Posts Tagged ‘tree’

Delete empty files and directories under directory tree in Linux / UNIX / BSD

Wednesday, October 21st, 2020


Sometimes it happens that you end up on your server with a multiple of empty files. The reason for that could be different for example it could be /tmp is overflown with some session store files on a busy website, or due to some programmers Web executed badly written PHP / Python / Perl / Ruby code bug or lets say Content Management System ( CMS ) based website based on WordPress / Joomla / Drupal / Magento / Shopify etc. due to a broken plugin some specific directory could get filled up with plenty of meaningless empty files, that never gets wiped out if you don't care. This could happen if you offer your users to share files online to a public sharing service as WebFTP and some of the local hacked UNIX user accounts decides to make you look like a fool and run an endless loop to create files in your Hard Drive until your small server HDD filesystem of few terabytes gets filled up with useless empty files and due to full inode count on the filesystem your machine running running services gets disfunctional …

Hence on servers with shared users or simply webservers it is always a good idea to keep an eye on filesystem used nodes count by system are and in case if notices a sudden increase of used FS inodes as part of the investigation process on what caused it to check the amount of empty files on the system attached SCSI / SSD / SAS whatever drive.

1. Show a list of free inodes on server

Getting inodes count after logged is done with df command

root@linux-server:~# df -i
Filesystem        Inodes   IUsed     IFree IUse% Mounted on
udev             2041464     516   2040948    1% /dev
tmpfs            2046343    1000   2045343    1% /run
/dev/sdb2       14655488 1794109  12861379   13% /
tmpfs            2046343       4   2046339    1% /dev/shm
tmpfs            2046343       8   2046335    1% /run/lock
tmpfs            2046343      17   2046326    1% /sys/fs/cgroup
/dev/sdc6        6111232  6111232   0   100% /var/www
/dev/sda1       30162944 3734710  26428234   13% /mnt/sda1
/dev/sdd1      122093568 8011342 114082226    7% /backups
tmpfs            2046343      13   2046330    1% /run/user/1000


2. Show all empty files and directories count


### count empty directories ### root@linux-server:~# find /path/ -empty -type d | wc -l

### count empty files only ### root@linux-server:~# find /path/ -empty -type f | wc -l


3. List all empty files in directory or root dir

As you can see on the server in above example the amount of inodes of empty inodes is depleted.
The next step is to anylize what is happening in that web directory and if there is a multitude of empty files taking up all our disk space.

root@linux-server:~# find /var/www -type f -empty > /root/empty_files_list.txt

As you can see I'm redirecting output to a file as with the case of many empty files, I'll have to wait for ages and console will get filled up with a data I'll be unable to easily analyze

If the problem is another directory in your case, lets say the root dir.

root@linux-server:~#  DIR='/';
root@linux-server:~# find $DIR -type f -empty > /root/empty_files_list.txt

4. Getting empty directories list

Under some case it might be that the server is overflowed with empty directories. This is also a thing some malicious cracker guy could do to your server if he can't root the server with some exploit but wants to bug you and 'show off his script kiddie 3l337 magic tricks' :). This is easily done with a perl / python or bash shell endless loop inside which a random file named millions of empty directories instead of files is created.

To look up for empty directories hence use:

root@linux-server:~# DIR='/home';
root@linux-server:~# find  $DIR . -type d -empty > /root/empty_directories_list.txt


5. Delete all empty files only to clean up inodes

Deletion of empty files will automatically free up the inodes occupied, to delete them.

root@linux-server:~# cd /path/containing/multiple/empty-dirs/
root@linux-server:~# find . -type f -empty -exec rm -fr {} \;


6. Delete all empty directories only to clean up inocommanddes

root@linux-server:~# find . -type d -empty -exec rm -fr {} \;


7. Delete all empty files and directories to clean up inodes

root@linux-server:~# cd /path/containing/multiple/empty-dirs/
root@linux-server:~# find . -empty -delete


8. Use find + xargs to delete if files count to delete is too high

root@linux-server:~# find . -empty | xargs rm -r

That's all folks ! Enjoy now your Filesystem to have retrieved back the lost inodes from the jump empty files or directories.

Happy cleaning  🙂

On God and computers and how computers copy God’s creation

Friday, October 25th, 2013

People are copying Gods creation the-tree model people don't invent they copy

I've been thinking for a long time. How computers and involved technology copy God's creation. This kind of thoughts poped up in my mind right after I became a believer. As I'm having a strong IT background I tend to view thinks in world via the prism of my IT knowledge. If I have to learn a new science my mind tend to compare how this translates to my previous knowledge obtained in IT. Probably some other people out there has the same kind of thinking? I'm not sure if this is a geek thinking or it is usual and people from other fields of science tend to also understand the world by using accommodated knowledge in field of profession they practice. Anyways since my days I believed in Jesus Christ, I started to also to compare my so far knowledge with what I've red in Holy Bible and  in the book of The Living of Saints (which btw is unknown to most protestant world). It is very interesting that if you deeply look into how all Information Technology knowledge is organized you can see how Computers resembles the visible God's creation. In reality I came to realization how Moden Man self-deceives himself. We think with every new modern technology we achieved something new revolutionory which didn't existed before. But is it really true? Lets take some technology like Microsoft Active Directory (using LDAP) for example. LDAP structures data in a tree form where each branch could have a number of sub branches (variables). In reality it appears LDAP is not new it a translation of previous already existent knowledge in universe served in a different kind of form. Let me give some other examples, lets pick up the Internet, we claim its a new invention and from human point of view it is. But if we look on it via the prism of existing created world. It is just a interconnection between "BIG DATA" in real world it is absolutely the same latest researches already know all in world is data and all data in world is interconnected. So obviously the internet is another copying of the wonderful things God created in material and for those who can accept (the spiritual world) world. Many who are hard-core atheists will argue that we copy things in the world but all the material world is just a co-incidence. But having in mind that the world is so perfectly tuned "for living beings to exist" it is near to impossible that all this life and perfection emerged by random. The tree structure model is existing everywhere in OS and programming. We can see it in hiearchy of a file system, we can see it in hashes (arrays) in programming and all this just copies the over-simplified model of a real tree (which we know well from Biology is innemous times more complex). Probably the future of computing is in Biotechnologies and people's attempts to copy how living organism works. We know from well from science-fiction and cyberpunk the future should be mostly in Bio-technologies and computer as we know it but even this high-tech next generation technology will be based on existent things. Meaning man doesn't invent something so different he does copy a model and then modify the model according to environment or just makes a combination of a number of models to achieve a next one. Sorry for the rant post but I'm thinking on this for quite a while and I thought i should spit it here and interested to hear what people think and what are the arguments for or against my thesis?

