Archive for July, 2019

Why du and df reporting different on a filesystem / How to fix inconsistency between used space on FS and disk showing full strangeness

Wednesday, July 24th, 2019

linux-why-du-and-df-shows-different-result-inconsincy-explained-filesystem-full-oddity

If you're a sysadmin on a large server environment such as a couple of hundred of Virtual Machines running Linux OS on either physical host or OpenXen / VmWare hosted guest Virtual Machine, you might end up sometimes at an odd case where some mounted partition mount point reports its file use different when checked with
df
cmd than when checked with du command, like for example:
 

root@sqlserver:~# df -hT /var/lib/mysql
Filesystem   Type  Size Used Avail Use% Mounted On
/dev/sdb5      ext4    19G  3,4G    14G  20% /var/lib/mysql

Here the '-T' argument is used to show us the filesystem.

root@sqlserver:~# du -hsc /var/lib/mysql
0K    /var/lib/mysql/
0K    total

1. Simple debug on what might be the root cause for df / du inconsistency reporting

Of course the basic thing to do when in that weird situation is to be totally shocked how this is possible and to investigate a bit what is the biggest first level sub-directories that eat up the space on the mounted location, with du:

# du -hkx –max-depth=1 /var/lib/mysql/|uniq|sort -n
4       /var/lib/mysql/test
8       /var/lib/mysql/ezmlm
8       /var/lib/mysql/micropcfreak
8       /var/lib/mysql/performance_schema
12      /var/lib/mysql/mysqltmp
24      /var/lib/mysql/speedtest
64      /var/lib/mysql/yourls
144     /var/lib/mysql/narf
320     /var/lib/mysql/webchat_plus
424     /var/lib/mysql/goodfaithair
528     /var/lib/mysql/moonman
648     /var/lib/mysql/daniel
852     /var/lib/mysql/lessn
1292    /var/lib/mysql/gallery

The given output is in Kilobytes so it is a little bit hard to read, if you're used to Mbytes instead, do

 # du -hmx –max-depth=1 /var/lib/mysql/|uniq|sort -n|less

I've also investigated on the complete /var directory contents sorted by size with:

 # du -akx ./ | sort -n
5152564    ./cache/rsnapshot/hourly.2/localhost
5255788    ./cache/rsnapshot/hourly.2
5287912    ./cache/rsnapshot
7192152    ./cache


Even after finding out the bottleneck dirs and trying to clear up a bit, continued facing that inconsistently shown in two commands and if you're likely to be stunned like me and try … to move some files to a different filesystem to free up space or assigned inodes with a hope that shown inconsitency output will be fixed as it might be caused  due to some kernel / FS caching ?? and this will eventually make the mounted FS to refresh …

But unfortunately, if you try it you'll figure out clearing up a couple of Megas or Gigas will make no difference in cmd output.

In my exact case /var/lib/mysql is a separate mounted ext4 filesystem, however same issue was present also on a Network Filesystem (NFS) and thus, my first thought that this is caused by a network failure problem or NFS bug turned to be wrong.

After further short investigation on the inodes on the Filesystem, it was clear enough inodes are available:
 

# df -i /var/lib/mysql
Filesystem       Inodes  IUsed   IFree IUse% Mounted on
/dev/sdb5      1221600  2562 1219038   1% /var/lib/mysql

So the filled inodes count assumed issue also has been rejected.
P.S. (if you're not well familiar with them read manual, i.e. – man 7 inode).
 

– Remounting the mounted filesystem

To make sure the filesystem shown inconsistency between du and df is not due to some hanging network mount or bug, first logical thing I did is to remount the filesytem showing different in size, in my case this was done with:
 

# mount -o remount,rw -t ext4 /var/lib/mysql

For machines with NFS remote mounted storage locations, used:

# mount -o remount,rw -t nfs /var/www


FS remount did not solved it so I continued to ponder what oddity and of course I thought of a workaround (in case if this issues are caused by kernel bug or OS lib issue) reboot might be the solution, however unfortunately restarting the VMs was not a wanted easy to do solution, thus I continued investigating what is wrong …

Next check of course was to check, what kind of network connections are opened to the affected hosts with:
 

# netstat -tupanl


Did not found anything that might point me to the reported different Megabytes issue, so next step was to check what is the situation with currently opened files by running processes on the weird df / du reported systems with lsof, and boom there I observed oddity such as multiple files

