명령어 다치고 yarn dev 이렇게 치면요

yarn : 'yarn' 용어가 cmdlet, 함수, 스크립트 파일 또는 실행할 수 있는 프로그램 이름으로 인식되지&nbsp;
않습니다. 이름이 정확한지 확인하고 경로가 포함된 경우 경로가 올바른지 검증한 다음 다시 시도하십
시오.
위치 줄:1 문자:1
+ yarn dev
+ ~~~~
&nbsp; &nbsp; + CategoryInfo&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; : ObjectNotFound: (yarn:String) [], CommandNotFoundException
&nbsp; &nbsp; + FullyQualifiedErrorId : CommandNotFoundException

이렇게 오류가떠요

<span style="background-color: #ffffff; color: #212529; font-family: 'Noto Sans KR', -apple-system, system-ui, BlinkMacSystemFont, 'Apple SD Gothic Neo', 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif, Oxygen, Ubuntu, Cantarell, 'Fira Sans', 'Droid Sans', Helvetica; font-size: 24px; letter-spacing: -0.3px;">기본 프로그램 설치하기 강의에서
<span style="background-color: #ffffff; color: #212529; font-family: 'Noto Sans KR', -apple-system, system-ui, BlinkMacSystemFont, 'Apple SD Gothic Neo', 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif, Oxygen, Ubuntu, Cantarell, 'Fira Sans', 'Droid Sans', Helvetica; font-size: 24px; letter-spacing: -0.3px;">
<span style="color: #212529; font-family: Noto Sans KR, -apple-system, system-ui, BlinkMacSystemFont, Apple SD Gothic Neo, Segoe UI, Roboto, Helvetica Neue, Arial, sans-serif, Oxygen, Ubuntu, Cantarell, Fira Sans, Droid Sans, Helvetica;">헬로우월드 치면
<span style="color: #212529; font-family: Noto Sans KR, -apple-system, system-ui, BlinkMacSystemFont, Apple SD Gothic Neo, Segoe UI, Roboto, Helvetica Neue, Arial, sans-serif, Oxygen, Ubuntu, Cantarell, Fira Sans, Droid Sans, Helvetica;">
<span style="color: #212529; font-family: Noto Sans KR, -apple-system, system-ui, BlinkMacSystemFont, Apple SD Gothic Neo, Segoe UI, Roboto, Helvetica Neue, Arial, sans-serif, Oxygen, Ubuntu, Cantarell, Fira Sans, Droid Sans, Helvetica;">이렇게 안뜨네요
<span style="color: #212529; font-family: Noto Sans KR, -apple-system, system-ui, BlinkMacSystemFont, Apple SD Gothic Neo, Segoe UI, Roboto, Helvetica Neue, Arial, sans-serif, Oxygen, Ubuntu, Cantarell, Fira Sans, Droid Sans, Helvetica;">
<span style="color: #212529; font-family: Noto Sans KR, -apple-system, system-ui, BlinkMacSystemFont, Apple SD Gothic Neo, Segoe UI, Roboto, Helvetica Neue, Arial, sans-serif, Oxygen, Ubuntu, Cantarell, Fira Sans, Droid Sans, Helvetica;">웬만하면 페이지 다뜨는데요 다른강의에서도
<span style="color: #212529; font-family: Noto Sans KR, -apple-system, system-ui, BlinkMacSystemFont, Apple SD Gothic Neo, Segoe UI, Roboto, Helvetica Neue, Arial, sans-serif, Oxygen, Ubuntu, Cantarell, Fira Sans, Droid Sans, Helvetica;">
<span style="color: #212529; font-family: Noto Sans KR, -apple-system, system-ui, BlinkMacSystemFont, Apple SD Gothic Neo, Segoe UI, Roboto, Helvetica Neue, Arial, sans-serif, Oxygen, Ubuntu, Cantarell, Fira Sans, Droid Sans, Helvetica;">헬로우 월드 치면 페이지가 잘뜨는데요
<span style="color: #212529; font-family: Noto Sans KR, -apple-system, system-ui, BlinkMacSystemFont, Apple SD Gothic Neo, Segoe UI, Roboto, Helvetica Neue, Arial, sans-serif, Oxygen, Ubuntu, Cantarell, Fira Sans, Droid Sans, Helvetica;">
<span style="color: #212529; font-family: Noto Sans KR, -apple-system, system-ui, BlinkMacSystemFont, Apple SD Gothic Neo, Segoe UI, Roboto, Helvetica Neue, Arial, sans-serif, Oxygen, Ubuntu, Cantarell, Fira Sans, Droid Sans, Helvetica;">처음으로 잘안되네요
<span style="color: #212529; font-family: Noto Sans KR, -apple-system, system-ui, BlinkMacSystemFont, Apple SD Gothic Neo, Segoe UI, Roboto, Helvetica Neue, Arial, sans-serif, Oxygen, Ubuntu, Cantarell, Fira Sans, Droid Sans, Helvetica;"><img src="https://cdn.inflearn.com/public/comments/4aa1d464-3fe6-40ac-9d22-e3d1e054b966/제목 없음.png" title="제목 없음.png" width="1903" height="1070" alt="" />

yarn 이 설치되지 않으신 것 같습니다.
npm i -g yarn
해보세요!

인프런 커뮤니티 질문&답변

기본 프로그램 설치하기 강의에서 안되는게있서요