How to mount NTFS Windows XP filesystem on FreeBSD, NetBSD, OpenBSD

Friday, May 11th, 2012

Mounting NTFS hdd partitions on FreeBSD logo picture

A friend of mine bring home a Seagate External Hard Disk Drive using USB 3 as a communication media. I needed to attach the hard disk to my FreeBSD router to transfer him some data, the External HDD is formatted to use NTFS as a main file partition and hence to make the file transfers I had to somehow mount the NTFS partition on the HDD.

FreeBSD and other BSDs, just like Linux does not have embedded NTFS file system mount support.
In order to add an external write support for the plugged hdd NTFS I looked in the ports tree:

freebsd# cd /usr/ports
freebsd# make search name='ntfs'
Port: fusefs-ntfs-2010.10.2
Path: /usr/ports/sysutils/fusefs-ntfs
Info: Mount NTFS partitions (read/write) and disk images
B-deps: fusefs-libs-2.7.4 libiconv-1.13.1_1 libtool-2.4 libublio-20070103 pkg-config-0.25_1
R-deps: fusefs-kmod-0.3.9.p1.20080208_7 fusefs-libs-2.7.4 libiconv-1.13.1_1 libublio-20070103 pkg-config-0.25_1

Port: ntfsprogs-2.0.0_1
Path: /usr/ports/sysutils/ntfsprogs
Info: Utilities and library to manipulate NTFS partitions
B-deps: fusefs-libs-2.7.4 libiconv-1.13.1_1 libublio-20070103 pkg-config-0.25_1
R-deps: libublio-20070103 pkg-config-0.25_1
freebs# cd sysutils/fusefs-ntfs/
freebsd# ls
Makefile distinfo files/ pkg-descr pkg-plist
freebsd# cat pkg-descr
The ntfs-3g driver is an open source, freely available read/write NTFS
driver, which provides safe and fast handling of the Windows XP, Windows
Server 2003 and Windows 2000 filesystems. Almost the full POSIX filesystem
functionality is supported, the major exceptions are changing the file
ownerships and the access rights.

Using ntfs-3g I managed to succeed mounting the NTFS on my old PC running FreeBSD ver. 7_2

1. Installing fuserfs-ntfs support on BSD

Before I can use ntfs-3g, to mount the paritition, I had to install fuserfs-ntfs bsd port, with:

freebsd# cd /usr/ports/sysutils/fusefs-ntfs
freebsd# make install clean

I was curious if ntfsprogs provides other utilities to do the ntfs mount but whilst trying to install it I realized it is already installed as a dependency package to fusefs-ntfs.

fusefs-ntfs package provides a number of utilities for creating, mounting, fixing and doing various manipulations with Microsoft NTFS filesystems.

Here is a list of all the executable utilities helpful in NTFS fs management:

freebsd# pkg_info -L fusefs-ntfs\* | grep -E "/bin/|/sbin|README"

The README and README.FreeBSD are wonderful, reading for those who want to get more in depth knowledge on using the up-listed utilities.

One utility, worthy to mention, I have used in the past is ntfsfix. ntfsfix resolve issues with NTFS partitions which were not unmounted on system shutdown (electricity outage), system hang up etc.

2. Start fusefs (ntfs) and configure it to auto load on system boot

Once fuserfs-ntfs is installed, if its necessery ntfs fs mounts to be permanently supported on the BSD system add fusefs_enable="YES" to /etc/rc.conf(the FreeBSD services auto load conf).

freebsd# echo 'fusefs_enable="YES"' >> /etc/rc.conf

One note to make here is that you need to have also dbus_enable="YES" and hald_enable="YES" in /etc/rc.conf, not having this two in rc.conf will prevent fusefs to start properly. Do a quick grep to make sure this two variables are enabled:

Afterwards fsusefs load up script should be run:

freebsd# /usr/local/etc/rc.d/fusefs start
Starting fusefs.

Another alternative way to load ntfs support on the BSD host is to directly load fuse.ko kernel module:

freebsd# /sbin/kldload fuse.ko

3. Mounting the NTFS partition

In my case, the Seagate hard drive was detected as da0, where the NTFS partition was detected as s1 (da0s1):

freebsd# dmesg|grep -i da0
da0 at umass-sim0 bus 0 target 0 lun 0
da0: Fixed Direct Access SCSI-4 device
da0: 40.000MB/s transfers
da0: 953869MB (1953525164 512 byte sectors: 255H 63S/T 121601C)br />GEOM_LABEL: Label for provider da0s1 is ntfs/Expansion Drive.
GEOM_LABEL: Label for provider da0s1 is ntfs/Expansion Drive.

