blog: Add 2025-07-22.md

Author: ingydotnet

blog/2025-07-22.md

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+---
+title: ys and yq
+date: 2025-07-22
+draft: false
+authors: [ingydotnet]
+categories: [Summer-of-YS]
+edit: blog/2025-07-22.md
+comments: true
+---
+
+Today I met [Mike Farah](https://github.com/mikefarah), the creator of
+[yq](https://github.com/mikefarah/yq)!
+
+I help maintain the [go-yaml](https://github.com/yaml/go-yaml) YAML framework
+for Go, and am working with Mike to help it fix certain issues in yq.
+
+It looks like a promising future for both go-yaml and yq.
+
+It turns out that YS has a lot of crossovers with yq.
+
+Let's take a closer look at how they compare.
+
+<!-- more -->
+
+
+## What is yq?
+
+yq is a command-line tool for querying and manipulating YAML (and other) data.
+
+It is meant to work much like [jq](https://stedolan.github.io/jq/) for JSON.
+
+I've used yq a lot, and it's a great tool.
+It can do a few things that YS can't do.
+(At least, not yet!)
+
+
+## Quick Usage Guide
+
+Let's look at the examples in [yq's Quick Usage Guide](
+https://github.com/mikefarah/yq?tab=readme-ov-file#quick-usage-guide) and
+compare them to YS.
+
+Let's imagine we have the following `file.yaml` file:
+
+```yaml
+a:
+  b:
+  - c: hello # A greeting
+```
+
+### Read a value
+
+yq:
+
+```bash
+$ yq '.a.b[0].c' file.yaml
+hello
+```
+
+YS:
+
+```bash
+$ ys '.a.b.0.c' file.yaml
+hello
+```
+
+
+### Pipe from STDIN
+
+yq:
+
+```bash
+$ yq '.a.b[0].c' < file.yaml
+hello
+```
+
+YS:
+
+```bash
+$ ys '.a.b.0.c' < file.yaml
+hello
+```
+
+
+## Update a yaml file
+
+This is where yq really shines!
+It can update YAML and preserve the original formatting and comments!
+
+yq:
+
+```bash
+$ yq '.a.b[0].c = "cool"' file.yaml
+a:
+  b:
+    - c: cool # A greeting
+```
+
+Well, the `- c:` line got re-indented, but the comment is still there.
+
+ys can't preserve comments but it can update the value.
+Not as nicely though.
+
+YS:
+
+```bash
+$ ys -Ye '.assoc-in(["a" "b" 0 "c"] "cool")' file.yaml
+a:
+  b:
+  - c: cool
+```
+
+
+### Update using environment variables
+
+yq:
+
+```bash
+$ yq '.a.b[0].c = strenv(USER)' file.yaml
+a:
+  b:
+    - c: ingy # A greeting
+```
+
+YS:
+
+```bash
+$ ys -Ye '.assoc-in(["a" "b" 0 "c"] ENV.USER)' file.yaml
+a:
+  b:
+  - c: ingy
+```
+
+
+### Merge multiple files
+
+Let's imagine we have the following `file2.yaml` file:
+
+```yaml
+x:
+  y:
+    z: foobar # A comment
+```
+
+yq:
+
+```bash
+$ yq -n 'load("file.yaml") * load("file2.yaml")'
+a:
+  b:
+    - c: hello # A greeting
+x:
+  y:
+    z: foobar # A comment
+```
+
+YS:
+
+```bash
+$ ys -Ye 'load("file.yaml") + load("file2.yaml")'
+a:
+  b:
+  - c: hello
+x:
+  y:
+    z: foobar
+
+```
+
+
+### Convert JSON to YAML
+
+Let's imagine we have the following `file.json` file:
+
+```json
+{
+  "a": "b",
+  "c": "d"
+}
+```
+
+
+yq:
+
+```bash
+$ yq -Poy file.json
+a: b
+c: d
+```
+
+YS:
+
+```bash
+$ ys -Y file.json
+a: b
+c: d
+```
+
+
+## Conclusion
+
+I wish I had more time today to compare ys and yq more deeply.
+
+You can see that at a certain level they both have a lot in common.
+
+I'd encourage you to use both of them.
+
+They are certainly complementary!