Is there a standard unix program that returns a range of numbers

Im learning shell scripting from an outdated textbook, and it seems to me like it'd be really usefull to have a program that just returns a string of numbers delimited by spaces something like

$ range 10 20
10 11 12 13 14 15 16 17 18 19 20

Then, if youre doing a shell script you can have

for i in `range 10 20`; do some stuff with numbers in that range;done

does such a thing exist, or do I need to write it myself?

seq is part of coreutils.

for i in $( seq 1 2 11 ) ; do echo $i ; done

Output:

1
3
5
7
9
11

If you provide only 2 arguments to seq, the increment is 1:

$ seq 4 9
4
5
6
7
8
9

Would Bash suffice?

for i in {10..20}; do echo $i; done

You can do a lot of things with brace expansion. Bash 4 also supports padded ranges, e.g. {01..20}.

Note that Bash is not considered portable, and not a standard Unix utility. Although you can safely assume that it is installed on most modern Linuxes, don't use this in a script that you plan to run on all kinds of Unix-like machines.

If you want something strictly portable (i.e. that does not rely on specific bash extensions or commands not specified by POSIX)

awk 'BEGIN {for(i=10;i<=20;i++) printf "%d ",i; print}'

Before 10.7 there was no seq on Mac OS X, but jot, due to the BSD heritage.

jot -- print sequential or random data

...

HISTORY
    The jot utility first appeared in 4.2BSD

Example:

$ jot - 1 3
1
2
3