Therefore further to mount it one can use mount_ntfs (to quickly mount in read only mode) or ntfs-3g for (read / write mode):

If you need to just quickly mount a disk drive to copy some data and umount it with no need for writting to the NTFS partition do;

freebsd# /sbin/mount_ntfs /dev/ad0s1 /mnt/disk

Note that mount_ntfs command is a native BSD command and have nothing to do with ntfs-3g. Therefore using it to mount NTFS is not the same as mounting it via ntfs-3g cmd

freebsd# /usr/local/bin/ntfs-3g -o rw /dev/da0s1 /mnt/disk/

Something, I've noticed while using ntfs-3g is, it fails to properly exit even when the ntfs-3g shell execution is over:

freebsd# ps ax |grep -i ntfs|grep -v grep
18892 ?? Is 0:00.00 /usr/local/bin/ntfs-3g -o rw /dev/da0s1 /mnt/disk/

I dunno if this is some kind of ntfs-3g bug or feature specific to all versions of FreeBSD or it is something local to FBSD 7.2

Thought ntfs-3g, keeps appearing in process list, praise God as of time of writting NTFS support on FreeBSD prooved to be stable.
Read / Write disk operations to the NTFS I tested it with works great. Just about 5 years ago I still remember write mode was still experimental. Now it seems NTFS mounts can be used with no hassle even on production machines.

4. Auto mounting NTFS partition on FreeBSD system boot

There are two approaches towards 'the problem' I can think of.
The better way to auto mount on boot (in my view) is through /etc/fstab use

If /etc/fstab + ntfs-3g is to be used, you will however change the default /sbin/mount_ntfs command to point to /usr/local/bin/ntfs-3g, i.e.:

freebsd# mv /sbin/mount_ntfs /sbin/mount_ntfs.orig
freebsd# ln -s /usr/local/bin/ntfs-3g /sbin/mount_ntfs

Then to mount /dev/da0s1 via /etc/fstab add line:

/dev/ad0s1 /mnt/disk ntfs rw,late 0 0

To not bother with text editor run:

freebsd# echo '/dev/ad0s1 /mnt/disk ntfs rw,late 0 0' >> /etc/fstab

I've red in posts in freebsd forums, there is also a way to use ntfs-3g for mounting partitions, without substituting the original bsd /sbin/mount_ntfs, the exact commands suggested to be used with no need to prior mv /sbin/mount_ntfs to /sbin/mount_ntfs.orig and link it to ntfs is:

/dev/ad0s1 /disk ntfs rw,mountprog=/usr/local/bin/ntfs-3g,late 0 0

For any other NTFS partitions, for instance /dev/ad0s2, /dev/ad2s1 etc. simply change the parititon name and mount points.

The second alternative to adding the NTFS to auto mount is through /etc/rc.local. /etc/rc.local content will be executed very late in system boot. :

echo '/usr/local/bin/ntfs-3g -o rw /dev/da0s1' >> /etc/rc.local

One disadvanage of using /etc/rc.local for mounting the partition is the hanging ntfs-3g in proc list:

freebsd# ps ax |grep -i ntfs|grep -v grep
18892 ?? Is 0:00.00 /usr/local/bin/ntfs-3g -o rw /dev/da0s1 /mnt/disk/

Though, I haven't tested it yet. Using the same methodology should be perfectly working on PC-BSD, DragonFlyBSD, NetBSD and OpenBSD.
I will be glad if someone who runs any of the other BSDs can confirm, following this instructions works fine on these BSDs too.

Editting binary files in console and GUI on FreeBSD and Linux

Thursday, April 26th, 2012

I’ve recently wanted to edit one binary file because there was compiled in the binary a text string with a word I didn’t liked and therefore I wanted to delete. I know I can dig in the source of the proggie with grep and directly substitute my “unwatned text” there but I wanted to experiment, and see what kind of hex binary text editors are for Free OSes.
All those who lived the DOS OS computer era should certainly remember the DOS hex editors was very enjoyable. It was not rare case, where in this good old days, one could simply use the hex editor to “hack” the game and add extra player lives or modify some vital game parameter like put himself first in the top scores list. I even remember some DOS programs and games was possible to be cracked with a text editor … Well it was times, now back to current situation as a Free Software user for the last 12 years it was interesting to see what is the DOS hexeditor like alternatives for FreeBSD and Linux and hence in this article I will present my findings:

A quick search in FreeBSD ports tree and Debian installable packages list, I’ve found a number of programs allowing one to edit in console and GUI binary files.

Here is a list of the hex editors I will in short review in this article:

  • hexedit
  • dhex
  • chexedit
  • hte
  • hexer
  • hexcurse
  • ghex
  • shed
  • okteta
  • bless
  • lfhex

1. hexedit on Linux and BSD – basic hex editor

I’ve used hexedit already on Linux so I’ve used it some long time ago.

