A shell is a special user program that provides an interface for the user to use operating system services. Shell accepts human-readable commands from users and converts them into something which the kernel can understand. It is a command language interpreter that executes commands read from input devices such as keyboards or from files. The shell gets started when the user logs in or starts the terminal.
BASH (Bourne Again Shell): It is the most widely used shell in Linux systems. It is used as default login shell in Linux systems and in macOS. It can also be installed on Windows OS.
A program which is responsible for providing an interface to a user so that he/she can access the shell. It basically allows users to enter commands and see the output of those commands in a text-based interface. Large scripts that are written to automate and perform complex tasks are executed in the terminal.
A shell script is a file containing a series of commands for the shell to execute. The shell itself is a command-line interpreter (CLI), while a shell script is a saved list of instructions (usually with .sh extension) like myscript.sh.
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Automate Repetitive Tasks Shell scripts turn routine jobs like file cleanup, backups, or server updates into one-click actions, saving time and reducing manual effort
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Reliable and Consistent Shell scripts run the exact same steps every time, without mistakes. Once you write and test a script, you can count on it to perform tasks consistently whether it's setting up servers, cleaning up files, or running a deployment. This removes human error and ensures predictable results.
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Native Support on Unix/Linux Systems Shell scripting is natively supported on Unix-based systems, requiring no additional installations. The shell environment (like Bash or Zsh) is pre-installed, allowing scripts to run seamlessly across most Linux distributions and Unix-like operating systems.
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Great for Linking Commands to Work Together Shell scripts make it easy to link different commands together. You can pass the output of one command into another, filter data, or run tasks step by step all in one script. This helps automate complex jobs using simple building blocks.
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Ideal for IT, DevOps & Monitoring Shell scripts help automate important tasks like checking system health, setting up servers, and scheduling jobs to run at specific times (using tools like cron). In DevOps, they are widely used to speed up deployments and manage infrastructure without doing everything manually.
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Lightweight and Easy to Write They are interpreted, so there is no compile step. You can write a useful script in minutes, and test it instantly perfect for quick fixes and small tasks.