DEV Community: Luis Gomez

Learning Terminal (Notes) Day #4 [Standard output]

Luis Gomez — Sun, 13 Mar 2022 22:09:35 +0000

Standard output

I just learned something very cool! You can save the command result just typing > name_archive.txt next to the command, ok this is not work for every command but works with the commands that provide a text output.

Example: If you want a list of your directories and save what do you have in just type ls directory_name > file_name.txt (I've just learned how to specific code here too ^^)

This command overwrite the text file every time you use it (if use the same file name) if you want to add text but no overwrite use the operator >> instead of >

Here let you more information about all of this

Pipe operator |

Pipe operator allows you run a command that his standard out put change as standard input to another command and this allow us to make another features.

echo: Generate an standard output from anything we type in terminal

Example: echo "Hello World"

With standard out put we can save the command's result to a file text but with pipe we can get that result and give it to another command like cat to visualize the result in out console command without save it.

Example: ls -lh | less

And if we want to save the result in another file like before but after seeing it with less we just to have add another pipe operator but with command tee.

Example: ls -lh | tee output.txt | less
(Like this generate the file first and then visualize it with less)

We can add filters too like sorting filter

Example: ls -lh | sort | tee output.txt | less

Learning Terminal (Notes) Day #3

Luis Gomez — Fri, 11 Mar 2022 21:00:10 +0000

Exploring Our File's Content

Commands

head: Show us the first ten lines of any text file, if you want to see more than 10 lines you can use the parameter -n followed by the name of lines that you want.
tail: Like head show us a chunk of the text file but with the difference that show us the last 10 lines and you can use the parameter -n too.
less: Less show us the file in a interactive way by console, in this kind of view you can type / and type words that you want to find. Like a searching engine.
xdg-open: This command open a file with your Text Editor by Default

What is a command?

A command can be 4 things:

1- An Executable Program
2- An Shell's Utility
3- A Shell's function
4- An Alias

type: Describe us the type of command that you give, just type the command next to the command type. Example: type ls.
alias: With this we can create an alias for a specific command and make easy the task that we want to do Example: l="ls -lh" this gonna show a directory in list AND with a human lecture.

WARNING: Alias are temporary, when you close the terminal and run a new one the alias is gonna disappear
help: Brings you information about how to use and works a command. Example: help cd.
man: Brings you an manual about command that you want to know. Example: man cd.
info: Works like man but with an different interface.
whatis: Show information about command but with less details.

Wildcards

Wildcards in summary is an advanced search using ls command.

How to use: Type the command and the special parameters that you want to get.

Example

To search for txt files

ls *.txt
The asterisk means all (I've seen that use asterisk to mean to all in computer science) and next you type the kind of file that you want.

There are a lot of functions with wildcards more information here.
There are too many uses for wildcards and depend your needs so I just gonna let the basics for now.

Learning Terminal (Notes) Day #2

Luis Gomez — Wed, 09 Mar 2022 16:43:27 +0000

Handle Files & Directories

There are a few parameters that can be useful with command ls

ls:
- S: This modifier give us the list of files and directories ordered by Size
- r: Sort the list in reverse

-Tree: Show our whole directories as tree structure

-L: The L parameter show our tree with the number of levels that we specify

mkdir: with this command we can create a new directory or commonly called a folder just we have to type the name after the command and if you want that the folder's name have spaces you have to type between quotation marks.
touch: Create a new file

We can create as much files and directories as we want at once just typing the name of the folders or files after the previous one.

cp: Command copy as you can imagine this command allow us to copy files just type the name of the file to copy and the name that you want the copy have also you can specify the directory where you want to copy save.
mv: It works like copy but moving the files
rm: WARNING Take care of this command you can broke your whole Operative System, you can delete files with this command and you can delete directories with parameter -r (recursive). If you type the paremeter -ir you can review and decide if you want to delete the files.

Learning Terminal (Notes)

Luis Gomez — Tue, 08 Mar 2022 16:55:29 +0000

So the terminal, That scary place that no one wants to see.
Take it easy is not that bad as seems. It's just different.

What is the terminal?
An terminal is an user graphical interface where you can give specific orders to the computer probably you have seen it in a lot of movies and series about hackers.

It looks like this:

The terminal is just the interface(a window) inside can run a shell where we can type and execute the commands, there are different types of shells such as:

Bournshell
Bash Shell
Z Shell (The most popular and included in macbooks from 2019)
C Shell
Korn Shell
Fish Shell
PowerShell (For windows)

So the firs thing that we have to know is how to browse in our file system, you know the window with folders, files and all our stuff in a computer but in the terminal.

The file system works as a tree branching out, and you can navigate with commands. More information by freecodecamp

Basic commands:

ls: show the files in our directory
- We can add modifiers to our commands like -l this modifier or parameter is for show our directory more detailed and as a list
- -h is for a human lecture h for human (more legible)
cd: (change directory) no needed more description right?

This command need a parameter this parameter is the directory that we want to go so forward the command we have to write the directory wished.

Example: cd /Downloads

clear: clean our screen shortcut: ctrl + l or command + l
cd: if you type just cd this command gonna send you to your home directory.
cd: .. if you type two dots after cd that gonna return a directory back
pwd: Print Working Directory
file: This one describe a file. You have to type the name of the file after the command file with his extension.

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