[Buildroot] [git commit master 1/1] genext2fs.sh: improve number of blocks calculation

[Yann E. MORIN]

Peter, All,

On Thursday 30 December 2010 23:10:21 Peter Korsgaard wrote:
> +    BLOCKS=$(expr 500 + \( $BLOCKS + $INODES / 8 \) \* 11 / 10)

POSIX specifies that you can do arithmetics in the shell:

2.6.4 Arithmetic Expansion

  Arithmetic expansion provides a mechanism for evaluating an arithmetic
  expression and substituting its value. The format for arithmetic expansion
  shall be as follows:

  $((expression))

You do even need to do variable expansion, it's implicit when doing
arithmetics expansion:

  If the shell variable x contains a value that forms a valid integer
  constant, then the arithmetic expansions "$((x))" and "$(($x))" shall
  return the same value.

So I'd write that as:

  BLOCKS=$(( 500 + (BLOCKS+INODES/8) * 11 / 10 ))

Much more readable, IMHO.

Regards,
Yann E. MORIN.

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