I'm trying to write a simple script that utilizes the `du` command, but I'm running into an issue with floating point math. I'm getting an error when I try to perform a calculation with a decimal, specifically: `arithmetic syntax error: invalid arithmetic operator (error token is ".6")`. However, when I run the same script directly in the terminal, it works fine. I'm using Zsh, but I've also tried running it with Bash. The problem line is:`echo " $((237 - $(cat $SC/tmp/du)))"`. Here's my complete script for context.
4 Answers
If you're only looking at file system usage, consider using `df /` or `df -BG /`. It directly gives you the numbers you need without any decimal issues.
Bash doesn't support floating point arithmetic directly. You should pipe the output to a tool like `bc` or `awk` instead. For example:
```bash
echo "237 - $(cat $SC/tmp/du)" | bc
``` Just make sure to format the command properly.
You should use `bc` for calculations involving floating points. Here's how it would look:
```bash
x=10
y=20
z=$(echo "$x + $y" | bc)
echo "z: $z"
``` That way, you can handle decimals without running into syntax errors.
If you're still facing issues after piping to `bc`, double-check your command. You might be inadvertently trying to perform the calculation in Bash itself. Instead, try this:
```bash
echo "237 - $(cat $SC/tmp/du)" | bc
``` This way, you're passing the whole string into `bc` for evaluation.
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