My previou experience in using hexedit is not too pinky, I found it difficult to use on Redhat and Debian Linux back in the day. hexedit is definitely not a choice of people who are not “initiated” with hex editting.
Anyways if you want to give it a try you can install it on FreeBSD with:

freebsd# cd /usr/ports/editors/hexedit
freebsd# make install clean

On Debian the hexedit, install package is named the same so installation is with apt:

debian:~# apt-get –yes install hexedit

hexedit screenshot Debian Linux Squeeze

2. Hex editting with chexedit

I’ve installed chexedit the usual way from ports:

freebsd# cd /usr/ports/editors/chexedit
freebsd# make install clean

chexedit is using the ncurses text console library, so the interface is very similar to midnight commander (mc) as you see from below’s screenshot:

Chexeditor FreeBSD 7.2 OS Screenshot

Editting the binary compiled in string was an easy task with chexedit as most of the commands are clearly visible, anyways changing a certain text string contained within the binary file with some other is not easy with chexedit as you need to know the corresponding binary binary value representing each text string character.
I’m not a low level programmer, so I don’t know the binary values of each keyboard character and hence my competence came to the point where I can substitute the text string I wanted with some unreadable characters by simply filling all my text string with AA AA AA AA values…

chexedit on Debian is packaged under a deb ncurses-hexedit. Hence to install it on Deb run:

debian:~# apt-get –yes install ncurses-hexedit

Further on the binary to run chexedit on binary contained within ncurses-hexedit is:

debian:~# hexeeditor

3. Hex Editting on BSD and Linux with hte

Just after trying out chexedit, I’ve found about the existence of one even more sophisticated hexeditor console program available across both FreeBSD and Linux.
The program is called hte (sounds to me a bit like the Indian word for Elephant “Hatti” :))

hte is installable on Debian with cmd:

debian:~# apt-get install ht

On FreeBSD the port name is identical, so to install it I execed:

freebsd# cd /usr/ports/editors/hte
freebsd# make install clean

hte is started on Debian Linux (and presumably other Linux distros) with:

$ hte

On FreeBSD you need to run it with ht command:

freebsd# ht

You see how hte looks like in below screenshot:

ht has the look & feel like midnight commander and I found it easier to use than chexedit and hexeditor
4. hexer VI like interface for Linux

As I was looking through the available packages ready to install, I’ve tried hexer

debian:~# apt-get install –yes hexer

hexer does follow the same standard commands like VIM, e.g. i for insert, a for append etc.

Hexer Debian Linux vim like binary editor screenshot

It was interesting to find out hexer was written by a Bulgarian fellow Petar Penchev 🙂
(Proud to be Bulgarian) – Petar Penchev has his own page on

As a vim user I really liked the idea, the only thing I didn’t liked is there is no easy way to just substitute a string within the binary with another string.

5. hexcurse another ncurses library based hex editor

On Deb install and run via:

debian:~# apt-get –yes install hexcurse
debian:~# hexcurse /usr/bin/mc

Hexcurse Debian Linux text binary editor screenshot

hexcurse is also available on FreeBSD to install it use cmd:

freebsd# cd /usr/ports/editors/hexcurse
freebsd# make install clean

To access the editor functions press CTRL+the first letter of the word in the bottom menu, CTRL+H, CTRL+S etc.
Something I disliked about it is the program search is always in hex, so I cannot look for a text string within the binaries with it.

6. ghex – Editting binary files in graphical environment

If you’re running a graphical environment, take a look at ghex. ghex is a gnome (graphical hex) editor.Installing ghex on Debian is with:

debian:~# apt-get –yes install ghex

To run ghex from terminal type:

debian:~# ghex2

GHex2 GNOME hex binary editor screenshot

To install ghex on FreeBSD (and I assume other BSDs), install via port:

freebsd# cd /usr/ports/editors/ghex
freebsd# make install clean

Gnome hex editor have plenty of tools, useful for developers to debug binary files.

Some nice tools one can find are under the the menus:

Windows -> Character Table

This will show a complete list of each keyboard sent character in ASCII, Hex, Decimal, Octal and Binary

Screenshot ghex Character table Debian Linux

Another useful embedded tool in ghex is:

Windows -> Type Convertion Dialog

Ghex type convertion dialog screenshot

Note that if you want to use the Type Convertion Dialog tool to find the representing binary values of a text string you will have to type in the letters one by one and save the output within a text file and later you can go and use the same editor to edit the text string within the binary file you like.

I’m not a programmer but surely for programmers or people who want to learn some binary counting, this 2 ghex edmebbed tools are surely valuable.

To conclude even though there are plenty of softwares for hex editting in Linux and BSD, none of them is not so easy to use as the old DOS hexdedit tool, maybe it will be a nice idea if someone actually rewrites the DOS tool and they package it for various free operating systems, I’m sure many people will find it helpful to have a 1:1 equivalent to the DOS tool.

7. Shed pico like interfaced hex editor

For people, who use pico / nano as a default text editor in Linux shed will probably be the editor of choice as it follows the command shortcuts of picoOn Deb based distros to install it run:

debian:~# apt-get install –yes shed

shed pico like hex binary editor Linux

Shed has no BSD port as of time of writting.8. Okteta a KDE GUI hex editor

For KDE users, I found a program called okteta. It is available for Deb based Linuxes as deb to install it:

debian:~# apt-get –yes install okteta

Screenshot Okteta Debian GNU / Linux Squeeze

As of time of writting this article there is no okteta port for BSDs.
Okteta has plenty of functions and even has more of a functions than ghexedit. Something distinctive for it is it supports opening multiple files in tabs.

