shutdown-check.service with this content:

[Unit]
Description=Run pre-shutdown code backup check
DefaultDependencies=no
Before=shutdown.target reboot.target halt.target

[Service]
Type=oneshot
ExecStart=/full/path/to/shutdown_check.sh
TimeoutStartSec=0

[Install]
WantedBy=shutdown.target reboot.target halt.target

• Reload systemd to pick up the new service: sudo systemctl daemon-reload
• Enable the service so it runs automatically on shutdown/reboot: sudo systemctl enable shutdown-check.service

Quick Notes #

• Don’t forget to replace placeholder paths (like USB drive letters/mount points, code directories) with your actual setup
• On Windows, if PowerShell blocks script execution, you can run Set-ExecutionPolicy RemoteSigned in an admin PowerShell window to loosen restrictions (the script uses -ExecutionPolicy Bypass to bypass per-run checks too)
• On Linux, if you don’t want graphical prompts, you can replace zenity with text-based alerts (like echo to the terminal, though this only works if you’re logged in locally)

内容的提问来源于stack exchange，提问作者Karim Mtl