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

Question

Im learning shell scripting from an outdated textbook, and it seems to me like it'd be really usefull to have a program that just returns a string of numbers delimited by spaces something like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

Answer 1

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

Answer 2

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.

Answer 3

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}'

Answer 4

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

Answer 5

Use a for loop

for ((i = 10; i <= 20; ++i)); do
    printf '%d\n' "$i"
done

Answer 6

For the sake of completeness here something that will work with some older variants of Unix (as long as they have perl installed). Not really elegant.

for I in $(perl -e 'print join("\n", 1..10)'); do something with $I; done

Answer 7

You can use seq, or if you don't have that, you can write it yourself:

#!/bin/bash
[ $# -ge 1 ] || { echo "Usage: seq Number [ Number ]" 1>&2 ; exit 1; }
[ $# -eq 1 ] && { [ $1 -gt 1 ] && ./seq $(($1 - 1)) ; echo $1 ; }
[ $# -eq 2 ] && { [ $(($2 - $1)) -gt 0 ] && ./seq $1 $(($2 - 1)) ; echo $2 ; }

Usage:

$ ./seq 3
1
2
3

Or:

$ ./seq 3 7
3
4
5
6
7