Bash Number Limit?

Question

I asked a question earlier that involved pulling large primes from a text file and putting them into another file. It was supposed to grab every prime up to and including the first prime after 2^32, and for some reason this script stopped working.

#!/bin/bash
n=4294967296
last=0
while read number
    do
    if [ $last -gt $n ]
    then break
    fi
    echo $number
last=$number
done < primes.txt > primes2.txt

It ended up looping through these 11 numbers:

4232004449  
4232004479  
4232004493  
4232004509  
4232004527  
4232004533  
4232004559  
4232004589  
4232004593  
4232004613  
004437

The original file didn't have 004437 in it, and my bash will handle numbers over 8999999999999999999

Does anybody have a clue as to why this happened?

64-bit Ubuntu 10.04, 16GB RAM, 8-cores @ 3.60 GHz
GNU bash, version 4.1.5(1)-release (x86_64-pc-linux-gnu)

Update:

After downloading and compiling the "fixed" bash provided by jfgagne and linking to it in my bash script, it errored out at the same exact spot. Using the significantly faster perl equivalent from my original prime question, I got some file sizes from ls -al:

        11  next_prime (just to make sure this was counting bytes accurately)
2147483659  primes2.txt
2147483670  one_too_many

2147483659 = 2^31 + 11

The size of the next prime (4232004631) is 11 bytes This holds all primes up to 4232004613. I also realized that the 004437 is coming from the end of the prime at the bottom of this error loop (4232004437). It seems like something is trying to advance, but stuck.

Answer 1

No, it is independent from the bitsize of your OS. It depends upon a simple declaration deep in the bash sources.

This declaration is __int64_t since around 2002. Since then, bash versions >= 3.00 always use 64bit integer variables, and it doesn't depend on the architecture! It only depends on the bash version.

Previous versions of bash used always 32 bit integer, even on 64 bit OS.