# lsof -nP | grep '(deleted)'

COMMAND   PID   USER   FD   TYPE DEVICE    SIZE NLINK  NODE NAME
mysqld   2588  mysql    4u   REG 253,17      52     0  1495 /var/lib/mysql/tmp/ibY0cXCd (deleted)
mysqld   2588  mysql    5u   REG 253,17    1048     0  1496 /var/lib/mysql/tmp/ibOrELhG (deleted)
mysqld   2588  mysql    6u   REG 253,17       777884290     0  1497 /var/lib/mysql/tmp/ibmDFAW8 (deleted)
mysqld   2588  mysql    7u   REG 253,17       123667875     0 11387 /var/lib/mysql/tmp/ib2CSACB (deleted)
mysqld   2588  mysql   11u   REG 253,17       123852406     0 11388 /var/lib/mysql/tmp/ibQpoZ94 (deleted)

Notice that There were plenty of '(deleted)' STATE files shown in memory an overall of 438:

# lsof -nP | grep '(deleted)' |wc -l
438


As I've learned a bit online about the problem, I found it is also possible to find deleted unlinked files only without any greps (to list all deleted files in memory files with lsof args only):

# lsof +L1|less


The SIZE field (fourth column)  shows a number of files that are really hard in size and that are kept in open on filesystem and in memory, totally messing up with the filesystem. In my case this is temp files created by MYSQLD daemon but depending on the server provided service this might be apache's www-data, some custom perl / bash script executed via a cron job, stalled rsync jobs etc.
 

2. Check all the list open files with the mysql / root user as part of the the server filesystem inconsistency debugging with:

– Grep opened files on server by user

# lsof |grep mysql
mysqld    1312                       mysql  cwd       DIR               8,21       4096          2 /var/lib/mysql
mysqld    1312                       mysql  rtd       DIR                8,1       4096          2 /
mysqld    1312                       mysql  txt       REG                8,1   20336792   23805048 /usr/sbin/mysqld
mysqld    1312                       mysql  mem       REG               8,21      24576         20 /var/lib/mysql/tc.log
mysqld    1312                       mysql  DEL       REG               0,16                 29467 /[aio]
mysqld    1312                       mysql  mem       REG                8,1      55792   14886933 /lib/x86_64-linux-gnu/libnss_files-2.28.so

# lsof | grep root
COMMAND    PID   TID TASKCMD          USER   FD      TYPE             DEVICE   SIZE/OFF       NODE NAME
systemd      1                        root  cwd       DIR                8,1       4096          2 /
systemd      1                        root  rtd       DIR                8,1       4096          2 /
systemd      1                        root  txt       REG                8,1    1489208   14928891 /lib/systemd/systemd
systemd      1                        root  mem       REG                8,1    1579448   14886924 /lib/x86_64-linux-gnu/libm-2.28.so

Other command that helped to track the discrepancy between df and du different file usage on FS is:
 

# du -hxa  / | egrep '^[[:digit:]]{1,1}G[[:space:]]*'
 

3. Fixing large files kept in memory filesystem problem


What is the real reason for ending up with this file handlers opened by running backgrounded programs on the Linux OS?
It could be multiple  but most likely it is due to exceeded server / client interactions or breaking up RAM or HDD drive with writing plenty of logs on the FS without ending keeping space occupied or Programming library bugs used by hanged service leaving the FH opened on storage.

What is the solution to file system files left in memory problem?

The best solution is to first fix custom script or hanged service and then if possible to simply restart the server to make the kernel / services reload or if this is not possible just restart the problem creation processes.

Once the process is identified like in my case this was MySQL on systemd enabled newer OS distros, just do:

# systemctl restart mysqld.service


or on older init.d system V ones:

# /etc/init.d/service restart


For custom hanged scripts being listed in ps axuwef you can grep the pid and do a kill -HUP (if the script is written in a good way to recognize -HUP and restart the sub-running process properly – BE EXTRA CAREFUL IF YOU'RE RESTARTING BROKEN SCRIPTS as this might cause your running service disruptions …).

# pgrep -l script.sh
7977 script.sh


# kill -HUP PID

Now finally this should either mitigate or at best case completely solve the reported disagreement between df and du, after which the calculated / reported disk space should be back to normal and show up approximately the same (note that size changes a bit as mysql service is writting data) constantly extending the size between the two checks.

