linux-unix

recent posts related to linux and unix

Notes about setting up HTTPS on websites using LetEncrypt and certbot

As a note to self, I added SSL/TLS certificates to a couple of websites using LetEncrypt. Here are a couple of notes about the process:

A large collection of Unix/Linux ‘grep’ command examples

Linux grep commands FAQ: Can you share some Linux/Unix grep command examples?

Sure. The name grep means "general regular expression parser", but you can think of the grep command as a "search" command for Unix and Linux systems: it's used to search for text strings and more-complicated "regular expressions" within one or more files.

I think it's easiest to learn how to use the grep command by showing examples, so let's dive right in.

How to tell grep to ignore special characters in a string (solution)

Back in the old days I thought that any pattern that was including in single-quotes with the Unix grep command meant that the pattern inside the string was completely ignored by grep. But these days I have to escape special characters with a backslash character, which is really annoying. This example shows what I mean:

The Red Hat ethos

The URL contains a statement of the Red Hat ethos. A couple of good quotes:

Open source is a development model, not a business model. Red Hat is in the enterprise software business and is a leading provider to the Global 500. Enterprise customers need products, not projects and it’s incumbent on vendors to know the difference. Open source projects are hotbeds of innovation and thrive on constant change. These projects are where sometimes constant change happens, where the development is done.

How to easily determine the blocksize of a filesystem

I just saw that this is a way you can easily determine the blocksize of a filesystem, at least a Mac/Unix/Linux filesystem:

$ echo foo > foo

$ du -h foo
4.0K    foo

I tried to do the same thing with touch foo, but that didn’t work. Without digging into it more, the key seems to be in having very little text in the file, at which point the du command shows the minimum block size for the file.

A big collection of Unix/Linux ‘find’ command examples

Linux/Unix FAQ: Can you share some Linux find command examples?

Sure. The Unix/Linux find command is very powerful. It can search the entire filesystem to find files and directories according to the search criteria you specify. Besides using the find command to locate files, you can also execute other Linux commands (grep, mv, rm, etc.) on the files and directories you find, which makes find extremely powerful. 

How to use the Linux ‘scp’ command without a password to make remote backups alvin August 7, 2018 - 11:25am

Summary: How to create a public and private key pair to use ssh and scp without using a password, which lets you automate a remote server backup process.

Over the last two years I've ended up creating a large collection of websites and web applications on a variety of Linux servers that are hosted with different companies like GoDaddy and A2 Hosting. I recently embarked on a mission to automate the backup processes for all these sites, and as a result of this effort, I thought I'd share what I've learned here.