Bash is a Unix shell and command language written by Brian Fox for the GNU Project as a free software replacement for the Bourne shell. Bash is a command processor that typically runs in a text window, where the user types commands that cause actions. Bash can also read and execute commands from a file, called a shell script.

bash

Extracting meaningful data from strings is a crucial skill when working with bash, and bash gives us powerful tools to do so: `head`, `tail`, `cut`, `sed`, and `awk`. But these tools can be hard to understand without spending time to learn them, so many developers fall into a rut of blindly copying and pasting commands. No more! With this mini-course, you'll understand the basic ins and outs of these commands in under 15 minutes. 


Head and tail are handy tools for getting just the beginning or end of a text stream. In this lesson, we’ll look at getting the first or last lines from the beginning or end of text. 

Use head and tail to Get the Start or End of Text in Bash

sed, which stands for stream editor, is probably most commonly used to replace text patterns with a new one, which is exactly what we’ll learn in this lesson. 

You'll learn how what flags you pass, the address argument as well as the commands that sed takes. The sed syntax can be summarized like this: `sed [flags] '[address]command[options]' [input file]`

Find and Replace Text with Sed in Bash

In this lesson, you'll learn how sed can be used to delete lines of text. You can use a regex or line numbers to target a line for deletion. This makes a sed a powerful tool for automatically performing lots of tedious text deletions for you. 

Delete Lines of Text with sed in Bash

In this lesson, you'll learn how sed can be used to insert lines of text. We'll use sed's `i` command to insert a header at the top of every .js file in a directory. 

Insert Text with sed in Bash

`cut` makes it quick and easy to break a string into parts based on a delimiter or get a substring. In practice, it’s somewhat similar to JavaScript’s `String.split` method. In this video, we’ll look at using `cut` to work with semver strings and truncate a long string.

Split a String into Parts with `cut` in Bash

`awk` is a specialized tool and programming language for querying and transforming text.   In this lesson, we’ll scratch the surface of the possibilities it provides by leveraging it in one of its most common use cases: extracting data from columns of text. Awk makes it easy to select and print just the columns and rows that we want from commands, like `ps`, that return a table of data.

Extract Data From Columns of Text with awk in Bash

In this lesson, we'll use the power of awk to select the columns and rows of data that match our condition. We'll pass a `,` (comma) to the `-F` flag (the F stands for field separator), to tell awk to split on commas. From there, the world is our oyster and we can tell awk to only return rows that match whatever parameters we pass.

Manipulating strings in bash

Cameron Nokes

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