# df -hk /var/lib/mysql; du -hskc /var/lib/mysql
Filesystem       Inodes  IUsed   IFree IUse% Mounted on
/dev/sdb5        19097172 3472744 14631296  20% /var/lib/mysql
3427772    /var/lib/mysql
3427772    total

What we learned?

What I've explained in this article is why and how it comes that 'zoombie' files reside on a filesystem
appearing to be eating disk space on a mounted local or network partition, giving strange inconsistent
reports, leading to system service disruptions and impossibility to have correctly shown information on used
disk space on mounted drive.

I went through with some standard logic on debugging service / filesystem / inode issues up explainat, that led me to the finding about deleted files being kept in filesystem and producing the filesystem strange sized / showing not correct / filled even after it was extended with tune2fs and was supposed to have extra 50GBs.

Finally it was explained shortly how to HUP / restart hanging script / service to fix it.

Some few good readings that helped to fix the issue:

What to do when du and df report different usage is here
df in linux not showing correct free space after file removal is here
Why do “df” and “du” commands show different disk usage?
 

How to make Samba smbfs / cifs mount share location with user / pass credentials authenticate via file stored credentials

Friday, July 19th, 2019

how-to-use-username-and-password-to-authenticate-to-samba-share-server-or-linux-share-server-linux-samba-logo
That's pretty trivial and perhaps if you had to manage samba server or cifs on a Linux host you already know it but for beginners, that might be interesting.

So in this short article I will explain how to make configure smbfs / cifs authentication from Linux host A client to Linux host B server running smbd and nmbd samba server (which is the smfs / cifs share server) by using external authentication file for either mount command or if /etc/fstab used to automatically authenticate using a preconfigured mount saba share via /etc/fstab.

Before you start to do anything with samba on Linux host A client machine, you will need as a minimum to have installed cifs-utils or smbfs (assuming you're on Debian Linux like you can check with dpkg -l and if missing install it via:

apt-get install cifs-utils

Or on older systems or for smbfs support

apt-get install smbfs

The general mount smbfs share command without specified external credentials file would look like so:

mount //mynetworksharename/ /shares/data -o username=myusername, password=mypassword


So how to use external auth file to prevent samba shares  users and passwords to not be stored in root user history all the time?

To do so it is pretty straight forward all you need to do is to create a single user / pass credentials variable defined lets say to file called .smbcredentials or .cifs under some directory lets /root/.smbcredentials.

One note here is (many people prefer to store the password under /root) for security reasons as root directory is usually readable only by administrator and would prevent a non-privileged user to read the user / pass which are stored in plain text.

.smbcredentials is described in mount.cifs man page, here is what it says about credentials variable understood by mount / mount.cifs command  file syntax:
 

credentials=filename
    specifies a file that contains a username and/or password. The format of the file is:

         username=value
         password=value


For a CIFS (Common Internet File System) which is a new implementation of old Windows Share (SMB protocol) avaiable in newer Windows XP / 7 / 10 machines, to do the cifs mount manually:
 

mount -v -t cifs //WINSHARESERVER/topsecretfiles /mnt/network/ -o credentials=/mnt/creds-file

or use 

mount.cifs //WINSSHARE/topsecretfiles /mnt/network/ -o credentials=/root/.creds-file

For old smbfs protocol for backward compatibility so older Win 2000 or Winblows server XP PCs configured to also access the Linux samba mount.

mount -t smbfs //WINHARESERVER/topsecretfiles /mnt/network/ -o credentials=/mnt/.smbcredentials


Once you have the defined .smbcredentials file name, be sure to also protect it with properly set permissions like 0600 (rw) readable only for root user. 

chmod 0600 /root/.smbcredentials

Note that in that example .smbcredentials is set to be a hidden file on purpose as this is a hidden file it will make it slightly less seenable if introduder breaks on the server (an example of security through obscurity)

Next lets see how to mount the Windows Samba Share permanently with predefined user / pass server login

For many non secured Windows shares one can use /etc/fstab line definition as simple as:
 

//server-share-name/sharename  /mnt/shares/sharename  cifs  guest,uid=1000,iocharset=utf8  0


For password protected Win Share mounts however, the simplest way to do is via /etc/fstab line add like so:

