23 posts tagged with "linux"

A few weeks ago, I've posted a SSH - Launch a terminal on your session without having to authenticate yourself article about the ssh command in Linux.

I'm pretty sure, like me, you are tired to use command line like ssh christophe@1.2.3.4 to start a ssh connection because ... you know, you don't need to connect on a server; no, you need to connect to the server where the application is running; you know the name of the MyAmazingApp application but certainly not the name of the server or its IP.

That's the case for me anyway.

So, I need to connect to my vault, in which I list all the information about applications, server names, credentials to be used, ...

It would be pretty cool to run ssh MyAmazingApp no?

Over the last few weeks, I've been working on a Python script that generates PDFs. My script had to generate 70,000 of them and that obviously takes a while.

My idea was to have my script run in a Linux console and, in a second console, with a counter that increases with the number of files that have been created on the hard disk.

The first script will be in Python and I wanted something ultra-simple and using a simple Linux command.

The command ls folder_name | wc -l works but didn't stay running. Let's see how we can do better with inotifywait.

After my article SSH - Launch a terminal on your session without having to authenticate yourself, it was obvious that, next to the ssh and scp commands, I forgot the sftp one.

In this article, we'll explore how to start a SFTP connection to a remote server; from the command line.

In the second section, we'll also learn how to configure the sftp connection to use a proxy server.

Imagine that you regularly need to connect to your Linux server: you need to launch a tool such as Putty, you need to enter your login, password, etc. and carry out various operations before you can access the terminal.

If your password isn't saved in Putty's configuration, you'll have to launch another tool like a password vault; in short, it's annoying.

In this article, we'll look at how to authenticate once and for all on the server using an SSH key.

For me, one of the undeniable strengths of the command line under Linux is the management of the history of previously executed commands.

To be able to press the Up or Down keys on the keyboard to return to previously run commands, wow.

For older users, there was DOSKEY under MSDos, but Linux goes much further.

Let's look at a few tricks.

In my previous article; Linux - Take advantage of the number of CPUs you have; start concurrent jobs, we've seen how to start jobs in parallel.

The next cool thing is to show a progression bar in your console. This has a number of advantages, including a clear view of what's been done and what's still to be done, as well as an attractive interface.

Months ago, I've found this french blog post in my RSS feeds: https://xieme-art.org/post/bash-avance-barre-de-progression/ and, just, wow!!!

Let's play with it.

In my professional activity, I've been faced with the following requirement: process each line of a CSV file and make a POST API call to upload a document.

One line of the CSV contained information that needed to be communicated to an API service, and each line corresponded to a PDF file. So if there are 1000 lines in the CSV file, I have to make 1000 API calls to upload 1000 PDFs.

I wrote my script in Linux Bash and then it was time to optimise: not just one API call at a time, but as many as possible.

Let's how we can start more than one task at a time using Linux Bash.

When writing Bash scripts, I'm always putting some description block in front of any functions like I do in any language (think to PHP Docblock).

With PHP, there are a few tools like phpDocumentor for extracting these blocks and generate documentation but do such tools exist for Bash? I don't know, I haven't found any.

So I've written a small Bash script to accomplish this i.e. parse any .sh file present in a folder, extract doc blocks and create one markdown document for any retrieved script. Each function's documentation will then be copied in Markdown, then a table of contents will be appended and, finally, a generic readme.md file will display the list of markdown files retrieved.

Still faced with the problem of having to compare two versions of the same script (see the article Linux - Comparing two folders/files in the console), this time we're going to consider that the file we need to compare is a Bash script and that we have two versions of it.

And that we may have made the two files evolve in different ways, i.e. that one or other, or even both, of the files may have been modified.

The aim is therefore to compare the versions and highlight the differences.

In a previous article, we've seen a simple CLI command to display the list of functions present in a script but what about a Bash script that will scan an entire folder; retrieve any .sh scripts and check if functions are sorted in the files?