macOS defaults to the Zsh shell, which reads configuration from ~/.zshrc. Legacy Bash setups rely on ~/.bash_profile or ~/.bashrc. To inspect existing hidden configuration files in your home directory, run:

ls -la ~

Focus on .zshrc for modern macOS versions. Editing this file allows persistent environment variable definitions across terminal sessions.

Open the configuration file using a terminal editor:

vim ~/.zshrc

Press i to enter insert mode before making changes.

To extend the executable search patth, prepend or append directories to the existing PATH variable. The colon (:) acts as the mandatory delimiter between directories:

export PATH="/opt/homebrew/opt/go@1.21/bin:$PATH"

This syntax retrieves the current PATH, attaches the new directory to the front, and reassigns the combined string. Swapping the order ($PATH:/new/dir) places the new directory at the end of the search sequence, which affects command priority.

Custom variables can be defined independently and referenced within other declarations:

export GO_ROOT="/usr/local/go"
export GO_BIN="$GO_ROOT/bin:$GO_ROOT/pkg/tool"

The $GO_ROOT syntax dynamically injects the previously assigned value, keeping configurations modular and easier to maintain.

After editing, press Esc, type :wq, and hit Enter to save and exit the editor.

Changes remain inactive until the shell reloads the profile. Apply updates immediately with:

source ~/.zshrc

Verify that variables are correct registered by querying the environment:

echo $GO_ROOT

The terminal should output the exact directory string assigned earlier.

For rapid additions without launching an editor, append directly to the profile and reload in a single sequence:

echo 'export RUST_BIN="$HOME/.cargo/bin:$PATH"' >> ~/.zshrc && source ~/.zshrc

If a syntax error occurs during PATH modification (such as omitting the colon separator), standard commands like ls or vim will fail. Restore basic functionality temporarily by resetting the search path to system defaults:

export PATH="/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin"

This assignment only affects the active terminal window. Once commands are functional again, reopen the configuration file, correct the missing delimiter, save, and reload the profile to permanently resolve the issue.