DEV Community

Carlos Leonel Ramirez
Carlos Leonel Ramirez

Posted on • Originally published at carloslramirez.com on

Linux Upskill Challenge: Day 5 - More or less…

#linux

Introduction

This is my journal note following the Linux Upskill Challenge: Day 5.

  • The more and less command
  • How Tabs completion works in Linux, what happe when there is ambiguity?
  • history command
  • repeat a command with !<line number> and how the command get at the begining of the queue, but the previous number get lost.
  • repeat a command - use of ctrl+r to search for any part of a previous command
  • hidde files are also called dot files because they start with a dot(.), you list them with ls -la or ls -ltra
  • The most common use of a “dot file” is to keep personal settings in the home directory
  • the use of less to look the contents of .bashrc, .bash_history
  • the use of nano to create a file with the summary of the last 4 lessons
  • Changing the bash terminal to zsh, fish and oh-my-zsh
  • Terminal multiplexers: screen and tmux
  • some simple examples of how to customize your tmux

📄 more and less commands

  • more is a command that lets you view text files one page at a time. You press space to go to the next page. When you get to the end of the file, you cannot go back.

  • less is similar but more powerful — you can scroll up and down with the arrow keys and search inside the file with /.

  • Example of use:

  more / etc/services
  less /etc/services
Enter fullscreen mode Exit fullscreen mode

I experimented with these two commands that allow you to view the content of text files. Certainly, they work in different ways. I think the winner is less, which is more flexible, but I think there should be situations where more does the work.

🧠 Tab Completion in Linux

  • Tab completion lets you press Tab to auto-complete commands, file names, or paths.
  • This is a feature provided by the shell: bash , zsh , and fish all supports Tab completion.
  • If there’s ambiguity (multiple matches), pressing Tab twice shows a list of possibilities.
  • Works with commands, paths, directories, users, etc.
  • Saves time and avoids typing errors.

I’m not good at memorizing commands, so this is definitely very useful when you’re working in the command line.

⏳ The history Command

  • The history command shows a list of previously run commands with line numbers. 
history
Enter fullscreen mode Exit fullscreen mode

history is a built-in shell command.

this only works well in bash shell

  • Here’s a clever trick to navigate the history output: 
history | less
Enter fullscreen mode Exit fullscreen mode
  • This uses a pipe (|) to pass the output of history as input to the less command.

It’s a great example of the UNIX philosophy: “using small tools that work together by chaining them”.

🔁 Repeating Commands

  • You can repeat a command from history using !<line-number>, for example: 
!102
Enter fullscreen mode Exit fullscreen mode

When you re-run a command with !number, it moves to the end of the history queue with a new number, and the original number is overwritten.

  • You can also rerun the last command with: 
!!
Enter fullscreen mode Exit fullscreen mode
  • Let said you submit a command that requieres to sudo but you forgot, instead of submit the command again preceding sudo you can use sudo !!, like this example: 
less /etc/shadow
/etc/shadow: Permission denied
sudo !!
sudo less /etc/shadow
Enter fullscreen mode Exit fullscreen mode

🔍 Search Command History with Ctrl + r

  • Press Ctrl + r to start a reverse search through your history.
  • Start typing part of a command, and it will autocomplete the most recent match.
  • Press Ctrl + r again to go further back, or Enter to run it.

🕵️ Hidden Files (Dot Files)

  • Hidden files in Linux start with a dot (.), so they’re often called dot files.
  • You list them with: 
ls -la
Enter fullscreen mode Exit fullscreen mode
  • Or: 
ls -ltra
Enter fullscreen mode Exit fullscreen mode
  • Common dot files include .bashrc, .bash_profile, .bash_history,.ssh/, etc.
  • These files store personal configurations in your home directory.

📂 Exploring Dot Files

  • I used less to read the contents of dot files: 
less ~/.bashrc
less ~/.bash_history
Enter fullscreen mode Exit fullscreen mode

✏️ Editing with nano

  • nano is one of the most widely used text editors in Linux because of its ease of use
  • I used nano to create a new file with a summary of the first 4 lessons.
  • Example: 
nano lessons_summary.txt
Enter fullscreen mode Exit fullscreen mode

nano|450

I was already familiar with the basic functions of nano, but I will have to delve into more advanced functions later.

🐚 Switching Shells: bash, zsh, fish

  • Linux supports multiple shell programs beyond just bash.

  • I tried out:

  • I wrote this as a separate note to describe the process to install and change the shell

🧩 Terminal Multiplexers: screen and tmux

A terminal multiplexer is a command-line tool that lets you run and manage multiple terminal sessions within a single terminal window or SSH connection, and keep them running even if you disconnect.

screen

  • screen is a tool that let you have multiple shell sessions on a server, and let them “in the background”, while you work in another thing.
  • You can even logout for your server, and get back when you left on a session.

I confess it was hard to get it the first time, but after watching a YouTube video and asking ChatGPT, I kind of got it. I’ll put the references at the end of the note.

tmux

20250523T0650-tmux-basic-guide

Top comments (0)