//servername/sharename  /mnt/shares/sharename  cifs  username=msusername,password=mspassword,iocharset=utf8,sec=ntlm  0  0


Note that the sec=ntlm is optional and remote samba server or Windows Share server version has to support this kind of authentication and in some cases you could safely reove sec=ntlm, just use it, when you know what you're doing. iocharset is good to have as for Russian / Bulgarian e.g.  Cyrillic, Chineese, Indian and other exotic languages and other strange language encoding to be supported and properly shown on the mounted share it should be properly defined …, 

A good permissions would be:

chmod 600 ~/.smbcredentials

To use the external /root/.smbcredentials password it shold be like so:

# cat /root/.smbcredentials

username=msusername
password=mssecretpassword
56#

 

Finally /root/.smbcredentials record should be as so:
 

//share-server-name/sharename /mnt/shares/windowsshare cifs credentials=/home/ubuntuusername/.smbcredentials,iocharset=utf8,sec=ntlm 0 0


Note You should already have

/mnt/shares/windowshare created on server B (the ount client) with:

mkdir -p  /mnt/shares/windowshare


To mount /etc/fstab defined filesystem to mount on next server boot then do

mount /mnt/shares/windowshare


or completely mount / remount all present /etc/fstab filesystems with the common

mount -a


(but here be careful as this might cause you troubles already other NFS or whatever FS is mounted and being read by clients) :

And you the remote Samba Share (mount location) – should be reachable with ping command and traceroute and remote server ports 139, 445 etc. should be up running opened and connectable from server B share-server-name/sharename

If you face some issues when trying to mount remote share with mount -t smbfs / mount.cifs then you can use smbclient with debug option to find out some more on the connectivity / authentication issue by using the smb share server IP address instead of hostnae and lets say a debug level of 3 like so:

smbclient -d3 -L //10.5.8.118/Files -A /root/.smbcredentials

[0] smbclient -d3 -L //10.2.3.111/Files -A /home/acteam/.smbcredentials     lp_load_ex: refreshing parameters
Initialising global parameters
rlimit_max: increasing rlimit_max (1024) to minimum Windows limit (16384)
Processing section "[global]"
WARNING: The "syslog" option is deprecated
added interface eth0 ip=10.2.3.127 bcast=10.2.3.255 netmask=255.255.255.0
Client started (version 4.3.11-Ubuntu).
Connecting to 10.2.3.111 at port 445
Doing spnego session setup (blob length=120)
got OID=1.3.6.1.4.1.311.2.2.30
got OID=1.2.840.48018.1.2.2
got OID=1.2.840.113554.1.2.2
got OID=1.2.840.113554.1.2.2.3
got OID=1.3.6.1.4.1.311.2.2.10
got principal=not_defined_in_RFC4178@please_ignore
GENSEC backend 'gssapi_spnego' registered
GENSEC backend 'gssapi_krb5' registered
GENSEC backend 'gssapi_krb5_sasl' registered
GENSEC backend 'spnego' registered
GENSEC backend 'schannel' registered
GENSEC backend 'naclrpc_as_system' registered
GENSEC backend 'sasl-EXTERNAL' registered
GENSEC backend 'ntlmssp' registered
GENSEC backend 'ntlmssp_resume_ccache' registered
GENSEC backend 'http_basic' registered
GENSEC backend 'http_ntlm' registered
GENSEC backend 'krb5' registered
GENSEC backend 'fake_gssapi_krb5' registered
Got challenge flags:
Got NTLMSSP neg_flags=0x62898215
NTLMSSP: Set final flags:
Got NTLMSSP neg_flags=0x62088215
NTLMSSP Sign/Seal – Initialising with flags:
Got NTLMSSP neg_flags=0x62088215
NTLMSSP Sign/Seal – Initialising with flags:
Got NTLMSSP neg_flags=0x62088215
Domain=[TMGRID] OS=[Windows Server 2012 R2 Standard 9600] Server=[Windows Server 2012 R2 Standard 6.3]

        Sharename       Type      Comment
        ———       —-      ——-
        ADMIN$          Disk      Remote Admin
        C$              Disk      Default share
        Files           Disk
        IPC$            IPC       Remote IPC
        MappedDrive     Disk
Connecting to 10.2.3.111 at port 139
Connecting to 10.2.3.111 at port 139
Connection to 10.2.3.111 failed (Error NT_STATUS_RESOURCE_NAME_NOT_FOUND)
NetBIOS over TCP disabled — no workgroup available

Sum it up

Lets Summarize a bit, here I described how to mount smbfs and cifs mount shares with mount command, how to define the auto mount on server boot via /etc/fstab, how to mount manually /etc/fstab defined mount and what should be the syntax of .smbcredentials user / pass file and also pointed how to debug problems on samba / windows server location share mounts with smbclient command.
 

