GitBook: [#206] deep update example

commands/evaluate.md

@@ -0,0 +1,54 @@
+---
+description: >-
+  Evaluates the given expression against each yaml document in each file, in
+  sequence
+---
+
+# Evaluate
+
+## Usage: 
+
+```bash
+yq eval [expression] [yaml_file1]... [flags]
+```
+
+Aliases: `eval, e`
+
+Note that you can pass in `-` as a filename to pipe from STDIN.
+
+## Examples:
+
+```bash
+# runs the expression against each file, in series
+yq e '.a.b | length' f1.yml f2.yml 
+
+# '-' will pipe from STDIN
+cat file.yml | yq e '.a.b' f1.yml -  f2.yml
+
+# prints out the file
+yq e sample.yaml 
+cat sample.yml | yq e
+
+# prints a new yaml document
+yq e -n '.a.b.c = "cat"' 
+
+# updates file.yaml directly
+yq e '.a.b = "cool"' -i file.yaml 
+```
+
+
+
+## Flags:
+
+```
+  -h, --help          help for eval
+  -C, --colors        force print with colors
+  -e, --exit-status   set exit status if there are no matches or null or false is returned
+  -I, --indent int    sets indent level for output (default 2)
+  -i, --inplace       update the yaml file inplace of first yaml file given.
+  -M, --no-colors     force print with no colors
+  -N, --no-doc        Don't print document separators (---)
+  -n, --null-input    Don't read input, simply evaluate the expression given. Useful for creating yaml docs from scratch.
+  -j, --tojson        output as json. Set indent to 0 to print json in one line.
+  -v, --verbose       verbose mode
+```