如何使用df -h、awk等工具为/mnt/hgfs创建自定义告警列

Perfect, let's build this custom disk alert for /mnt/hgfs using the tools you mentioned. Here's a clean, functional one-liner that does exactly what you need, plus I'll break down each part so you understand how it works:

df -h /mnt/hgfs | tail -n +2 | tr -s ' ' | awk '{
    usage = substr($5, 1, length($5)-1)
    if (usage >= 75 && usage <= 80) alert = "Warning"
    else if (usage >= 81 && usage <= 95) alert = "Critical"
    else if (usage > 95) alert = "Alarm"
    else alert = "OK"
    print $0, "\t", alert
}'

Breakdown of Each Component #

Let's walk through what each tool is doing here:

• df -h /mnt/hgfs: Fetches human-readable disk usage stats specifically for the /mnt/hgfs mount point. The -h flag ensures sizes are displayed in GB/MB instead of raw blocks, making it easier to read.
• tail -n +2: Skips the first header line of df's output (since we only care about the actual data row for /mnt/hgfs).
• tr -s ' ': Compresses multiple consecutive spaces into a single space. df uses variable spacing between columns, which can throw off awk's field detection—this small fix ensures each column is recognized correctly.
• awk (the core logic):
  • Extracts the numeric usage value: substr($5, 1, length($5)-1) strips off the % symbol from the 5th column (the usage percentage), turning it into a number we can compare directly.
  • Runs conditional checks to set the alert status based on your thresholds:
    • 75-80% → Warning
    • 81-95% → Critical

    • 95% → Alarm

    • All other values → OK
  • Prints the original disk stats followed by a tab-separated alert status for clean, readable output.

Bonus: Include a Custom Header #

If you want to keep the original df header and add an "Alert" column to make the output more structured, use this modified version:

df -h /mnt/hgfs | tr -s ' ' | awk '
    NR == 1 {print $0, "\t", "Alert"; next}
    {
        usage = substr($5, 1, length($5)-1)
        if (usage >=75 && usage <=80) alert="Warning"
        else if (usage >=81 && usage <=95) alert="Critical"
        else if (usage >95) alert="Alarm"
        else alert="OK"
        print $0, "\t", alert
    }
'

This will output a proper table with headers like Filesystem Size Used Avail Use% Mounted on Alert, making it even easier to parse at a glance.

内容的提问来源于stack exchange，提问作者John Rudolph