sed append text obtained from stdout

Question

I know sed can append text in a few different ways:

1. to append the string NEW_TEXT:

   sed -i '/PATTERN/ a NEW_TEXT' file
   

2. to append contents of file file_with_new_text:

   sed -i '/PATTERN/ r file_with_new_text' file
   

However, is there anyway to append text piped to sed via stdout? I am hoping to obtain the equivalent of:

# XXX,YYY,ZZZ are line numbers
# The following appends lines XXX-YYY in file1
# after line ZZZ in file2.

sed 'XXX,YYY p' file1 > /tmp/file
sed -i 'ZZZ r /tmp/file' file2

without having to use a temporary file. Is this possible?

Answer 1

You can read from /dev/stdin. Clearly, this will only work once per sed process.

Example:

$ cat file1
this is text from file1
etc

$ cat file2
Hello world from file2

$ sed -n '1p' file1 | sed -i '$ r /dev/stdin' file2

$ cat file2
Hello world from file2
this is text from file1

Answer 2

You can use redirection operator with r command:

sed -i '/ZZZ/r '<(sed -n '1p' file1) file2