Using Shell executor some command not found

Hi

We use shell executor and then npm install -g gitbook-cli on the computer which giltab-runner installed, so we can use the gitbook command in shell

Then run pipeline, the job log

Running with gitlab-ci-multi-runner 9.1.0 (0118d89)
  on fish (8097b9ea)
Using Shell executor...
Running on vm...
Fetching changes...
HEAD is now at da3160b 添加gitlab-ci脚本
Checking out da3160b9 as master...
Skipping Git submodules setup
$ gitbook build . guide
bash: line 41: gitbook: command not found
ERROR: Job failed: exit status 1

gitbook command not found

Thanks for any help