Convert range to string

Question

If I run the

echo {0..9}

command, then I get the following output:

0 1 2 3 4 5 6 7 8 9

Can I somehow put the string "0 1 2 3 4 5 6 7 8 9" into a variable inside bash script? I only found a way using echo:

x=`echo {0..9}`

But this method implies the execution of an external program. Is it possible to somehow manage only with bash?

Interested, rather than a way to convert a range to a string, but additionally concatenate with a string, for example:

datafiles=`echo data{0..9}.txt`

Answer 1

First of all,

x=`echo {0..9}`

doesn't call an external program (echo is a built-in) but creates a subshell. If it isn't desired you can use printf (a built-in as well) with -v option:

printf -v x ' %s' {0..9}
x=${x:1} # strip off the leading space

or

printf -v datafiles ' data%s.txt' {0..9}
datafiles=${datafiles:1}

or you may want storing them in an array:

datafiles=(data{0..9}.txt)
echo "${datafiles[@]}"

This last method will work correctly even if filenames contain whitespace characters:

datafiles=(data\ {0..9}\ .txt)
printf '%s\n' "${datafiles[@]}"