Guides | Linuxaria

Counting and listing hard links on Linux

Aug 132014

Article by giannis_tsakiris first posted on http://www.giannistsakiris.com

A hard link is actually nothing more than a regular directory entry, which in turn can be seen as a pointer to the actual file’s data on the disk. The cool thing about hard-links is that a file can be stored once on the disk, and be linked to multiple times, from different locations/entries, without requiring to allocate extra disk space for each file instance.

But then a question arises: Given a specific file on disk, how can someone know whether it is linked to by other directory entries or not? This can be easily answered using the ls command:

giannis@zandloper:/etc$ ls -l passwd -rw-r--r-- 1 root root 1402 2008-03-30 17:49 passwd;

Do you ever wonder what is this small number between the file permissions and the owner in the output of ls’s long listing format (its value is usually “1″ for files, or “2″ for directories)? This number is actually the link-count of the file, when referring to a file, or the number of contained directory entries, when referring to a directory (including the . and .. entries).
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Enabling automatic updates in Centos 7 and RHEL 7

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Aug 092014

In previous posts we’ve seen how to Enable automatic security update in Debian/Ubuntu and in Red hat enterprise or Centos 6, recently I’ve started to work with the new Red Hat Enterprise 7 and I’ve noticed that there are some interesting changes in the way this system can be set to auto update.

An example ?

In Red Hat/Centos 6 you could not set which kind of update you’d like to do, so you could just decide to update for any kind of update (feature,bug or security) or nothing at all, this has changed and now we can fine grain which kind of updates we want to do on our servers.

Linux Terminal: Reptyr attach a running process to a new terminal

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Aug 012014

If, like me, you work on terminals connected via ssh to remote computer/server you are probably used to tmux and screen and so it’s not a problem if you have to close your session, as you’ll be able to easily re-connect when you need it, but sometimes you could forget about using one of these utility.

Started a long-running process over ssh, but have to leave and don’t want to interrupt it?
Just start a screen, use reptyr to grab it, and then kill the ssh session and head on home.

Linux Terminal: inxi – a full featured system information script

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Jul 132014

Sometimes it’s useful to know which components you are using on a GNU/Linux computer or server, you can go with the long way, taking a look at the boot message for all the hardware discovered, use some terminal commands such as lsusb,lspci or lshw or some graphical tools such as hardinfo (my favourite graphical tool) or Inex/CPU-G.

But I’ve discovered on my Linux Mint, that, by default, I’ve now a new option: inxi

inxi it’s a full featured system information script wrote in bash, that easily will show on a terminal all the info of your system.

How to Enable your Debian Squeeze LTS security support !

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Jul 092014

As probably most people know Debian has announced an extended support for Squeeze (AKA Debian 6), so while the “ordinary” support has ended on the 31 may 2014 there is now a Long Term Support (LTS) until the February 2016.
This has been announced by a team of volunteer on April