sed replace string from file with content from another file

Question

I want to replace string from file with content from another file

File 1: T1.txt

TEXT1  
TEXT2  
TEXT3  
TEXT4  

File 2: T2.txt

Line with PLACEHOLDER
Line with PLACEHOLDER
Line with PLACEHOLDER
Line with PLACEHOLDER

I want to replace "PLACEHOLDER" string from "File 2" with all contents from "File 1", no matter if it create new file or change in existing file.

I tried:-

sed -i -e '/PLACEHOLDER/ r T2.sql' -e s/PLACEHOLDER// T1.sql

not working not sure why

Answer 1

This will insert a newline before the included text, and does not handle text that may follow PLACEHOLDER:

sed -e '/PLACEHOLDER/{ s///; rT1.txt
}'  T2.txt

To avoid the additional newline and to handle PLACEHOLDER in the middle of a line, you could do:

perl -MFile::Slurp -pe 'BEGIN{$r=read_file("T1.txt")} s/PLACEHOLDER/$r/g' T2.txt

You probably (almost certainly) can make sed do the inline substitution of a multiline value, but sed really is line oriented and any such solution would require more gymnastics than using enhanced sed (aka, perl).