How to replace a value with the output of a command in a text file?

Question

I have a file that contains:

I want to replace in bash, the value 0

Answer 1

When the replacement string has newlines and spaces, you can use something else. We will try to insert the output of ls -l in the middle of some template file.

awk 'NR==FNR {a[NR]=$0;next}
    {print}
    /Insert index here/ {for (i=1; i <= length(a); i++) { print a[i] }}'
    <(ls -l) template.file

or

sed '/^Insert after this$/r'<(ls -l) template.file