How to remove ‘active contents’ from PDF file on Linux / Strip Active Contents from PDF

Thursday, July 18th, 2019

how-to-remove-active-content-from-pdf-with-ghoscript-on-gnu-linux.svg

I'm updating my Autiobography (CV) with my latest job eployeers, technology expertise and certifications and usually use the EuroPassCV standard web service to update already generated PDF files.The service as web based application service allows easy edit from the web as most web services which is quite handy and then allows Export to DOCX or PDF file format. So far so good but today I faced a really weird problem after, I've used successfully EuroPassCV service  and downloaded the PDF to my computer and tried to submit my Curriculum Vitae application to SAP's Successfactor newly created account for the purpose I faced a weird I error saying

"The system does not allow files with Active contents. Please …"

the-system-does-not-allow-files-with-active-contents-pdf-error-successfactors-errors

Of course if this error message was received on a Start-up application on Application upload that would be fine, but come on this is SAP's Successfactors, it cannot accept a standard generated PDF from EuroPass which nowadays is a standard for CV here in Europe and hosted on of official European Union website europa.eu

To me this is a clear signal SAP needs an experienced ICT specialists and Quality Assurance testers like me to fix their mess and I will be willing to help them if they contact me until its too late for them, but let me go back to the topic of this article which was how to remove active contents from a PDF file 🙂

So first lets make clear what is Active content in a file ?

Active contents is content that includes programs like Internet polls, JavaScript applications, stock tickers, animated images, ActiveX applications, action items, streaming video and audio, weather maps, embedded objects, and much more. Active content contains programs that trigger automatic actions on a Web page without the user's knowledge or consent.
Active contents (Macros) could exist in many file formats that are used daily in most companies / organizations daily, active content can be contained in documents such as MS Excel,  Word, PDF, PowerPoint and so on.

So why does some applications disable document support for Active contents?

Well just for the reason of security, Active contents could often be some kind of malware or crapware and they can mess up with the web application (in case of bugs) or even mess up with server software if it is a complex warm like behavior exploiting some kind of vulnerability.
One thing to say about active contents removal on file upload by applications is that this practice could only be tolerated if the organization had already adapted a security through obscurity which most likely is the case with SAP's Successfactors and many other applications out there.

So next question is how to  Panicea (Resolution) Active Contents existing in a PDF file

Assuming you have a GNU / Linux Desktop or server with ghostscript package installed (which is the case by default with virtually any modern Linux distribution), removing Active Contents from PDF to make possible file to be submitted to the picky Security Conscious application with a single command:
 

gs -dNOPAUSE -sDEVICE=pdfwrite -sOUTPUTFILE=CV-Georgi_Dimitrov_Georgiev-Europass-20190718-EN-noact-content.pdf -dBATCH CV-Georgi_Dimitrov_Georgiev-Europass-20190718-EN.pdf


After that the stripped active contents PDF file would succeed in uploading to web app.
 

Howto create Linux Music Audio CD from MP3 files / Create playable WAV format Audio CD Albums from MP3s

Tuesday, July 16th, 2019

cdburning-audio-music-cd-from-mp3-on-linuxcomapct-disc-tux-linux-logo

Recently my Mother asked me to prepare a Music Audio CD for her from a popular musician accordionist Stefan Georgiev from Dobrudja who has a unique folklore Bulgarian music.

As some of older people who still remember the age of the CD and who had most likely been into the CD burning Copy / Piracy business so popular in the countries of the ex-USSR so popular in the years 1995-2000 audio ,  Old CD Player Devices were not able to play the MP3 file format due to missing codecs (as MP3 was a proprietary compression that can't be installed on every device without paying the patent to the MP3 compression rights holder.

