Use these comment operators to set or retrieve comments.
Like the `=` and `|=` assign operators, the same syntax applies when updating comments:
### plain form: `=`
This will assign the LHS nodes comments to the expression on the RHS. The RHS is run against the matching nodes in the pipeline
### relative form: `|=`
Similar to the plain form, however the RHS evaluates against each matching LHS node! 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
Given a sample.yml file of:
```yaml
a: cat
```
then
```bash
yq eval '.a lineComment="single"' sample.yml
```
will output
```yaml
a: cat # single
```
## Use update assign to perform relative updates
Given a sample.yml file of:
```yaml
a: cat
b: dog
```
then
```bash
yq eval '.. lineComment |= .' sample.yml
```
will output
```yaml
a: cat # cat
b: dog # dog
```
## Set head comment
Given a sample.yml file of:
```yaml
a: cat
```
then
```bash
yq eval '. headComment="single"' sample.yml
```
will output
```yaml
# single
a: cat
```
## Set foot comment, using an expression
Given a sample.yml file of:
```yaml
a: cat
```
then
```bash
yq eval '. footComment=.a' sample.yml
```
will output
```yaml
a: cat
# cat
```
## Remove comment
Given a sample.yml file of:
```yaml
a: cat # comment
b: dog # leave this
```
then
```bash
yq eval '.a lineComment=""' sample.yml
```
will output
```yaml
a: cat
b: dog # leave this
```
## Remove (strip) all comments
Note the use of `...` to ensure key nodes are included.