9. lfhex a large file text editor

lfhex is said to be a large (binary) file text editor, I have not tested it myself but just run it to see how it looks like. I don’t have a need to edit large binary files too, but I guess there are people with such requirements too 🙂

lfhex - Linux The Large file hex editor

To install lfhex on Debian:

debian:~# apt-get install –yes lfhex

lfhex has also a FreeBSD port installable via:

freebsd# cd /usr/ports/editors/lfhex
freebsd# make install clean

10. Bless a GUI tool for editting large hex (binary) files

Here is the description directly taken from the BSD port /usr/ports/editors/bless

Bless is a binary (hex) editor, a program that enables you to edit files asa sequence of bytes. It is written in C# and uses the Gtk# bindings for theGTK+ toolkit.

To install and use ot on deb based Linuxes:

debian:~# apt-get install –yes bless

On BSD installation is again from port:

freebsd# cd /usr/ports/editors/bless
freebsd# make install clean

Something that makes bless, maybe more desirable choice for GUI users than ghex is its availability of tabs. Opening multiple binaries in tabs will be useful only to few heavy debuggers.

Bless GUI hex editor Debian Linux tabs opened screenshot

11. Ghextris – an ultra hard hacker tetris game 🙂

For absolute, hacker / (geeks), there is a tetris game called ghextris. The game is the hardest tetris game I ever played in my life. It requires more than regular IQ and a lot of practice if you want to become really good in this game.

To enjoy it:

debian:~# apt-get –yes install ghextris

Ultra hrad hardcore hackers game ghextris screenshot

Unfortunately there is no native port of ghextris for BSD (yet). Anyhow, it can be probably run using the Linux emulation or even compiled from source.
Well that’s all I found for hexedit-ing, I’ll be happy to hear if someone can give me some feedback on his favourite editor.

How to upgrade single package with their dependencies on Debian and Ubuntu Linux

Friday, March 16th, 2012

Debian GNU / Linux apt-get upgrade a package selection of a whole bunch of packages ready to upgrade apt artistic logo

Are you a Debian System Administrator and you recently run apt-get upgrade && apt-get upgrade finding out there are plenty of new packagesfor upgrade? Do you need only a pre-selected number of packages to upgrade with apt?
I run apt-get update && apt-get upgrade on one of our company Debian servers, just to see there are a number of packages to be upgraded among which there was some I didn't wanted to upgrade. Here is a little paste output from apt-get upgrade:

debian:~# apt-get update && apt-get upgrade
Hit squeeze/updates Release.gpg
Hit squeeze/updates/main amd64 Packages
Fetched 128 kB in 0s (441 kB/s)
Reading package lists... Done
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be upgraded:
at imagemagick libdbd-pg-perl libfreetype6 libmagickcore3 libmagickcore3-extra libmagickwand3 libmysqlclient16 mysql-client
mysql-client-5.1 mysql-common mysql-server mysql-server-5.1 mysql-server-core-5.1
Do you want to continue [Y/n]
14 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

From first sight it seems logical to issue apt-get upgrade packagename to upgrade only single package with its package dependencies, instead of the whole group the above packs. However doing:
apt-get upgrade imagemagick will still try to upgrade all the packages instead of just imagemagick and its dependency package deb libmagickcore3

debian:~# apt-get upgrade imagemagick
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be upgraded:
at imagemagick libdbd-pg-perl libfreetype6 libmagickcore3 libmagickcore3-extra libmagickwand3 libmysqlclient16 mysql-client
mysql-client-5.1 mysql-common mysql-server mysql-server-5.1 mysql-server-core-5.1
14 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Do you want to continue [Y/n]

Doing all package,upgrade is not a good idea in my case, since upgrading mysql-server will require a MySQL server restart (something which we cannot afford to do right now) on this production server.
MySQL server restart during upgrade is never a good idea especially on productive busy (heavy loaded) SQL servers.
A restart of the MySQL server serving thousands of requests per second could lead often to crashed tables and hence temporary server downtime etc.

Still it is a good idea to upgrade the rest of packages with their newer versions. For exmpl. to upgrade; imagemagick, at , libfreetype6 and so on.

In order to upgrade only this 3 ones and their respective package dependencies, issue:

debian:~# apt-get --yes install imagemagick at libfreetype6

Repeat the apt-get install command with passing all the single package name you want to be upgraded and voila you're done :).
Be sure the apt-get install packagename upgrade doesn't require also upgrade of myssql-server, mysql-client, mysql-common or mysql-server-core-5.1 or any of the package name you want to preserve from upgrading.

How to count how many files are in a directory with find on Linux

Tuesday, February 21st, 2012

how to count how many directories are on your linux server

Did you ever needed to count, how many files in a directory are there?
Having the concrete number of files in a directory is not a seldom task but still very useful especially for scripts or simply for the sake of learning

The quickest and maybe the easiest way to count all files in a directory in Linux is with a combination of find and wc commands:

Here is how;

linux:~# cd ascii
linux:~/ascii# find . -type f -iname '*' -print |wc -l

This will find and list all matched files in any directory and subdirectories, print them out and count them with wc command.
The -type f argument instructs find to look only for files.

Other helpful variance of finding and listing all files in a directory and subdirectories is to list and count all the files with a certain file extension under a directory. For example, lets list all text files (.txt) contained in a directory and all level sub-directories:

linux:~/ascii# find . -type f -iname '*.txt' -print |wc -l

If you need to check the number of files in a directory for multiple directories on a server and you're aiming at doing it efficienly, issung above find .. | wc code will definitely be not a good choice. If used it will generate heavy load for the system and along with that will complete the execution in ages if issued on a large number of files containing dirs.