The revolutionary MP3 compression used to be booming standard for transferring Music data due to its high compression which made an ordinary MP3 of 5 minutes of 5MB (10+ times more compression than an ordinary classic WAV Audio the CPU intensiveness of MP3 files that puts on the reading device, requiring the CD Player to have a more powerful CPU.

Hence  due to high licensing cost and requirement for more powerful CPU enabled Audio Player many procuders of Audio Players never introduced MP3 to their devices and MP3 Neve become a standard for the Audio CD that was the standard for music listening inside almost every car out there.

Nowdays it is very rare need to create a Audio CD as audio CDs seems to be almost dead (As I heard from a Richard Stallman lecture In USA nowadays there is only 1 shop in the country where you can still buy CD or DVD drives) and only in third world as Africa Audio CDs perhaps are still in circulation.

Nomatter that as we have an old Stereo CD player on my village and perhaps many others, still have some old retired CD reading devices being able to burn out a CD is a useful thing.

Thus to make mother happy and as a learning excercise, I decided to prepare the CD for her on my Linux notebook.
Here I'll shortly describe the takes I took to make it happen which hopefully will be useful for other people that need to Convert and burn Audio CD from MP3 Album.

1. First I downloaded the Album in Mp3 format from Torrent tracker

My homeland Bulgaria and specific birth place place the city of Dobrich has been famous its folklore:  Galina Durmushlijska and Stefan Georgiev are just 2 of the many names along with Оркестър Кристал (Orchestra Crystal) and the multitude of gifted singers. My mother has a santiment for Stefan Georgiev, as she listened to this gifted accordinist on her Uncle's marriage.

Thus In my case this was (Стефан Георгиев Хора и ръченици от Добруджа) the album full song list here If you're interested to listen the Album and Enjoy unique Folklore from Dobrudja (Dobrich) my home city, Stefan Georgiev's album Hora and Rachenica Dances is available here


Stefan_Georgiev-old-audio-Music-CD-Hora-i-Rychenici-ot-Dobrudja-Horos-and-Ruchenitsas-from-Dobrudja-CD_Cover
I've downloaded them from Bulgarian famous torrent tracker zamunda.net in MP3 format.
Of course you need to have a CD / DVD readed and write device on the PC which nowdays is not present on most modern notebooks and PCs but as a last resort you can buy some cheap External Optical CD / DVD drive for 25 to 30$ from Amazon / Ebay etc.

2. You will need to install a couple of programs on Linux host (if you don't have it already)


To be able to convert from command line from MP3 to WAV you will need as minimum ffmpeg and normalize-audio packages as well as some kind of command line burning tool like cdrskin  wodim which is
the fork of old good known cdrecord, so in case if you you're wondering what happened with it just
use instead wodim.

Below is a good list of tools (assuming you have enough HDD space) to install:

root@jeremiah:/ # apt-get install –yes dvd+rw-tools cdw cdrdao audiotools growisofs cdlabelgen dvd+rw-tools k3b brasero wodim ffmpeg lame normalize-audio libavcodec58

Note that some of above packages I've installed just for other Write / Read operations for DVD drives and you might not need that but it is good to have it as some day in future you will perhaps need to write out a DVD or something.
Also the k3b here is specific to KDE and if you're a GNOME user you could use Native GNOME Desktop app such brasero or if you're in a more minimalistic Linux desktop due to hardware contrains use XFCE's native xfburn program.

If you're a console / terminal geek like me you will definitely enjoy to use cdw
 

root@jeremiah:/ # apt-cache show cdw|grep -i description -A 1
Description-en: Tool for burning CD's – console version
 Ncurses-based frontend for wodim and genisoimage. It can handle audio and

Description-md5: 77dacb1e6c00dada63762b78b9a605d5
Homepage: http://cdw.sourceforge.net/

3. Selecting preferred CD / DVD / BD program to use to write out the CD from Linux console


cdw uses wodim (which is a successor of good old known console cdrecord command most of use used on Linux in the past to burn out new Redhat / Debian / different Linux OS distro versions for upgrade purposes on Desktop and Server machines.

