Replace a string in a file with a 1D array--please don't close it

Hi all,

Please help me with this question. I have been trying to find a simple way to do so. Please don't close this.

I have a 1D number array with N numbers say A=[1,2,3,4,5,6,7,8,9,10,...100]; I have a text file 'Test.txt'. Inside the text file I have a string [$1].

 Data
 [$1]
 /

How to replace the string [$1] with the content of the array A in such a way that the array content is written one after each other in multiple lines where only 6 space-delimited numbers are printed in each line except the last line that could be shorter than 6 numbers (depending on the size of A). After this I would like to save the file with other name say 'Test1.txt' with the following contents:

 Data
 1  2  3 4  5  6
 7  8  9  10  11  12
 13 14 15 16  17  18
 ...
/