Ubuntu: correct way to add to PATH after installation of new software, .profile vs .bashrc vs /etc/profile

I downloaded and install the tar.gz file as noted here in the documentation: https://golang.org/doc/install

Edited my .profile to include these lines

export PATH=$PATH:/usr/local/go/bin
export GOPATH=$HOME/go
export PATH=$PATH:$GOPATH/bin

The first line is from the documentation and the second and third lines are in the book Learn Go by O'Reilly.

My book wanted me to install the hey library for load testing websites. This was right after the section on installing Go.

(base) n@u-IdeaPad-3-15IIL05: hey https://www.golang.org

Command 'hey' not found, but can be installed with:

sudo snap install hey       # version 0.1.2, or
sudo snap install hey-mail  # version 1.2.0
sudo apt  install hey       # version 0.1.2-2

See 'snap info <snapname>' for additional versions.

(base) n@u-IdeaPad-3-15IIL05:/media/n/NTFSUbuWin/Projects/Golang$ source $HOME/.profile(base) n@u-IdeaPad-3-15IIL05:/media/n/NTFSUbuWin/Projects/Golang$ hey https://www.golang.org

Summary:
  Total:        1.5133 secs
  Slowest:      0.6518 secs
  Fastest:      0.1353 secs
  Average:      0.3005 secs
  Requests/sec: 132.1624
  

Response time histogram:
  0.135 [1]     |■
  0.187 [61]    |■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
  0.239 [21]    |■■■■■■■■■■■■■■
  0.290 [40]    |■■■■■■■■■■■■■■■■■■■■■■■■■■
  0.342 [23]    |■■■■■■■■■■■■■■■
  0.394 [11]    |■■■■■■■
  0.445 [7]     |■■■■■
  0.497 [7]     |■■■■■
  0.548 [1]     |■
  0.600 [5]     |■■■
  0.652 [23]    |■■■■■■■■■■■■■■■


Latency distribution:
  10% in 0.1462 secs
  25% in 0.1637 secs
  50% in 0.2594 secs
  75% in 0.3852 secs
  90% in 0.6205 secs
  95% in 0.6376 secs
  99% in 0.6415 secs

Details (average, fastest, slowest):
  DNS+dialup:   0.0134 secs, 0.1353 secs, 0.6518 secs
  DNS-lookup:   0.0003 secs, 0.0000 secs, 0.0043 secs
  req write:    0.0000 secs, 0.0000 secs, 0.0006 secs
  resp wait:    0.1255 secs, 0.0650 secs, 0.3958 secs
  resp read:    0.0031 secs, 0.0002 secs, 0.0213 secs

Status code distribution:
  [200] 200 responses

So it worked after I did source $HOME/.profile from the project directory although I already ran this command in a different terminal instance I thought globally.

What is the problem?

It comes down to the fact ~/.profile is sourced at login, while ~/.bashrc is sourced whenever you open a new terminal. So if you add the go environment variables to ~/.profile, the variables will not be sourced until you logout then login again.

The golang documentation recommends to use ~/.profile because it is the recommended place for environment variables.

Also please note that neither ~/.bashrc nor ~/.profile are system-wide. Other users don't have access them. System-wide environment variables could be set in /etc/profile.

Please refer to this great explanation about differences between .bashrc and .profile for more details.

Contrary to whatever I read on documentation about writing exports to .profile to make them system-wide, there was a comment until the author deleted it saying write it to whichever shell I am using.
So on Ubuntu 20.04, I am writing my exports to .bashrc instead.