Thanksfully if efficiency is targetted, there is a command written in C called tree which is more efficient than find.
To count the number of files in dir but using tree :

linux:~# cd ascii
linux:/ascii# tree | tail -n 1
32 directories, 407 files

By default tree prints info for both the number of found files and directories.
To print out only the files matched, awk comes handy, e.g.:

linux:/ascii# tree |tail -n 1| awk '{ print $3 }'407

To list only the number of files in a directory without its existing sub-directories ls + wc use is also possible:

linux:~/ascii# ls -l | grep ^- | wc -l68

This result the above command would produce is +1 more than the real number of files, as it counts the directory ".." as one file (in UNIX / LINUX everything is file).

A short one liner script that can calculate all files correctly by substracting 1 is and hence present correct result on number of files is like so:

linux:~/ascii# var=$(ls -l | grep ^- | wc -l); var=$(($var - 1)); echo $var

ls can be used to calculate the number of 1-st level sub-directories under certain directory for instance:

linux:~/ascii# ls -l |grep ^d|wc -l

You see the ascii directory has 25 subdirectories in its 1st level.

To check symlinks under a directory with ls the command would be:

linux:~/ascii# ls -l | grep ^l | wc -l

Note above 3 ls | grep … examples, will not work properly if the directory contains files with SUID or some special properties set.
Hence to get the same 3 results for active files, directories and symbolic links, a one liner similar to the one below can be used instead:

linux:~/ascii# for t in files links directories; do echo `find . -type ${t:0:1} | wc -l` $t; done 2> /dev/null
407 files
0 links
33 directories

This will show statistics about all files, links and directories for all directory sub-levels.
Just in case if there is need to only count files, links and directories without directory recursion enabled, use:

linux:~/ascii# for t in files links directories; do echo `find . -maxdepth 1 -type ${t:0:1} | wc -l` $t; done 2> /dev/null
68 files
0 links
26 directories

Anyways the above bash loop will be slow, for directories containing thousands of files. For better performance the equivallent of above bash loop rewritten in perl would be:

linux:~/ascii# ls -l |perl -e 'while(<>){$h{substr($_,0,1)}+=1;} END {foreach(keys %h) {print "$_ $h{$_}\n";}}'
- 68
d 25
t 1
In any case the most preferrable and efficient way to count files en directories is by using tree command.
In my view using always tree command instead of code "hacks" is smart idea.

In Slackware tree command is part of the base install, on Debian and CentOS Linux, tree cmd is not part of the base system and requires install via apt / yum e.g.:

debian:~# apt-get --yes install tree

[root@centos:~ ]# yum --yes install tree

Happy counting 😉

The Legend of the Christmas Tree and Why do we put Christmas trees at home in Christmas time? :)

Thursday, January 12th, 2012

Why we put Pine tree / Fir in Christmas origins of Christmas tree / Legends for the Christmas Tree

Christmas has just passed away. As a Christian I was curious what is the reason in so many Christian countries, we decorate Pine trees and I did a quick research on the topic. In this small article, I'll present my findings.

Observing the Christmas Pine Tree tradition has been quite ancient and probably according to many sources dates back to the XIIth century.
The first written records of a Christmas tree are of an anonymous Frenchman who visited Strasbourg, Germany in 1601. His description of the decoratd pine tree says like "wafers and golden sugar-twists (Barley sugar), roses cut out of many-colored paper, apples, gold foil and sweets."

Later in the 1800s, the local German Christmas pine tree tradition was spread across America by German emmigrants.
In UK the Pine tree decorating tradition appeard in 1841, where a royalty (Prince Albert) decorated his castle (Winston Castle).

A little later after the Queen Victoria adopted the pine tree, United Kingdom citizens started to decorate pine trees for themselves, folliwng the highly regarded Queen.
Usually the pine tree has historically been decorated with gifts as well as an Bright star is put atop.

One of the Christian interpretations for the Christmas tree is that it represents the same Cross (tree) on which Christ was crucifixed. Then after Christ's resurrection because of (or through that) tree, the humanity received the Lord big spiritual blessings. These blessings are represented by the gifts decorated on the Fir tree. The pine tree itself is in Christianity a reference for the symbol of Salvation that we received came from the Holy Cross, where our saviour was crucified.

The Fir is decorated with lights to represent the joy and the lights of Christmas (that burns in our hearts), the star atop the tree is a reminder of the Star that rised in the East during the night of Christ's birth as we read in the gospels.

Roman Catholic Church Christmas Pine Trees
Decorating Pine trees is commonly observed mostly in Roman Catholic Church and often followed by some protestant denominations and less used in Orthodox Church (though this is changing nowdays).

In Eastern Europe, the Christmas tree appeared quite Legends about the Christmas Fir Treelate and the whole concept was unknown in the Orthodox Christian countries, just until the end of the 19th century.

With the recent severe globalization the pine tree was silenty adopted in almost all parts of the world, including even communist countries and even sometimes in muslim ones.
Enormous Fir Tree in Tarnovo city hill Bulgaria

Unfortunately, the relation between the Fir tree and our Christian faith is little known today and with the years to come it will be less and less associated with Christianity.

Here are few interesting legends which I found explaining, some of the possible roots of the Christmas tree decoration:

Legends about the Christmas Fir Tree

1. Legend of the Pine Tree Saving the Holy Family

When the Holy family was pursued by Herod's soldiers, many plants offered to provide them with shelter.
One such plant was the Pine tree. With Mary too weary to travel any longer, the family stopped at the edge of a forest to rest.
A gnarled old Pine which had grown hollow with the years invited them to rest within its trunk.
Then, it closed its branches down upon them, keeping the family safe until the soldiers had passed.
Upon leaving, the Christ Child blessed the Pine and the imprint of his tiny hand was left forever in the tree's fruit… the Pine cone.
If a cone is cut lengthwise, the hand may still be seen.

