sh shell for loop without seq

Question

I'm writing a script that must work in bash and sh and it runs on a miniscule platform and some things appear to be missing such as seq. All these limitations/requirements is making writing this script VERY difficult. I need to write a for loop that works under all these requirements.

This only works for bash:

for (( i = 0; i <= 4; i++ ))
do
  echo $i
done

This should work in sh, but the platform I'm using is apparently missing seq.

for i in $(seq 1 $INPUT); do

$INPUT is the max defined by the user.

@Joel, just check what is your /bin/sh stands for. E.g. on debian systems it is mostly linked to `dash` and `dash` doesn't support `for (())` contrsuction. — rush, Jul 22 '14 at 21:08

score 16 · Answer 1 · answered Jul 22 '14 at 21:05

16

Kids these days are so spoiled with their newfangled shell builtins.

i=1
while [ $i -le $INPUT ]; do
  echo $i
  i=$(expr $i + 1)
done

answered Jul 22 '14 at 21:05

Sammitch

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8

extra +1 for "cranky" – glenn jackman Jul 22 '14 at 21:11
3

It's very likely the shell is at least POSIX-conforming, so you can use `i=$((i+1))` instead of `expr`. – chepner Jul 22 '14 at 21:42

sh shell for loop without seq

1 Answers1