Skip to content

zarf tools yq eval

zarf tools yq eval

(default) Apply the expression to each document in each yaml file in sequence


yq is a portable command-line data file processor ( See for detailed documentation and examples.

Evaluate Sequence

This command iterates over each yaml document from each given file, applies the expression and prints the result in sequence.

zarf tools yq eval [expression] [yaml_file1]... [flags]


# Reads field under the given path for each file
zarf tools yq e '.a.b' f1.yml f2.yml
# Prints out the file
zarf tools yq e sample.yaml
# Pipe from STDIN
## use '-' as a filename to pipe from STDIN
cat file2.yml | zarf tools yq e '.a.b' file1.yml - file3.yml
# Creates a new yaml document
## Note that editing an empty file does not work.
zarf tools yq e -n '.a.b.c = "cat"'
# Update a file in place
zarf tools yq e '.a.b = "cool"' -i file.yaml


-h, --help help for eval

Options inherited from parent commands

-C, --colors force print with colors
--csv-auto-parse parse CSV YAML/JSON values (default true)
--csv-separator char CSV Separator character (default ,)
-e, --exit-status set exit status if there are no matches or null or false is returned
--expression string forcibly set the expression argument. Useful when yq argument detection thinks your expression is a file.
--from-file string Load expression from specified file.
-f, --front-matter string (extract|process) first input as yaml front-matter. Extract will pull out the yaml content, process will run the expression against the yaml content, leaving the remaining data intact
--header-preprocess Slurp any header comments and separators before processing expression. (default true)
-I, --indent int sets indent level for output (default 2)
-i, --inplace update the file in place of first file given.
-p, --input-format string [auto|a|yaml|y|json|j|props|p|csv|c|tsv|t|xml|x|base64|uri|toml|lua|l] parse format for input. (default "auto")
--lua-globals output keys as top-level global variables
--lua-prefix string prefix (default "return ")
--lua-suffix string suffix (default ";\n")
--lua-unquoted output unquoted string keys (e.g. {foo="bar"})
-M, --no-colors force print with no colors
-N, --no-doc Don't print document separators (---)
-0, --nul-output Use NUL char to separate values. If unwrap scalar is also set, fail if unwrapped scalar contains NUL char.
-n, --null-input Don't read input, simply evaluate the expression given. Useful for creating docs from scratch.
-o, --output-format string [auto|a|yaml|y|json|j|props|p|csv|c|tsv|t|xml|x|base64|uri|toml|shell|s|lua|l] output format type. (default "auto")
-P, --prettyPrint pretty print, shorthand for '... style = ""'
--properties-array-brackets use [x] in array paths (e.g. for SpringBoot)
--properties-separator string separator to use between keys and values (default " = ")
-s, --split-exp string print each result (or doc) into a file named (exp). [exp] argument must return a string. You can use $index in the expression as the result counter.
--split-exp-file string Use a file to specify the split-exp expression.
--string-interpolation Toggles strings interpolation of \(exp) (default true)
--tsv-auto-parse parse TSV YAML/JSON values (default true)
-r, --unwrapScalar unwrap scalar, print the value with no quotes, colors or comments. Defaults to true for yaml (default true)
-v, --verbose verbose mode
--xml-attribute-prefix string prefix for xml attributes (default "+@")
--xml-content-name string name for xml content (if no attribute name is present). (default "+content")
--xml-directive-name string name for xml directives (e.g. <!DOCTYPE thing cat>) (default "+directive")
--xml-keep-namespace enables keeping namespace after parsing attributes (default true)
--xml-proc-inst-prefix string prefix for xml processing instructions (e.g. <?xml version="1"?>) (default "+p_")
--xml-raw-token enables using RawToken method instead Token. Commonly disables namespace translations. See for details. (default true)
--xml-skip-directives skip over directives (e.g. <!DOCTYPE thing cat>)
--xml-skip-proc-inst skip over process instructions (e.g. <?xml version="1"?>)
--xml-strict-mode enables strict parsing of XML. See for more details.


  • zarf tools yq - yq is a lightweight and portable command-line data file processor.