Profile files are hidden files (starting with a dot) in Linux/RHEL that define your shell environment. They control settings like environment variables, aliases (shortcuts for commands), and terminal behavior. These files are processed in a specific order when you log in or open a terminal window.

Types of Profile Files

1. system-wide profiles

2. user-specific profiles.

System-wide Profiles (/etc directory):

• /etc/profile: This file contains system-wide environment variables and settings that apply to all users. It's executed when a user logs in.

  

• /etc/inputrc: This file defines keyboard mappings and shortcuts for the readline library, which is used by Bash for command-line editing.

  

• /etc/bashrc: This file contains system-wide Bash configurations and functions that are applied to all users when they start a new Bash shell.

  

User Profiles ($HOME directory):

• .bash_profile (or .profile for non-bash shells): Executed for login shells (when you first log in through a terminal). It sets permanent environment variables and aliases.

• .bashrc: Executed for all interactive shells (including login shells and subsequent terminal windows). It sets aliases and customizations that you want in all interactive shells.

Create Own Alias

1. Open a text editor (e.g., nano ~/.profile.d/my_alias.sh) and add the following line, replacing command with the actual command you want to shorten and alias_name with your preferred alias:

alias alias_name='command'

2. Save the file and source it using the following command (replace my_alias.sh with your filename if different):

source ~/.profile.d/my_alias.sh

3. Now, whenever you type alias_name, the actual command will be executed.

Loading in Home Directory Bash Files:

1. When you log in or open a terminal:

   • /etc/profile (if not modified)

   • /etc/profile.d scripts (alphabetical order)

   • ~/.bash_profile (or ~/.profile)

2. For subsequent interactive shells:

   • ~/.bashrc

Impact Based on Shell:

Different shells have different profile files. For example, Bash uses .bash_profile and .bashrc, while other shells like Zsh may use .zshrc. Customizations made in these files will only affect the behavior of the respective shell.

/etc/skel Directory:

This directory contains skeleton files used to create new user home directories. When a new user is added, files from /etc/skel are copied to the user's home directory. This ensures consistency in user environments. Common files found in /etc/skel include:

• .bash_logout (executed when logging out)

• .bash_profile (or .profile)

• .bashrc