To check whether your CD / DVD drive is detected and ready to burn on your old PC issue:

root@jeremiah:/# wodim -checkdrive
Device was not specified. Trying to find an appropriate drive…
Detected CD-R drive: /dev/cdrw
Using /dev/cdrom of unknown capabilities
Device type    : Removable CD-ROM
Version        : 5
Response Format: 2
Capabilities   :
Vendor_info    : 'HL-DT-ST'
Identification : 'DVDRAM GT50N    '
Revision       : 'LT20'
Device seems to be: Generic mmc2 DVD-R/DVD-RW.
Using generic SCSI-3/mmc   CD-R/CD-RW driver (mmc_cdr).
Driver flags   : MMC-3 SWABAUDIO BURNFREE
Supported modes: TAO PACKET SAO SAO/R96P SAO/R96R RAW/R16 RAW/R96P RAW/R96R

You can also use xorriso (whose added value compared to other console burn cd tools is is not using external program for ISO9660 formatting neither it use an external or an external burn program for CD, DVD or BD (Blue Ray) drive but it has its own libraries incorporated from libburnia-project.org libs.

Below output is from my Thinkpad T420 notebook. If the old computer CD drive is there and still functional in most cases you should not get issues to detect it.

cdw ncurses text based CD burner tool's interface is super intuitive as you can see from below screenshot:

cdw-burn-cds-from-console-terminal-on-GNU-Linux-and-FreeBSD-old-PC-computer

CDW has many advanced abilities such as “blanking” a disk or ripping an audio CD on a selected folder. To overcome the possible problem of CDW not automatically detecting the disk you have inserted you can go to the “Configuration” menu, press F5 to enter the Hardware options and then on the first entry press enter and choose your device (by pressing enter again). Save the setting with F9.
 

4. Convert MP3 / MP4 Files or whatever format to .WAV to be ready to burn to CD


Collect all the files you want to have collected from the CD album in .MP3 a certain directory and use a small one liner loop to convert files to WAV with ffmpeg:
 

cd /disk/Music/Mp3s/Singer-Album-directory-with-MP3/

for i in $( ls *.mp3); do ffmpeg -i $i $i.wav; done


If you don't have ffmpeg installed and have mpg123 you can also do the Mp3 to WAV conversion with mpg123 cmd like so:

for i in $( ls ); do mpg123 -w $i.wav $i.mp3; done


Another alternative for conversion is to use good old lame (used to create Mp3 audio files but abling to also) decode
mp3 to wav.

lame –decode somefile.mp3 somefile.wav


In the past there was a burn command tool that was able to easily convert MP3s to WAV but in up2date Linux modern releases it is no longer available most likely due to licensing issues, for those on older Debian Linux 7 / 8 / 9 / Ubuntu 8 to 12.XX / old Fedoras etc. if you have the command you can install burn and use it (and not bother with shell loops):

apt-get install burn

or

yum install burn


Once you have it to convert

$ burn -A -a *.mp3
 

5. Fix file naming to remove empty spaces such as " " and substitute to underscores as some Old CD Players are
unable to understand spaces in file naming with another short loop.

for f in *; do mv "$f" `echo $f | tr ' ' '_'`; done

6. Normalize audio produced .WAV files (set the music volume to a certain level)


In case if wondering why normalize audio is needed here is short extract from normalize-audio man page command description to shed some light.

"normalize-audio  is  used  to  adjust  the volume of WAV or MP3 audio files to a standard volume level.  This is useful for things like creating mp3 mixes, where different recording levels on different albums can cause the volume to  vary  greatly from song to song."
 

cd /disk/Music/Mp3s/Singer-Album-directory-with-MP3/

normalize-audio -m *.wav

7. Burn the produced normalized Audio WAV files to the the CD

wodim -v -fix -eject dev='/dev/sr0' -audio -pad *.wav


Alternatively you can conver all your MP3 files to .WAV with anything be it audacity
or another program or even use 
GNOME's CDBurn tool brasero (if gnome user) or KDE's CDBurn which in my opinion is
the best CD / DVD burning application for Linux K3B.

Burning Audio CD with K3b is up to few clicks and super easy and even k3b is going to handle the MP3 to WAV file Conversion itself. To burn audio with K3B just run it and click over 'New Audio CD Project'.

k3b-on-debian-gnu-linux-burn-audio-cd-screenshot

For those who want to learn a bit more on CD / DVD / Blue-Ray burning on GNU / Linux good readings are:
Linux CD Burning Mini Howto, is Linux's CD Writing Howto on ibiblio (though a bit obsolete) or Debian's official documentation on BurnCD.
 

