Bashrc

Bashrc, typically ~/.bashrc, is a shell script that Bash reads and executes for interactive non-login shells. It is used to customize the user’s environment and behavior of the shell. The file is located in the user's home directory and is often sourced by other startup files to ensure interactive features are available.

Purpose and contents: bashrc commonly defines aliases and functions, exports environment variables, adjusts the shell prompt (PS1), configures history behavior, enables or disables shell options (via shopt and set), and sets up programmable completion. It is also common to enable color output and to initialize features such as autocomplete or command shortcuts.

Loading and scope: Interactive login shells typically read system-wide and user-wide startup files, which may source ~/.bashrc so that interactive features persist. Non-login interactive shells read ~/.bashrc directly. On some systems, login shells do not read ~/.bashrc unless it is explicitly sourced from a login startup file (for example, ~/.bash_profile or ~/.profile). System-wide equivalents include /etc/bash.bashrc or /etc/bashrc, depending on the distribution.

Common patterns: a typical bashrc may define aliases (for example, ll='ls -la'), adjust PATH, set EDITOR, configure history preferences, enable color support, and source additional scripts such as bash_completion. Users may also define custom functions to streamline workflows.

Usage tips: after editing, apply changes with source ~/.bashrc or . ~/.bashrc. For portability across environments, keep bashrc focused on interactive behavior and avoid commands that depend on login-time context. Security considerations include avoiding exposure of sensitive data and ensuring proper permissions.