2. Pine tree and Easter Legend

Pine tree on cones on Easter forms Cross shape

There is a legend that pine trees "know" when it's Easter.
The pine trees start their new growth in the weeks before Easter.
If you look at the tops of the pine trees two weeks before Easter you'll see the yellow shoots.
As the days get closer to Easter Sunday, the tallest shoot will branch off and form a cross.
By the time Easter Sunday comes around, you will see that most of the pine trees will have small yellow crosses on all of the tallest shoots.
This really happens we live where there are lots of pines,
and each year this actually happens, it is amazing to watch,
and the process of the new growth appears as crosses on the ends
of each branch.

I've not personally observed that, but according to people who live in pine tree forest areas this is a fact.

3. Legend about M. Luther and the Pine tree

Martin Luther, founder of the Protestant religion, was taking a stroll through the woods late one night.
The sky was clear and many stars were shining through the branches of the trees,
giving the impression of twinkling lights.
Luther was so captivated and inspired by the beautiful brilliance of the sight
that he cut down a small evergreen and brought it home.
He recreated the stars by placing candles upon the tree's branches to imitate
their radiance and presented it to his children.

This story explains why, the pine tree become so wide spread initially in the "western world", as it gives some connection between the Pine tree and Protestant Christianity.

4. The Children Legend of the Fir Tree (Kids Story)

On the night of the Christ Child's birth, all living creatures, both flora and fauna, traveled to Bethlehem bearing gifts.
The Olive tree, for example, brought its fruit and the Palm tree its dates.
But the little Fir tree had no gift and was so tired that it was unable to resist when the larger trees pushed it into the background and hid it from view.
But then, a nearby Angel took pity and commanded a cluster of stars to descend and rest upon its delicate boughs.
When the Baby Jesus beheld this lovely lighted tree, he smiled and blessed it,
declaring henceforth that Fir trees should always be filled with lights at
Christmastime to please little children.
When Christianity first came to Northern Europe, three personages representing
virtues were dispatched from Heaven to place lights on the original Christmas tree.
These personages were Faith, Hope and Charity.
Their search was long, since they were required to find a tree as high as hope, as great as love and as sweet as charity.
In addition, the tree had to bear the sign of the cross on every bough.
Their search finally ended in the forests of the North where they found the Fir.
Lit by the radiance of the stars, it became the first Christmas tree.
The triangular design of the Fir has also been usedto describe the Holy Trinity of God the Father, The Son and The Holy Spirit.
Eventually, converts began to revere the Fir as God's Tree…as they had once revered the Oak.
By the Twelfth Century it was being hung, upside-down, from ceilings at Christmastime
in Central Europe, as a symbol of Christianity.

5. The Paradise Tree Legend

A very old and delightful European custom centers around decorating a Fir tree with apples and small white wafers which represents the Holy Eucharist.
These wafers were later replaced by small pieces of pastry cut into the shapes of stars, angels, hearts, flowers and bells.
Eventually additional pastries were introduced bearing the shapes of men, birds, roosters and other animals.

During the middle Ages, around the Eleventh century, religious theater was born.
One of the most popular plays …
The German mystery play concerned Adam and Eve and their fall and expulsion from the Garden of Eden, represented by a Fir tree hung with apples.
This tree was symbolic of both the Tree of Life and the Tree of Discernment of Good and Evil, which stood in the center of Paradise.
The play ended with the prophecy of a coming Saviour. For this reason, it was often enacted during Advent.

The one piece of scenery, the "Paradeisbaum" or "Paradise Tree" become a popular object and was often set up in churches.
Eventually it also found its way in private homes and became symbol of the Saviour.
Since the tree was representative not only to Paradise and the fall of man, but also the premise of salvation.
It was hung not merely with apples, but with bread of wafers (Holy Eucharist) and often sweet to represent the sweetness of redemption.
In some areas of Bavaria, fir branches and little trees decorated with lights, apples and tinsel are still called "Paradeis".

According to some other Christian legends, it was a Fir tree that grew as the Tree of Life in the Garden of Eden.
When Eve plucked its fruit, the foliage and flowers shrank to nothing but needles.
Only on the night of Nativity would the Fir tree bloom again a moment marked perhaps by the Christmas tree we Christians use.

Of course these are just legends and as with every legend there is plenty of romantism included.
Nevertheless I consider most legends similar to proverbs contain deep truth and contain truthful facts. Moreover knowing the legends of our forefathers connect us to who and what we are and from antropological point of view is precious knowledge, we should try to sustain and spread to our children.

Pingus – A Lemmings like arcade game for GNU / Linux and FreeBSD (Free Lemmings Clone)

Monday, January 2nd, 2012

Some might remember Psychosis Lemmings that we used to enjoy back in the glorious days of DOS 😉 I remember Lemmings used to be among the played game in one line with other top arcades like Dangerous Dave, Commander Keen, Xenon etc.
The game used to be quite unique for the time and it was quite cool that it worked on quite old machines lime my old 8086 XT with 640kb of memory. It even supported two player mode! 😉

Lemmings arcade screenshot

I was happy to find out actually Lemmings remake is available in the Free Software OS realm . These Lemmings clone game is called Pingus
Instead of governing a group of lemmings which had to move to an exit door by making a save path using various tools and combination of team member character skills, the main heroes in Pingus are cute little penguins 😉

Screenshot Pingus, Lemmings game clone for Linux and FreeBSD

Pingus is built on TOP of SDL libraries and has a combination of awesome graphics and enjoyable music soundtrack and as a game play is a way better than its original predecessor.
If i have to to rank this game I would put it among the best 20 free software games ever produced for Linux / BSD.

