Add time in front of any shell command and once it finishes, it will show how long it took to run. This could be useful when making tweaks to your build system and want to know what impact it has on the running time.

For example time npm run build will show the following output:

real    1m15.659s
user    1m26.313s
sys     0m7.911s

See this Stack Overflow answer for more details about the difference between real, user and sys