When you are experimenting, you will likely find it helpful to consult the documentation for various commands. (2) Try consulting documentation for unknown commands If you think something probably works a certain way, test out your expectations! Except where noted otherwise, the examples in this book do not require any special privileges or permissions, and do not require any software aside from Bash itself and very common utilities that are generally found on any system where Bash is. You may want to try out some of the examples but more important is to try things out that aren't just copied from the book. You will probably find this book most useful if you have a Bash command-line open in another window while you are going through it. How To Read (1) It's ideal to practice Bash while reading On Android, an app called Termux can be installed. If you have Cygwin, just make sure that the directory containing those utilities - likely something like C:\Cygwin\bin - is listed in your Windows path. If you are on an older machine and don't have SSH access to a GNU/Linux or Unix system, you will probably find it easiest to make use of this book if you are using something like Cygwin, which has not only Bash but also many other common utilities, than if you are using a Bash port for Windows that includes only Bash. If you are on a Windows 10 or Windows 11 system, you can install Windows Subsystem for Linux. If you are using a Unix-like operating system like FreeBSD or MacOS and Bash shell is not installed as default, you can install Bash from their package manager or use their default shell which have Bash support. It is recommended that you use a GNU/Linux based distribution like Ubuntu, Manjaro, etc. You will need to have Bash installed on your system. They are particularly suited to all of these because they allow complexity without requiring it: if a script just needs to run two external programs, then it can be a two-line script, and if it needs all the power and decision-making ability of a Turing-complete imperative programming language, then it can have that as well. They are also commonly used as installation scripts for complex programs. Shell scripts are commonly used for many system administration tasks, such as performing disk backups, evaluating system logs, and so on. One script might be set to run when the system boots up another might be set to run every weekday at 2:30 AM another might run whenever a user logs into the system. Shell scripts can be called from the interactive command-line described above, or they can be called from other parts of the system. Shell scripting is the art of creating and maintaining such scripts. In effect, a Bash shell script is a computer program written in the Bash programming language. A script might contain just a very simple list of commands - or even just a single command - or it might contain functions, loops, conditional constructs, and all the other hallmarks of imperative programming. In addition to the interactive mode, where the user types one command at a time, with immediate execution and feedback, Bash (like many other shells) also has the ability to run an entire script of commands, known as a "Bash shell script" (or "Bash script" or "shell script" or just "script"). It was intended as a free software alternative to the Bourne shell (in fact, its name is an acronym for Bourne Again SHell), and it incorporates all features of that shell, as well as new features such as integer arithmetic and job control. It was created in the late 1980s by a programmer named Brian Fox with the request of Richard Stallman, working for the Free Software Foundation. It is widely available, being the default shell on many GNU/Linux distributions and formerly on Mac OSX, with ports existing for many other systems. Wikipedia has related information at Bash (Unix shell)īash is a "Unix shell": a command line interface for interacting with the operating system.
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