Problem to be solved - I was looking for a way to insert a line into a file ( it's actually related to Terraform but, for the purpose of illustration, it's just a text file ), using sed.
Here's a sample text file: -
cat simpsons.txt
Bart
Homer
Lisa
Maggie
Marge
Homer
Lisa
Maggie
Marge
and I want to add a new cast member called, imaginatively, "Dave" into the list, between "Bart" and "Homer".
Here's how I can do it in sed : -
sed -i'''/^Bart/a Dave' simpsons.txt
cat simpsons.txt
Bart
Dave
Homer
Lisa
Maggie
Marge
Of course, with a basic list of text, I could've just as easily appended "Dave" to the list, and sort it: -
echo "Dave">> simpsons.txt && sort simpsons.txt --output simpsons.txt
cat simpsons.txt
Bart
Dave
Homer
Lisa
Maggie
Marge
but that doesn't work too well with a structured file.
Let's use a Terraform file for illustration: -
cat version.tf
terraform {
required_providers {
aws = {
version = ">= 2.7.0"
source = "hashicorp/aws"
}
}
}
where I want to insert backend "s3" immediately after terraform but indented with two spaces: -
sed -i'''/^terraform/a \ \ backend "s3" {}' version.tf
which results in a nicely updated file: -
cat version.tf
terraform {
backend "s3" {}
required_providers {
aws = {
version = ">= 2.7.0"
source = "hashicorp/aws"
}
}
}
I <3 sed