Configure defaults for Bash, Zsh, or PowerShell

April 13, 2026

The default shell for operating systems is typically:

Linux: Bash
macOS: Zsh
Windows: PowerShell

Each shell vendor has configuration files to change the default shell parameters. Here are some useful examples:

Remove duplicate entries in shell history

To remove duplicate entries in shell history for pressing “up” on repeated commands to give the last non-duplicated command, set for the respective shell as follows.

Bash: “~/.bashrc”: ignore duplicate lines, and omits lines that start with space.

export HISTCONTROL=ignoredups:ignorespace

Zsh: “~/.zshrc”

setopt hist_ignore_dups
setopt hist_ignore_space

PowerShell: “$profile”: set the history to ignore duplicates.

Set-PSReadlineOption -HistoryNoDuplicates