Bash Number Limit?
bash, linux, numbers
Solution
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.
Problem
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.