Append strings to lines with looping over

Question

I have a file :

aaa
bbb
ccc

and another one:

111
222
333
444
.
.
999

My desired output after appending should be :

aaa 111
bbb 222 
ccc 333 
aaa 444
bbb 555
ccc 666
.
.
.
aaa nnn

I can append fixed strings with awk and sed, but I'm not able to figure out the looping over a fixed number of lines with different strings. While the second long file exists as a file, the strings to append don't have to be in a file, but since it is 11 lines of looping in the real case, I assume another file is the right ay to read them in.

Answer 1

With sed, bash, a function and two global variables (counter and f1).

counter=1
getnext() {
  f1=$(sed -n "${counter}p" file1)
  if [[ "$f1" == "" ]]; then
    counter=1
    f1=$(sed -n "${counter}p" file1)
  fi
  ((counter++))
}

while read -r f2; do getnext; echo "$f1 $f2"; done <file2

Output:

aaa 111
bbb 222
ccc 333
aaa 444
bbb 555
ccc 666
aaa 777
bbb 888
ccc 999

Answer 2

A solution with awk. The prepending file (that goes to the first column) is loaded to the array arr at BEGIN section. The - (stdin) can be replaced by the file name.

The second file is the normal awk input.

echo -e 'a\nb\nc'|
awk 'BEGIN {
        while ((getline < "-") > 0) {
                arr[i++] = $0
        }
}

{
        if (j in arr) {
                print arr[j++], $0
                next
        }
        j = 0
        print arr[j++], $0
}' <(echo {1..10}|tr ' ' '\n')