磁盘空间使用脚本错误 [英] Error on a disk space usage script

问题描述

我试图修改一些检查磁盘空间使用情况的脚本，但遇到以下错误：

I tried to modify a little script of checking disk space usage, and I faced the below error:

disk_space.sh： 32：[：使用：期望整数表达式

disk_space.sh: line 32: [: Use: integer expression expected

# Set alert limit, 90% we remove % for comparison
alert=90

# $1 is the partition name
# $5 is the used percentage
# Print the df -h, then loop and read the result 
df -h | awk '{ print $1 " " $5 }' | while read output;
do

#echo $output

# Get partition name
partition=$(echo $output | awk '{ print $1 }')
#echo 'Partition: ' $partition

# Used space with percentage
useSpPer=$(echo $output | awk '{ print $2}')
#echo 'Used space %: ' $useSpPer

#used space (remove percentage)
useSp=$(echo -n $useSpPer | head -c -1)
#echo 'Used space digit: ' $useSp

# Recap
#echo $useSp ' has ' $partition

# -ge is greatter than or equal
if [ $useSp -ge $alert ]; then # THIS LINE 32
echo $partition 'is running out of space with '$useSpPer

#else 
#echo 'Down'

fi
done

如果有人有想法，请先感谢并感谢

If anyone has an idea, appreciated it and thanks in advance

推荐答案

在脚本的顶部放置 set -x ，使其回显每一行在执行之前，这是调试Shell脚本的好方法-您几乎可以肯定会发现，这些变量之一（用于 [命令中）未按预期设置

Putting set -x at the top of your script so that it echoes each line before execution is a great way to debug shell scripts - you'll almost certainly find that one of those variables (used in the [ command) isn't being set as you expected.

这是一个很好的一般建议，但是，对于您已将问题定位到该问题的位置，将这一行放在行前可能已经足够好了（当然也不太冗长）。产生问题：

That's good general advice but, for this problem where you've localised the problem, it's probably good enough (and certainly less verbose) to place this line before the line generating the problem:

echo "DEBUG [$useSp]"

如果这样做，您会发现所检查的值根本不是数字值。这是因为 df -h 的输出看起来像这样：

If you do that, you'll find that the value you're checking is not a numeric value at all. That's because the output of df -h looks something like this:

Filesystem  Size  Used  Avail  Use%  Mounted on
/dev/sda1    48G  4.9G    40G   11%  /
/dev/sr0     71m   71M      0  100%  /media/cdrom0

这意味着，对于第一行，您将把 Use 与您的限额和 [不能很好地处理：

That means that, for the first line, you'll be comparing the word Use against your limit and [ will not handle that well:

pax> if [ 20 -gt 10 ]; then echo yes; fi
yes
pax> if [ Use -gt 10 ]; then echo yes; fi
bash: [: Use: integer expression expected

修复非常简单。由于您不想对第一行进行任何操作，因此只需使用现有的 awk 即可将其过滤掉：

The fix is fairly simple. Since you don't want to do anything with the first line, you can just use your existing awk to filter it out:

df -h | awk 'NR>1{print $1" "$5}' | while read output;
do
    ...

NR> 1 仅处理记录数字2，依此类推，跳过第一个。

The NR>1 only processes record numbers two and so on, skipping the first one.

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