yq/pkg/yqlib/doc/String Operators.md

String Operators

RegEx

This uses golangs native regex functions under the hood - See https://github.com/google/re2/wiki/Syntax for the supported syntax.

Join strings

Given a sample.yml file of:

- cat
- meow
- 1
- null
- true

then

yq eval 'join("; ")' sample.yml

will output

cat; meow; 1; ; true

Match string

Given a sample.yml file of:

foo bar foo

then

yq eval 'match("foo")' sample.yml

will output

string: foo
offset: 0
length: 3
captures: []

Match string, case insensitive

Given a sample.yml file of:

foo bar FOO

then

yq eval '[match("(?i)foo"; "g")]' sample.yml

will output

- string: foo
  offset: 0
  length: 3
  captures: []
- string: FOO
  offset: 8
  length: 3
  captures: []

Match with capture groups

Given a sample.yml file of:

abc abc

then

yq eval '[match("(abc)+"; "g")]' sample.yml

will output

- string: abc
  offset: 0
  length: 3
  captures:
    - string: abc
      offset: 0
      length: 3
- string: abc
  offset: 4
  length: 3
  captures:
    - string: abc
      offset: 4
      length: 3

Match with named capture groups

Given a sample.yml file of:

foo bar foo foo  foo

then

yq eval '[match("foo (?P<bar123>bar)? foo"; "g")]' sample.yml

will output

- string: foo bar foo
  offset: 0
  length: 11
  captures:
    - string: bar
      offset: 4
      length: 3
      name: bar123
- string: foo  foo
  offset: 12
  length: 8
  captures:
    - string: null
      offset: -1
      length: 0
      name: bar123

Capture named groups into a map

Given a sample.yml file of:

xyzzy-14

then

yq eval 'capture("(?P<a>[a-z]+)-(?P<n>[0-9]+)")' sample.yml

will output

a: xyzzy
n: "14"

Match without global flag

Given a sample.yml file of:

cat cat

then

yq eval 'match("cat")' sample.yml

will output

string: cat
offset: 0
length: 3
captures: []

Match with global flag

Given a sample.yml file of:

cat cat

then

yq eval '[match("cat"; "g")]' sample.yml

will output

- string: cat
  offset: 0
  length: 3
  captures: []
- string: cat
  offset: 4
  length: 3
  captures: []

Test using regex

Like jq'q equivalant, this works like match but only returns true/false instead of full match details

Given a sample.yml file of:

- cat
- dog

then

yq eval '.[] | test("at")' sample.yml

will output

true
false

Substitute / Replace string

This uses golang regex, described here Note the use of |= to run in context of the current string value.

Given a sample.yml file of:

a: dogs are great

then

yq eval '.a |= sub("dogs", "cats")' sample.yml

will output

a: cats are great

Substitute / Replace string with regex

This uses golang regex, described here Note the use of |= to run in context of the current string value.

Given a sample.yml file of:

a: cat
b: heat

then

yq eval '.[] |= sub("(a)", "${1}r")' sample.yml

will output

a: cart
b: heart

Split strings

Given a sample.yml file of:

cat; meow; 1; ; true

then

yq eval 'split("; ")' sample.yml

will output

- cat
- meow
- "1"
- ""
- "true"

Split strings one match

Given a sample.yml file of:

word

then

yq eval 'split("; ")' sample.yml

will output

- word