Language Selection

English French German Italian Portuguese Spanish

MiniTutor: Shell Colors and Cursor Positions

Filed under
Linux

You can use characters to modify texts and how they are displayed, and also for fun you can draw, create animations, statusbar, progressbar and more.

These commands can be called as escape sequencies because all they use ASCII's ESC (033). They must be send directly to the terminal and you can use 'print', 'printf' or 'echo'. The sequencies use ESC to definy colors and cursos position, they begin with an 'ESC' followed by a '[', and close with a 'm'. In the middle we must add numbers separeted by ';'.

First, we show how to use these commands and sequencies to change default colors displayed by shell. The command format is 'ESC[n1;n2;...m', it means, after the begin '033[' (ESC[) and before the end 'm', we have all numeric instructions. The default is '0' if any number are written, and those numbers indicate text color, background color and video atributes or codes. Those atributes can change text form and how the colors is going to be showed.

The list of text colors is: 30 (black/gray), 31 (red), 32 (green), 33 (brown/yellow), 34 (blue), 35 (purple), 36 (cyan) and 37 (gray/white). The list of background colors is: 40 (black/gray), 41 (red), 42 (green), 43 (brown/yellow), 44 (blue), 45 (purple), 46 (cyan) and 47 (gray/white). The atributes are: 0 (default), 1 (bold), 5 (blinking) and 7 (reverse background and color). There are some differences between colors above as you can see, for example 43 is used to display a brown color, but if you enable bold text the color turnes to yellow.

The number are read following this sequence: background, text color and atributes, for example '40,32,1,5' means black background, green color, bold text and blinking.

You must not forget to enable interpretation of backslash escapes, '-e' option, while using 'echo, for example: echo -e '\033[41m TESTING \033[m'.

Test example: echo -e '\033[40;33;1m Welcome to \033[40;31;1m GoblinX\033[40;33;1mNewsletter \033[m'.

Second, after learn how to change colors, we show how to change the text position. The command to set where display a text is 'ESC[. The common list is: ESC[nA (n lines up and same column), ESC[nB (n lines down, same column), ESC[nC (n columns to the right, same line), ESC[nD (n columns to the left, same line), ESC[nE (n lines down in column 1), ESC[nF (n lines up, column 1), ESC[nG (go to n column, current line) and ESC[n;mH (go to column m and line n).

An example: echo -e '\033c\033[4;7HSaturday\033[AMonday\033[2B\033[DWednesday'

In the above line, '\033c' cleans the screen, '\033[4;7HSaturday' writes Saturday at line 4 column 7, '\033[AMonday' moves the cursos up one line and writes Monday, '\033[2B' moves the cursor two lines down in the same column, and '\033[DWednesday' goes back one column in the same line and writes Wednesday.

There are also more commands to move the cursor before write a text and also others to clear texts and move the screen. The list is: ESC[nJ (n=0, clear until the end of the screen, n=1, clear until the begin of the screen, n=2, clear all screen) ESC[nK (n=0, clear until the end of the line, n=1, clear until the begin of the line, n=2, clear all line), ESC[nM (clear n lines below), ESC[nP (clear n characters in the right side), ESC[nX (clear n characters in the left side and write spaces instead), ESC[n@ (insert n blank spaces), ESC[nL (insert n blank lines), ESC[nS (move the screen n linhas up) and ESC[nT (move the screen n linhas down).

Test example: echo -e '\033c \033[40;33;1m Welcome to \033[4;7H \033[40;31;1m GoblinX\033[1C \033[40;33;1mNewsletter \033[m'

Another example, a counter:
for i in 1 2 3 4 5 6 7 8 9; do echo -ne "\033c \033[G\033[@Counted =\033[11G\033[0K$i"; sleep 1; done; echo

Your shell scripts can inform and also be funny, you just need to let your imagination flyes. This minitutor is heavly inspired by an article in the book 'Programação Shell Linux' written by Julio Cesar Neves.

Minitutor from: GoblinX Minitutors

More in Tux Machines

digiKam 7.7.0 is released

After three months of active maintenance and another bug triage, the digiKam team is proud to present version 7.7.0 of its open source digital photo manager. See below the list of most important features coming with this release. Read more

Dilution and Misuse of the "Linux" Brand

Samsung, Red Hat to Work on Linux Drivers for Future Tech

The metaverse is expected to uproot system design as we know it, and Samsung is one of many hardware vendors re-imagining data center infrastructure in preparation for a parallel 3D world. Samsung is working on new memory technologies that provide faster bandwidth inside hardware for data to travel between CPUs, storage and other computing resources. The company also announced it was partnering with Red Hat to ensure these technologies have Linux compatibility. Read more

today's howtos

  • How to install go1.19beta on Ubuntu 22.04 – NextGenTips

    In this tutorial, we are going to explore how to install go on Ubuntu 22.04 Golang is an open-source programming language that is easy to learn and use. It is built-in concurrency and has a robust standard library. It is reliable, builds fast, and efficient software that scales fast. Its concurrency mechanisms make it easy to write programs that get the most out of multicore and networked machines, while its novel-type systems enable flexible and modular program constructions. Go compiles quickly to machine code and has the convenience of garbage collection and the power of run-time reflection. In this guide, we are going to learn how to install golang 1.19beta on Ubuntu 22.04. Go 1.19beta1 is not yet released. There is so much work in progress with all the documentation.

  • molecule test: failed to connect to bus in systemd container - openQA bites

    Ansible Molecule is a project to help you test your ansible roles. I’m using molecule for automatically testing the ansible roles of geekoops.

  • How To Install MongoDB on AlmaLinux 9 - idroot

    In this tutorial, we will show you how to install MongoDB on AlmaLinux 9. For those of you who didn’t know, MongoDB is a high-performance, highly scalable document-oriented NoSQL database. Unlike in SQL databases where data is stored in rows and columns inside tables, in MongoDB, data is structured in JSON-like format inside records which are referred to as documents. The open-source attribute of MongoDB as a database software makes it an ideal candidate for almost any database-related project. This article assumes you have at least basic knowledge of Linux, know how to use the shell, and most importantly, you host your site on your own VPS. The installation is quite simple and assumes you are running in the root account, if not you may need to add ‘sudo‘ to the commands to get root privileges. I will show you the step-by-step installation of the MongoDB NoSQL database on AlmaLinux 9. You can follow the same instructions for CentOS and Rocky Linux.

  • An introduction (and how-to) to Plugin Loader for the Steam Deck. - Invidious
  • Self-host a Ghost Blog With Traefik

    Ghost is a very popular open-source content management system. Started as an alternative to WordPress and it went on to become an alternative to Substack by focusing on membership and newsletter. The creators of Ghost offer managed Pro hosting but it may not fit everyone's budget. Alternatively, you can self-host it on your own cloud servers. On Linux handbook, we already have a guide on deploying Ghost with Docker in a reverse proxy setup. Instead of Ngnix reverse proxy, you can also use another software called Traefik with Docker. It is a popular open-source cloud-native application proxy, API Gateway, Edge-router, and more. I use Traefik to secure my websites using an SSL certificate obtained from Let's Encrypt. Once deployed, Traefik can automatically manage your certificates and their renewals. In this tutorial, I'll share the necessary steps for deploying a Ghost blog with Docker and Traefik.