Command not executing after installation Ubuntu 18.04

Question

• I'm using ubuntu 18.04 machine. I'm facing some issues from last few days. After installing some programs, commands aren't executing. Before some days, i had installed nodemon with npm. After installation i just execute nodemon and it says Command 'nodemon' not found, did you mean... I tried restarting terminal and them my machine. Tried installing it globally and with sudo too.
• It happened again with me just now. With commands ngx and firebase.

What to do with this. Please comment if you need additional info.

Answer 1

Finally find the solution. It was npm issues. i won't giving me any error but just won't working says command not found. So it fixed by reconfiguring npm directory. Here is ref. https://docs.npmjs.com/resolving-eacces-permissions-errors-when-installing-packages-globally