shuf with interval is very inefficient and slow

[xelan]

Apparently, the implementation of the shuf command requires a lot of memory, as it creates a "virtual line" for each number in the range. For larger numbers (but well below INT_MAX) the command crashes with an "out of memory" error:

# about half of 32-bit INT_MAX
$ shuf -i 1-2222222222 -n 1
shuf: out of memory

For smaller numbers, the performance is worse than the GNU shuf binary by many orders of magnitude.

busybox shuf:

$ time shuf -i 1-99999999 -n 1
28235271

real	0m2.087s
user	0m1.588s
sys	0m0.424s

GNU shuf:

$ time shuf -i 1-99999999 -n 1
13884991

real	0m0,001s
user	0m0,000s
sys	0m0,001s

Thanks for investigating on this issue!

[robang74]

Can you write a patch, please?