how to insert tab in sed command? - sed

Question

I have a text file in which there's a YAML formatted code. Here's the code:
trigger:
branches:
include:
- develop
- release/*
- rapid/*
- Sprint/*
- Unity/*
Now, I have a bash script through which I want to add a string after this string; " - develop". Here's the point I want to maintain the spacing format.
Here;s my bash file code.
$target_string= " - develop"
$replacment_string=" - TerraformTest/*"
sed -i "/$target_string/a$replacment_string" test.txt
But the result I got it this:
trigger:
branches:
include:
- develop
- TerraformTest/*
- release/*
- rapid/*
- Sprint/*
- Unity/*
Is there any way, I can put tab in sed command to obtain the output like this:
trigger:
branches:
include:
- develop
- TerraformTest/*
- release/*
- rapid/*
- Sprint/*
- Unity/*

Answer 1

You could use a YAML-aware tool such as yq. This command inserts TerraformTest/* as the second element in the array at .trigger.branches.include:
yq '
.trigger.branches.include |=
([.[0], "TerraformTest/*", del(.[0])] | flatten)
' infile.yml

Answer 2

You can match match and grab space of search string in a capture group and use it in replacement:
sed -E 's~^([[:blank:]]*)- develop~&\n\1- TerraformTest/*~' file
trigger:
branches:
include:
- develop
- TerraformTest/*
- release/*
- rapid/*
- Sprint/*
- Unity/*
Or using variables:
target_string='- develop'
replacment_string='- TerraformTest/*'
sed -E "s~^([[:blank:]]*)$target_string~&\n\1$replacment_string~" file
trigger:
branches:
include:
- develop
- TerraformTest/*
- release/*
- rapid/*
- Sprint/*
- Unity/*
Breakup:
^: Start
([[:blank:]]*): Match 0 or more whitespaces in capture group #1
$target_string: Match string contained in $target_string
Replacement:
&: Place whole match back
\n: Place a line break
\1: Place spaces string on next line
$replacment_string: Place new replacement value
TO save changes inline use:
sed -i.bak -E "s~^([[:blank:]]*)$target_string~&\n\1$replacment_string~" file

Answer 3

With your shown samples only, please try following awk code. Written and tested in GNU awk.
awk -v RS= '
match($0,/^trigger:\n[[:space:]]+branches:\n[[:space:]]+include:\n[[:space:]]+- develop/){
print substr($0,RSTART,RLENGTH)"\n - TerraformTest/*" substr($0,RSTART+RLENGTH)
}
' Input_file

Answer 4

It is best practice to use a YAML aware tool such as yq, Perl, Python, etc.
Here is a Ruby:
ruby -r yaml -e 'y=YAML.load($<.read)
begin
a=y["trigger"]["branches"]["include"]
a.insert(a.find_index("develop")+1,"TerraformTest/*")
puts YAML.dump(y)
rescue
puts "Not Found"
end
' file
Prints:
---
trigger:
branches:
include:
- develop
- TerraformTest/*
- release/*
- rapid/*
- Sprint/*
- Unity/*

Answer 5

Using sed
$ sed -Ei.bak '/ +- develop/{p;s/[a-z]+/TerraformTest\/*/}' file
trigger:
branches:
include:
- develop
- TerraformTest/*
- release/*
- rapid/*
- Sprint/*
- Unity/*