Not understanding when to use ~/.bashrc, /etc/profile ,~/.bash_profile or ~/.profile?

[polaryeti]

I've read tidbits of pages from around 10 books, and I can safely say I am even more confused than before. Earlier I'd just set everything in .bashrc file. LOL.

Say I've scenarios like these:

1) I want to set system variables for user "jacky", what should I use?

2) I want to set system variables for all users, what  should I use?

3) I want to set alias for user "jacky", what should I use?

4) I want to set alias for all users, what should I use?

What are interactive/non-interactive login/non-login shells?

I've asked chatgpt but it gave me convoluted reply.  So, it was not very clear.

[requinix]

1/2. What do you mean by "system variable"?
3/4. What do you mean by "alias"?
5. Interactive means you can do stuff, non-interactive means you can't do stuff, and non-login means you can't even log in. Is there something specific about those terms that you think you're missing?

[gizmola]

You won't get one answer because

• conventions vary by linux distribution
• can vary by shell
  • bourne shell tends to be a base
    • System scripts do things at boot time and runlevel changes
    • bash is a backwards compatible with sh, but has many extra features
      • Config works with sh/bash/ksh/csh, but anything you do should be bourne shell syntax
    • Other shells have become popular, and are even the default on newer os's (as in OSX now defaulting to zsh)
      • If you're using a newer shell like zsh or fish, then they typically have their own config files you need to research

 

Long story short:

• Read the /etc/profile script and the /etc/bashrc script.  Often one or both will include scripts in a directory like /etc/profile.d
  • If that is already working, you should place scripts that customize things for all users in that directory rather than modifying the /etc/profile or /etc/bashrc script directly.
• Individual settings should be done in the user's home directory
  • use ~/.profile or ~/.bashrc
• Aliases are not part of the bourne shell, so you are utilizing a shell specific extension
  • Bash often supports other files like ~/.bash_aliases

 

As for types of shells:

• Login shell facilitates login, and will run commands in the files mentioned previously
• An interactive shell is connected to a tty so that the user can interact with it.  It will also have certain default settings like job control enabled
• A non-interactive shell is used for scripts, since the user will not be interacting

 

This old serverfault thread provides a good summary of the configuration files loaded.