Linux Magazine Special Editions Shell Handbook - 2019 Edition

Before the icons, menus, and wobbly windows of the modern Linux user environment, users managed and interacted with their systems from the command line. Many advanced users still prefer to work from the keyboard, and many will tell you that exploring the commandline environment is the best way to build a deeper understanding of Linux. The Linux Shell Handbook is a thorough primer on the Bourne Again Shell (Bash) environment found on most Linux systems. You’ll learn to navigate, manipulate text, work with regular expressions, and customize your Bash settings. We’ll show you shell utilities for configuring hardware, setting up users and groups, managing processes, and installing software – and we’ll even help you get started creating your own Bash scripts to automate recurring tasks. Keep the Linux Shell Handbook…

Many desktop users approach the command line as though armed with a magic spell. They have a command – complete with options – to type or paste to get the desired results, but they are unclear what else might be going on. This approach is understandable; however, if you take the time to understand something of the structure of the command line, you can increase control over your computing. By default, most Linux distributions run Bash (the Bourne Again Shell). Bash is a command-line interpreter – a program that runs macros and other utilities. These macros and utilities are the commands that you enter at the prompt. They include those built into Bash, such as cd, and many others that are external, including most of the commands that you run.…

GNU/ Linux treats everything as a file. For this reason, learning file management commands should be among your first priorities. These commands are easy to remember because their names are usually abbreviations of their actions – for example, mv for move and ls for list – but their options can take time to learn. Basically, file management commands fall into three categories: directory and file movement, navigation and editing, and compression. Commands in all three categories are typically more powerful (and potentially more dangerous) than their desktop equivalents, thanks mainly to file globbing, or the use of standard patterns to refer to multiple files. Moving and Editing Directories and Files The most basic command for moving directories and files is cp. Its structure is simple: cp <options> <filesourcefile> <target>. By…

When it comes to finding and identifying files on your system, you are spoiled for choice. Linux offers a variety of tools that can help you locate files and programs, including find, locate, whereis, and which. These tools are not particularly difficult in use, and mastering them can help you use your Linux system more efficiently. Finding Files with find The find tool lets you search for files by name or a part of the name. By default, find searches recursively, meaning it looks for files through the entire directory tree. At the very minimum, find requires two options: a path to the directory where the search should start and the name of the file to look for. The name of the file is specified with the -name switch. For…

Most computer systems have an assortment of tools for filtering and processing data. A virus scanner, a spam fighter, a web search engine, a spell checker – each is a filter that sifts though data to isolate the information you really need. Your shell provides a filter, too. For example, ls *.jpg lists only JPEG images. Because so much of Linux depends on interpreting and processing plain text files, an entire shorthand exists for creating filters. The shorthand is called regular expressions, or regex. A regex applied to text can find, dissect, and extract virtually any pattern you seek. Table 1 shows some common regex operators, which you can string together and use in combination to build arbitrarily complex filters. The origin of regex dates back some 60 years to…

The Linux command line provides hundreds of small utilities to read, write, parse, and analyze data. With just a few extra keystrokes, you can combine those utilities into innumerable impromptu applications. For example, imagine you must extract an actor’s lines. That is to say, given the text shown in Listing 1, you must produce That's what they call a sanity clause for Groucho. The grep command can find substrings, strings, and patterns in a text file. You can use grep to find all lines that begin with GROUCHO. Then you can use cut to divide the matching lines into pieces and combine the two commands with a pipe (|): The grep clause searches the file marx.txt for all occurrences of “Groucho” that appear at the beginning of a line (-E…