`seq` and bash brace expansion failing

for i in {0..1000000} and for i in $(seq 1000000) both build up a big list and then loop over it. That's inefficient and uses a lot of memory.

Use:

for ((i = 0; i<= 1000000; i++))

instead. Or POSIXly:

i=0; while [ "$i" -le 1000000 ]; do
  ...
  i=$(($i + 1))
done

Or:

seq 1000000 | xargs...

---

To get a file full of CRLFs:

yes $'\r' | head -n 1000000 >  file

Generally, loops should be avoided when possible in shells.

@Stéphane Chazelas gave a great answer up there.

Mine is not an answer. I just it got curious about the efficiency of the different solutions, so I thought I should share my results...

~# i=0 ; time while [ "$i" -le 1000000 ]; do ((i++)) ;done
real    0m21.753s

~# time for ((i = 0; i<= 1000000; i++))  ;do : ;done
real    0m15.791s

~# time for i in {0..1000000} ;do : ;done
real    0m8.897s

~# time for i in $(seq 0 1000000) ;do : ;done
real    0m7.760s

:~# time seq 1000000 | xargs true
real    0m0.938s

~# time yes $'\r' | head -n 1000000 >/dev/null
real    0m0.048s

The yes answer is the clear winner. :-) Besides, it actually does the work that the OP needed.