.bashrc and .bash_profile in Linux CLI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the .bashrc file in Linux?

The .bashrc file runs commands and sets environment variables for interactive non-login shells, like when you open a new terminal window.

beginner

When is the .bash_profile file executed?

The .bash_profile file runs commands and sets environment variables for login shells, such as when you log in to your Linux system via console or SSH.

intermediate

How can you make sure your .bashrc settings are applied when you log in?

You can add the line source ~/.bashrc inside your .bash_profile so that the .bashrc file runs during login shells too.

beginner

What is the difference between a login shell and a non-login shell?

A login shell starts when you log in to your system (console, SSH). A non-login shell starts when you open a new terminal window inside your desktop session.

beginner

Why might you put aliases and functions in .bashrc instead of .bash_profile?

Because aliases and functions are mainly used in interactive shells, putting them in .bashrc ensures they are available every time you open a terminal window.

Which file is executed when you log in to a Linux system via SSH?

A .bashrc

B .bash_logout

C .bash_profile

D .profile

The .bash_profile file runs for login shells like SSH sessions.

If you open a new terminal window in your desktop environment, which file is usually executed?

A .bash_logout

B .bashrc

C .bash_profile

D .bash_history

New terminal windows usually start non-login shells that run .bashrc.

How can you ensure that .bashrc runs during login shells?

A Add source ~/.bash_profile in .bashrc

B Rename .bashrc to .bash_profile

C Delete .bash_profile

D Add source ~/.bashrc in .bash_profile

Adding source ~/.bashrc inside .bash_profile runs .bashrc during login shells.

Which file is best for setting environment variables that should apply to all shell sessions?

A .bash_profile

B .bash_logout

C .bashrc

D .bash_history

Environment variables for login shells are best set in .bash_profile.

What type of shell is started when you log in to your system?

A Login shell

B Non-login shell

C Interactive shell

D Background shell

A login shell starts when you log in to your system.

Explain the roles of .bashrc and .bash_profile in managing your shell environment.

Think about when you open a terminal vs when you log in.

Describe how you would set up your shell so that aliases work both when you log in and when you open a new terminal window.

Remember which file runs in login and non-login shells.

Practice

1. What is the primary purpose of the .bash_profile file in Linux?

easy

A. It stores command history for the shell.

B. It runs every time a new terminal window opens to set aliases.

C. It runs once at login to set environment variables.

D. It manages system-wide user permissions.

Solution

1. Step 1: Understand the role of .bash_profile

   The .bash_profile file is executed once when a user logs in to the system. It is used to set environment variables and run commands that should only happen once per login session.

2. Step 2: Differentiate from .bashrc

   The .bashrc file runs every time a new terminal is opened, mainly for setting aliases and shell options, not environment variables at login.

3. Final Answer:

   It runs once at login to set environment variables. -> Option C

4. Quick Check:

   .bash_profile = runs once at login [OK]

Hint: Remember: .bash_profile runs once at login [OK]

Common Mistakes:

• Confusing .bash_profile with .bashrc
• Thinking .bash_profile runs for every new terminal
• Assuming .bash_profile manages command history

2. Which of the following is the correct way to load .bashrc from .bash_profile?

easy

A. execute ~/.bashrc

B. load ~/.bashrc

C. run ~/.bashrc

D. source ~/.bashrc

Solution

1. Step 1: Identify the command to run another script

   In bash, the source command runs commands from a file in the current shell environment.

2. Step 2: Confirm syntax for loading .bashrc

   Using source ~/.bashrc inside .bash_profile loads .bashrc settings for login shells.

3. Final Answer:

   source ~/.bashrc -> Option D

4. Quick Check:

   Use source to load scripts [OK]

Hint: Use 'source' to run .bashrc inside .bash_profile [OK]

Common Mistakes:

• Using non-existent commands like load or run
• Trying to execute .bashrc as a separate process
• Forgetting to use the tilde (~) for home directory

3. Given the following .bash_profile content:

export PATH="$PATH:/custom/bin"
source ~/.bashrc

And .bashrc contains:

alias ll='ls -l'

What happens when you open a new terminal after login?

medium

A. The alias ll is set but PATH does not include /custom/bin.

B. The PATH includes /custom/bin and alias ll is available.

C. The PATH is unchanged and alias ll is not available.

D. Only the PATH is updated; alias ll is not set.

Solution

1. Step 1: Understand .bash_profile execution at login

   The .bash_profile runs once at login, setting PATH to include /custom/bin and then sourcing .bashrc.

2. Step 2: Understand .bashrc execution on new terminals

   Since .bashrc is sourced by .bash_profile, the alias ll='ls -l' is set for the shell session.

3. Final Answer:

   The PATH includes /custom/bin and alias ll is available. -> Option B

4. Quick Check:

   .bash_profile sets PATH + sources .bashrc = alias set [OK]

Hint: Sourcing .bashrc in .bash_profile applies aliases at login [OK]

Common Mistakes:

• Assuming alias is not set without opening a new terminal
• Thinking PATH changes only after logout/login
• Ignoring that .bashrc is sourced inside .bash_profile

4. You added source ~/.bashrc to your .bash_profile, but aliases from .bashrc are still not available after login. What is the most likely problem?

medium

A. You forgot to log out and log back in after editing .bash_profile.

B. The .bashrc file has incorrect permissions and cannot be read.

C. The source command is misspelled in .bash_profile.

D. Aliases must be defined in .bash_profile, not .bashrc.

Solution

1. Step 1: Check if changes require re-login

   Changes to .bash_profile only take effect after a new login session, so you must log out and back in.

2. Step 2: Verify other options

   Incorrect permissions would cause errors, misspelling source would cause errors, and aliases are correctly placed in .bashrc.

3. Final Answer:

   You forgot to log out and log back in after editing .bash_profile. -> Option A

4. Quick Check:

   Changes in .bash_profile need re-login [OK]

Hint: Log out and back in to apply .bash_profile changes [OK]

Common Mistakes:

• Not logging out after editing .bash_profile
• Assuming aliases must be in .bash_profile
• Ignoring file permission issues

5. You want to ensure that environment variables set in .bash_profile and aliases in .bashrc are available in all interactive shells, including login and non-login shells. Which is the best approach?

hard

A. Add environment variables to .bash_profile and add source ~/.bashrc inside .bash_profile only.

B. Add source ~/.bashrc inside .bash_profile and add source ~/.bash_profile inside .bashrc.

C. Add source ~/.bashrc inside .bash_profile and add environment variables to .bashrc.

D. Add all environment variables and aliases only in .bashrc.

Solution

1. Step 1: Understand login vs non-login shells

   .bash_profile runs for login shells; .bashrc runs for interactive non-login shells.

2. Step 2: Best practice to share settings

   Put environment variables in .bash_profile and source .bashrc from .bash_profile to load aliases for login shells. Non-login shells read .bashrc directly.

3. Step 3: Avoid circular sourcing

   Do not source .bash_profile from .bashrc to prevent loops.

4. Final Answer:

   Add environment variables to .bash_profile and add source ~/.bashrc inside .bash_profile only. -> Option A

5. Quick Check:

   Env vars in .bash_profile + source .bashrc there = all shells get settings [OK]

Hint: Source .bashrc from .bash_profile; keep env vars in .bash_profile [OK]

Common Mistakes:

• Sourcing .bash_profile inside .bashrc causing loops
• Putting environment variables only in .bashrc
• Not sourcing .bashrc in .bash_profile