website_rasmus/content/post/script-to-add-a-page-level-variable-to-content-front-matter-in-hugo.md

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---
title: "Script to add a page-level variable to content front matter in hugo"
date: 2018-10-10T12:43:20-05:00
publishdate: 2018-10-10
lastmod: 2018-10-11
draft: false
tags: ["hugo", "command-line", "awk"]
---
This was originally a question posed on the [hugo discussion forums](https://discourse.gohugo.io/t/set-frontmatter-params-in-list-template/14645).
The user wanted to loop through all her content files and add a `weight` page-level variable to the front matter. The value of `weight` needed to be the first 2 characters of the content filename, since her content was named like `01_content.md`, `02_content.md`, etc.
She then wanted to `range` through her pages by their weight, like so:
```go
{{ range .Pages.ByWeight }}
<!-- some code -->
{{ end }}
```
## The script
```bash
#!/bin/bash
for file in *.md; do
weight=${file:0:2}
awk -v weight=$weight '/---/{
count++
if(count == 2){
sub("---","weight: " weight "\n---",$0)
}
}
{print}' $file > tmp && mv tmp $file
done
```
## Explained
Loop through all files in the directory with extension `.md`:
```bash
for file in *.md; do
# ...
done
```
Set a variable using the first 2 characters of the filename:
```bash
weight=${file:0:2}
```
Call an `awk` program and pass it a `weight` variable:
```bash
awk -v weight=$weight
```
When the `awk` program encounters the 2nd occurrence of `---` (which is how you end front matter in YAML), it inserts the `weight` page-level variable on the line above:
```bash
'/---/{
count++
if(count == 2){
sub("---","weight: " weight "\n---",$0)
}
}
{print}'
```
Redirect the output of the `awk` program to a tmp file, then overwrite the original content file with the tmp file:
```bash
> tmp && mv tmp $file
```
## Result
Original `01_content.md`:
```yml
---
title: "Some title"
draft: false
---
```
Updated `01_content.md`:
```yml
---
title: "Some title"
draft: false
weight: 01
---
```