Shell Programming and Scripting

I do have a file of the following format

file 1

Code:

>SAM
ATGCTCCTTAGCTACGTAGCAAGTAGAAAAAA
AGCGCGAGCATTGAAGCGGAGGAGAGGAGGA
TGAGATGATGACCCAGTATAAAGAGTGATGAT

like this above file. file 1 has 1000's of lines. I would like to edit this file1 using the information from file2 (see below), by replacing the 4th alphabet or alphabet at the position 4 C with T; 10th position alphabet A to C ......61th position alphabet G to A and 66th position alphabet A to C.
file 2

Code:

4 C T
10 A C
19 G A
38 G T
61 G A
66 A C

I am expecting the output file, file 3 with the edits.

Code:

>SAM
ATGTTCCTTCGCTACGTAACAAGTAGAAAAAA
AGCGCTAGCATTGAAGCGGAGGAGAGGAAGA
TGCGATGATGACCCAGTATAAAGAGTGATGAT

Please let me know the best way edit this file1 and create the new file 3 using awk or sed or perl

Your data doesn't looks like having length of 66 , as per the question.

No it doesn't have a length of 66. In the second file, file2 shows the position on file1 where the edits has to be done. The actual file have 1000's of letters. Hope this helps

What have you tried?

first split the string with perl (see example 4 here) then check and replace according to position and letter ...

Your sample output file does by no means fit the edits defined in file 2 applied to file1, e.g. line 2 pos 10 should have become a C; and where does line 2 pos 29 A come from?
Please post representative samples, and your solution attempts so far.

Counts don't go for each line. It starts from position 1 and goes continuously to the end of the file. It is not counted separately for each line. Hope this makes it clearer. I tried to put in it all in a hash using perl but was not successful in getting the output