The most popular shell for unix till date is:
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Bourne
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Bash
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C shell
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Korn shell
Bash (Bourne Again SHell) is the most widely used Unix shell today, serving as the default shell on most Linux distributions and macOS. It combines compatibility with the Bourne shell and features from C shell and Korn shell, making it the de facto standard for system administration and scripting.
Bash (the Bourne Again SHell) became the default shell on most Linux distributions and is bundled with macOS (historically) and countless Unix-like systems, making it the most widely used shell in practice today. Older shells like the original Bourne shell, C shell, and Korn shell are still used in some environments but have far smaller install bases and community adoption than Bash.