YQ edit files with multiple document in place

Question

I have a YAML file with 2 documents

# template.yaml

a : 1
---
b : 2

I'm trying to edit the YAML file inplace. I've tried using

# yq4

yq -i '
    select(documentIndex == 0) | 
    .a = 3 |
    select(documentIndex == 1) |
    .b = 4
' template.yaml

But figured out that this outputs an empty file. I figured that the output of select(documentIndex == 0) | .a = 3 is a single document, which when piped to select(documentIndex == 1), results in an empty document.

In yq3, I can do this by writing

#yq3

yq w -d1 .a 3 | yq w -d2 .b 4` > template.yaml

Is there an equivalent to this yq4 command in yq3?

score 3 · Accepted Answer · answered Nov 21 '22 at 09:51

3

You have it right, on why it doesn't work with mikefarah/yq v4. A simpler way to do that would be to do

yq 'select(di == 0).a  = 3  | select(di == 1).b = 5'  yaml

It is not recommended to use the in-place substitution flag, before verifying the contents of the stdout. Always add it afterwards.

answered Nov 21 '22 at 09:51

Inian

80,270
14
142
161

Thanks for the answer! I think this should be added into the example – Anugerah Erlaut Nov 21 '22 at 10:05

score 1 · Answer 2 · answered Nov 21 '22 at 10:09

I figured out another way to do a more roundabout way to do it.

We can split and then merge the files together

yq 'select(documentIndex == 0)  | .a = 3' > doc_0.yaml
yq 'select(documentIndex == 1)  | .b = 4' > doc_0.yaml

yq eval-all '. as $item' doc_0.yaml doc_1.yaml > $output.yaml

It turns out that the differnt files are read and written out as documents.

YQ edit files with multiple document in place

2 Answers2