ScreenShot Pingus on Debian Linux

pingus is available for almost all kind of Linux distritubions as well as is included in the FreeBSD port tree:

On Debian its available as a package ready to be installed with aptitude or apt by issuing:

debian:~# aptitude install pingus

For FreeBSD pingus is installed via ports tree, by running cmds:

freebsd# cd /usr/ports/games/pingus
freebsd# make install && make install clean

By default pingus will run in a Windowed mode, to run the game in fullscreen you will have to run it with the -f switch via terminal, or by pressing ALT+F2 in GNOME and typing:

$ pingus -f

The game is quite hard to complete in that resembling the lemmings. It has an embedded Mapeditor , by which new levels can be easily constructed and sent to the game developers (in that way helping the game development).

Pingus is also multi-platform, licensed under GPL2 and is also ported for Mac OSX and MS Windows, allowing others non free software users enjoy.
Pingus Windows and MacOS X binary as well as source can be downloaded here

Pingus Lemmings like Free Software Game for Linux BSD level screenshot

Playing Pingus has few benefits, one is it can be nice to kill some boredom (for sysadmins) or / and bring some good past gaming memories. It's also good for developing some elder people strategic thinking as well as very suitable for little children to help develop their intellectual (thinking) in solving complex consequential tasks. Pingus could also be beneficial for teens to develop organizational and math skills.

How to crack password protected rar and 7z files on GNU / Linux

Friday, October 7th, 2011

break / crack password protected rar, zip archives on Linux and FreeBSD rarcrcack

RarCrack is able to crack rar and 7z archive files protected by password on Linux.
The program is currently at release version 0.2, so its far from perfection, but at least it can break rars.

RarCrack is currently installable on most Linux distributions only from source, to install on a random Linux distro, download and make && make install . RarCrack’s official site is here, I’ve mirrored the current version of RarCrack for download here . To install rarcrack from source using the mirrored version:

linux:~# wget
linux:~# tar -jxvvf rarcrack-0.2.tar.bz2
linux:~# cd rarcrack-0.2
linux:~/rarcrack-0.2# make
linux:~/rarcrack-0.2# make install

On FreeBSD, rarcrack is available and installable via the ports tree, to install on FreeBSD:

freebsd# cd /usr/ports/security/rarcrack
freebsd# make && make install

To use RarCrack to crack rar, zip or 7z archive file:

freebsd% rarcrack rar_file_protected_with_password.rar --type rar

The argument –type rar is optional, in most archives RarCrack should detect the archive automatically. The –type option could also take the arguments of rar and 7z .

I’ve created a sample rar file protected with password linux_then_and_now.png.rar . The archive linux_then_and_now.png contains a graphic file illustrating the linux growth in use in computers, mobiles and servers. linux_then_and_now.png.rar is protected with the sample password parola

RarCrack also supports threads (a simultaneous instance spawned copies of the program). Using threads speeds up the process of cracking and thus using the –threads is generally a good idea. Hence a good way to use rarcrack with the –threads option is:

freebsd% rarcrack linux_then_and_now.png.rar --threads 8 --type rar
RarCrack! 0.2 by David Zoltan Kedves (
INFO: the specified archive type: rar
INFO: cracking linux_then_and_now.png.rar, status file: linux_then_and_now.png.rar.xml
Probing: '0i' [24 pwds/sec]
Probing: '1v' [25 pwds/sec]

RarCrack‘s source archive also comes with three sample archive files (rar, 7z and zip) protected with passwords for the sake of testing the tool.
One downside of RarCrack is its extremely slow in breaking the passwords on my Lenovo notebook – dual core 1.8ghz with 2g ram it was able to brute force only 20-25 passwords per second.
This means cracking a normal password of 6 symbols will take at least 5 hours.
RarCrack is also said to support cracking zip passwords, but my tests to crack password protected zip file did not bring good results and even one of the tests ended with a segmentation fault.

To test how rarcrack performs with password protected zip files and hence compare if it is superior or inferior to fcrackzip, I used the fcrackzip’s sample pass protected zip

hipo@noah:~$ rarcrack --threads 8 --type zip
2 by David Zoltan Kedves (
INFO: the specified archive type: zip
INFO: cracking, status file:
Probing: 'hP' [386 pwds/sec]
Probing: 'At' [385 pwds/sec]
Probing: 'ST' [380 pwds/sec]

As you can see in above’s command output, the zip password cracking rate of approximately 380 passwords per second is a bit quicker, but still slower than fcrackzip.

RarCrack seg faults if cracking a pass protected zip is passed on without specifying the –type zip command arguments:

linux:~$ rarcrack --threads 8
RarCrack! 0.2 by David Zoltan Kedves (
Segmentation fault

While talking about cracking protected rar and zip archives with password, its worthy to mention creating a password protected archive with Gnome Desktop on Linux and FreeBSD is very easy.

To create the password protected archive in Gnome graphic environment:

a. Point the cursor to the file you want to archive with password

Gnome pointing file properties drop down menu

b. Press on Other Options and fill in the password in the pwd dialog

Linux protect rar with password on Gnome Desktop

I think as of time of writting, no GUI frontend interface for neither RarCrack or FcrackZip is available. Lets hope some good guy from the community will take the time to write extension for Gnome to allow us to crack rar and zip from a nice GUI interface.