yq
v4.x
v4.x
  • yq
  • How It Works
  • Recipes
  • Upgrading from V3
  • Commands
    • Evaluate
    • Evaluate All
    • Shell Completion
  • Operators
    • Add
    • Alternative (Default value)
    • Anchor and Alias Operators
    • Array to Map
    • Assign (Update)
    • Boolean Operators
    • Collect into Array
    • Column
    • Comment Operators
    • Compare Operators
    • Contains
    • Create, Collect into Object
    • Date Time
    • Delete
    • Divide
    • Document Index
    • Encode / Decode
    • Entries
    • Env Variable Operators
    • Equals
    • Eval
    • File Operators
    • Filter Operator
    • Flatten
    • Group By
    • Has
    • Keys
    • Kind
    • Length
    • Line
    • Load
    • Min
    • Map
    • Max
    • Modulo
    • Multiply (Merge)
    • Omit
    • Parent
    • Path
    • Pick
    • Pipe
    • Pivot
    • Recursive Descent (Glob)
    • Reduce
    • Reverse
    • Select
    • Shuffle
    • Slice Array
    • Sort
    • Sort Keys
    • Split into Documents
    • String Operators
    • Style
    • Subtract
    • Tag
    • To Number
    • Traverse (Read)
    • Union
    • Unique
    • Variable Operators
    • With
  • Usage
    • Output format
    • Working with CSV, TSV
    • Working with JSON
    • Working with Properties
    • Working with XML
    • Working with LUA
    • Working with TOML
    • Working with Shell Output
    • Front Matter
    • Split into multiple files
    • GitHub Action
    • Tips, Tricks, Troubleshooting
  • Github Page
Powered by GitBook
On this page
  • plain form: =
  • relative form: |=
  • Set line comment
  • Set line comment of a maps/arrays
  • Use update assign to perform relative updates
  • Where is the comment - map key example
  • Retrieve comment - map key example
  • Where is the comment - array example
  • Retrieve comment - array example
  • Set head comment
  • Set head comment of a map entry
  • Set foot comment, using an expression
  • Remove comment
  • Remove (strip) all comments
  • Get line comment
  • Get head comment
  • Head comment with document split
  • Get foot comment

Was this helpful?

  1. Operators

Comment Operators

Use these comment operators to set or retrieve comments. Note that line comments on maps/arrays are actually set on the key node as opposed to the value (map/array). See below for examples.

Like the = and |= assign operators, the same syntax applies when updating comments:

plain form: =

This will set the LHS nodes' comments equal to the expression on the RHS. The RHS is run against the matching nodes in the pipeline

relative form: |=

This is similar to the plain form, but it evaluates the RHS with each matching LHS node as context. This is useful if you want to set the comments as a relative expression of the node, for instance its value or path.

Set line comment

Set the comment on the key node for more reliability (see below).

Given a sample.yml file of:

a: cat

then

yq '.a line_comment="single"' sample.yml

will output

a: cat # single

Set line comment of a maps/arrays

For maps and arrays, you need to set the line comment on the key node. This will also work for scalars.

Given a sample.yml file of:

a:
  b: things

then

yq '(.a | key) line_comment="single"' sample.yml

will output

a: # single
  b: things

Use update assign to perform relative updates

Given a sample.yml file of:

a: cat
b: dog

then

yq '.. line_comment |= .' sample.yml

will output

a: cat # cat
b: dog # dog

Where is the comment - map key example

The underlying yaml parser can assign comments in a document to surprising nodes. Use an expression like this to find where you comment is. 'p' indicates the path, 'isKey' is if the node is a map key (as opposed to a map value). From this, you can see the 'hello-world-comment' is actually on the 'hello' key

Given a sample.yml file of:

hello: # hello-world-comment
  message: world

then

yq '[... | {"p": path | join("."), "isKey": is_key, "hc": headComment, "lc": lineComment, "fc": footComment}]' sample.yml

will output

- p: ""
  isKey: false
  hc: ""
  lc: ""
  fc: ""
- p: hello
  isKey: true
  hc: ""
  lc: hello-world-comment
  fc: ""
- p: hello
  isKey: false
  hc: ""
  lc: ""
  fc: ""
- p: hello.message
  isKey: true
  hc: ""
  lc: ""
  fc: ""
- p: hello.message
  isKey: false
  hc: ""
  lc: ""
  fc: ""

Retrieve comment - map key example

From the previous example, we know that the comment is on the 'hello' key as a lineComment

Given a sample.yml file of:

hello: # hello-world-comment
  message: world

then

yq '.hello | key | line_comment' sample.yml

will output

hello-world-comment

Where is the comment - array example

The underlying yaml parser can assign comments in a document to surprising nodes. Use an expression like this to find where you comment is. 'p' indicates the path, 'isKey' is if the node is a map key (as opposed to a map value). From this, you can see the 'under-name-comment' is actually on the first child

Given a sample.yml file of:

name:
  # under-name-comment
  - first-array-child

then

yq '[... | {"p": path | join("."), "isKey": is_key, "hc": headComment, "lc": lineComment, "fc": footComment}]' sample.yml

will output

- p: ""
  isKey: false
  hc: ""
  lc: ""
  fc: ""
- p: name
  isKey: true
  hc: ""
  lc: ""
  fc: ""
- p: name
  isKey: false
  hc: ""
  lc: ""
  fc: ""
- p: name.0
  isKey: false
  hc: under-name-comment
  lc: ""
  fc: ""

Retrieve comment - array example

From the previous example, we know that the comment is on the first child as a headComment

Given a sample.yml file of:

name:
  # under-name-comment
  - first-array-child

then

yq '.name[0] | headComment' sample.yml

will output

under-name-comment

Set head comment

Given a sample.yml file of:

a: cat

then

yq '. head_comment="single"' sample.yml

will output

# single
a: cat

Set head comment of a map entry

Given a sample.yml file of:

f: foo
a:
  b: cat

then

yq '(.a | key) head_comment="single"' sample.yml

will output

f: foo
# single
a:
  b: cat

Set foot comment, using an expression

Given a sample.yml file of:

a: cat

then

yq '. foot_comment=.a' sample.yml

will output

a: cat
# cat

Remove comment

Given a sample.yml file of:

a: cat # comment
b: dog # leave this

then

yq '.a line_comment=""' sample.yml

will output

a: cat
b: dog # leave this

Remove (strip) all comments

Note the use of ... to ensure key nodes are included.

Given a sample.yml file of:

# hi

a: cat # comment
# great
b: # key comment

then

yq '... comments=""' sample.yml

will output

a: cat
b:

Get line comment

Given a sample.yml file of:

# welcome!

a: cat # meow
# have a great day

then

yq '.a | line_comment' sample.yml

will output

meow

Get head comment

Given a sample.yml file of:

# welcome!

a: cat # meow

# have a great day

then

yq '. | head_comment' sample.yml

will output

welcome!

Head comment with document split

Given a sample.yml file of:

# welcome!
---
# bob
a: cat # meow

# have a great day

then

yq 'head_comment' sample.yml

will output

welcome!
bob

Get foot comment

Given a sample.yml file of:

# welcome!

a: cat # meow

# have a great day
# no really

then

yq '. | foot_comment' sample.yml

will output

have a great day
no really
PreviousColumnNextCompare Operators

Last updated 1 year ago

Was this helpful?