Combining files in a directory by header and omitting shared content

Question

so I have found a question on here that is the opposite of what I would like to do here: Concatenate multiple files with same header.

I am trying to merge or concatenate 2 files,within a directory within hundred of files that have a counterpart file with the same substring, into one file based on the '>' character in the header. There are thousands of headers within the each file and as opposed to the question asked in the link I attached, the contents other than the header are the same so I don't want to change anything but every line that begins with '>'.

Essentially I would like to combine file1 to file2 by the shared character '>' and to leave the contents of file 1 in order.

File1
> MGBNCNOSNC_142
9u2o4840204a9
> MGBNCNOSNC_143
AOISCJNWDCSNDCCW
> MGBNCNOSNC_144
AOISCJ40204DZZW

---

File2
>King_Henry
>Queen_jerry
>Jack_jill

---

Output
> MGBNCNOSCNC_142 > King_henry
9u2o4840204a9
> MGBNCNOSCNC_143 > Queen_jerry
AOISCJNWDC
> MGBNCNOSNC_144 > Jack_jill
gefSCJ40204DZZW

Thanks for any help and let me know if I can be any clearer!

Answer 1

You could read the lines of File2 into an indexed awk array, and then append them in turn to the corresponding lines of File

awk '
  NR==FNR {a[i++]=$0; next} 
  /^>/ {$0 = $0" "a[j++];}
  {print}
  ' File2 File1

Alternatively, if you have GNU sed (with the R extension) you could try

sed '/^>/ R File2' File1 | sed '/^>/ {N;s/\n/ /}'

If your File1 has exactly one additional line for every line that is to be matched, another option might be to double space File2 and then paste the files together

sed 'G' File2 | paste -d ' ' File1 -

although that will result in an additional trailing space in the non-matching lines; if that's undesirable, you could insert a space at the start of each File2 line and paste them without a delimiter

sed 's/^/ /; G' File2 | paste -d '' File1 -