Linux

Linux Shells: Detailed Comparison

Core Shell Types

Shell Release Key Features Configuration File POSIX Compliant
Bash 1989 Default shell, scripting focus, history ~/.bashrc Yes
Zsh 1990 Advanced completion, themes, plugins ~/.zshrc Partial
Fish 2005 User-friendly syntax, web-based config ~/.config/fish No
Ksh 1983 Advanced scripting, fast execution ~/.kshrc Yes
Tcsh 1978 C-like syntax, command-line editing ~/.tcshrc No
Dash 1997 Minimalist, fast startup (default /bin/sh) ~/.dashrc Yes

Key Technical Differences

  1. Scripting Capabilities

    • Bash/Ksh: Advanced control structures, arrays, regex
    • Dash: Strict POSIX compliance (limited features)
    • Fish: Modern syntax but incompatible with POSIX

  2. Performance

    • Startup Time: Dash > Bash > Zsh
    • Script Execution: Ksh/Dash > Bash > Zsh

  3. Interactive Features

    # Zsh example: advanced globbing
ls **/*.txt(N)  # List all txt files including subdirs

# Fish example: inline documentation
grep --help | fish -c 'help grep'

  4. Customization

    • Zsh: Oh-My-Zsh framework (200+ plugins)
    • Fish: Web-based configuration GUI
    • Bash: Requires manual customization (~/.bashrc)

When to Use Which

  • System Scripts: Bash/Dash (POSIX compliance)
  • Interactive Use: Zsh/Fish (developer-friendly)
  • Legacy Systems: Ksh/Tcsh (older UNIX compatibility)
  • Embedded Systems: Dash/Almquist (low resource usage)

Compatibility Matrix

Feature Bash Zsh Fish Ksh
POSIX Scripts ✓ ✗ ✗ ✓
Array Support ✓ ✓ ✓ ✓
Associative Arrays 4.0+ ✓ ✗ ✗
Plugin Ecosystem Basic Rich Rich None