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* Remove extra backtick * Reword explanation of update * Reword explanation of relative update * Change "remaple" to "remain" * Change "clovver" to "clobber" * Reword explanation of update for comment operators * Reword explanation of relative update for comment operators * Change "array" to "expression" * Change "the golangs" to "Golang's" * Change "golangs" to "Golang's" * Change "can durations" to "can add durations" * Change "array scalars" to "arrays" * Change "beit" to "be it" * Fix typo in `eval` tip * Fix typo in header for `has` operation * Add space before pipe in `line` operator example * Fix typos in explanation of deep array merges * Change "is now used" to "is now used." * Change "object," to "object." * Changes "indexes" to "indices" * Remove extraneous copied text from `..` article * Reword explanation of `...` operator * Change "your are" to "you are" * Add link to `string` operator docs in `select` article * Change "is a" to "parameter specifies" in `string` operators article * Change "new line" to "newline" * Change "golang regex" to "Golang's regex" * Change "golang" to "Golang" * Add period * Remove comma in `subtract` article * Remove duplicate number subtraction example * Remove comma in `traverse` operator article * Clarify use of brackets when `read`ing with special characters
951 B
951 B
Eval
Use eval to dynamically process an expression - for instance from an environment variable.
eval takes a single argument, and evaluates that as a yq expression. Any valid expression can be used, be it a path .a.b.c | select(. == "cat"), or an update .a.b.c = "gogo".
Tip: This can be a useful way to parameterise complex scripts.
Dynamically evaluate a path
Given a sample.yml file of:
pathExp: .a.b[] | select(.name == "cat")
a:
b:
- name: dog
- name: cat
then
yq 'eval(.pathExp)' sample.yml
will output
name: cat
Dynamically update a path from an environment variable
The env variable can be any valid yq expression.
Given a sample.yml file of:
a:
b:
- name: dog
- name: cat
then
pathEnv=".a.b[0].name" valueEnv="moo" yq 'eval(strenv(pathEnv)) = strenv(valueEnv)' sample.yml
will output
a:
b:
- name: moo
- name: cat