8. What we learned here


Though the accent of this tutorial was how to Create Audio Music CD from MP3 on GNU / Linux, the same commands are available in most FreeBSD / NetBSD / OpenBSD ports tree so you can use the same method to build prepare Audio Music CD on *BSDs.

In this article, we went through few basic ways on how to prepare WAV files from MP3 normalize the new created WAV files on Linux, to prepare files for creation of Audio Music CD for the old mom or grandma's player or even just for fun to rewind some memories. For GUI users this is easily done with  k3b,  brasero or xfburn.

I've pointed you to cdw a super useful text ncurses tool that makes CD Burninng from plain text console (on servers) without a Xorg / WayLand  GUI installed super easy. It was shortly reviewed what has changed over the last few years and why and why cdrecord was substituted for wodim. A few examples were given on how to handle conversion through bash shell loops and you were pointed to some extra reading resources to learn a bit more on the topic.
There are plenty of custom scripts around for doing the same CD Burn / Covnersion tasks, so pointing me to any external / Shell / Perl scripts is mostly welcome.

Hope this learned you something new, Enjoy ! 🙂

Upgrade Debian Linux 9 to 10 Stretch to Buster and Disable graphical service load boot on Debian 10 Linux / Debian Buster is out

Tuesday, July 9th, 2019

howto-upgrade-debian-linux-debian-stretch-to-buster-debian-10-buster

I've just took a time to upgrade my Debian 9 Stretch Linux to Debian Buster on my old school Laptop (that turned 11 years old) Lenovo Thinkpad R61 . The upgrade went more or less without severe issues except few things.

The overall procedure followed is described n a few websites out there already and comes up to;

0. Set the proper repository location in /etc/apt/sources.list


Before update the sources.list used are:
 

deb [arch=amd64,i386] http://ftp.bg.debian.org/debian/ buster main contrib non-free
deb-src [arch=amd64,i386] http://ftp.bg.debian.org/debian/ buster main contrib non-free

deb [arch=amd64,i386] http://security.debian.org/ buster/updates main contrib non-free
deb-src [arch=amd64,i386] http://security.debian.org/ buster/updates main contrib non-free

deb [arch=amd64,i386] http://ftp.bg.debian.org/debian/ buster-updates main contrib non-free
deb-src [arch=amd64,i386] http://ftp.bg.debian.org/debian/ buster-updates main contrib non-free

deb http://ftp.debian.org/debian buster-backports main


For people that had stretch defined in /etc/apt/sources.list you should change them to buster or stable, easiest and quickest way to omit editting with vim / nano etc. is run as root or via sudo:
 

sed -i 's/stretch/buster/g' /etc/apt/sources.list
sed -i 's/stretch/buster/g' /etc/apt/sources.list.d/*.list

The minimum of config in sources.list after the modification should be
 

deb http://deb.debian.org/debian buster main
deb http://deb.debian.org/debian buster-updates main
deb http://security.debian.org/debian-security buster/updates main

Or if you want to always be with latest stable packages (which is my practice for notebooks):

deb http://deb.debian.org/debian stable main
deb http://deb.debian.org/debian stable-updates main
deb http://security.debian.org/debian-security stable/updates main

1. Getting list of hold packages if such exist and unholding them, e.g.

apt-mark showhold


Same could also be done via dpkg

dpkg –get-selections | grep hold


To unhold a package if such is found:

echo "package_name install"|sudo dpkg –set-selections

For those who don't know what hold package is this is usually package you want to keep at certain version all the time even though after running apt-get upgrade to get the latest package versions.
 

2. Use df -h and assure you have at least 5 – 10 GB free space on root directory / before proceed

df -h /

3. Update packages list to set new set repos as default

apt update

4. apt upgrade
 

apt upgrade

Here some 10 – 15 times you have to confirm what you want to do with configuration that has changed if you're unsure about the config (and it is not critical service) you're aware as such as Apache / MySQL / SMTP etc. it is best to install the latest maintainer version.

Hopefully here you will not get fatal errors that will interrupt it.

P.S. It is best to run apt-update either in VTTY (Virtual console session) with screen or tmux or via a physical tty (if this is not a remote server) as during the updates your GUI access to the gnome-terminal or konsole / xterm whatever console used might get cut. Thus it is best to do it with command:
 

screen apt upgrade

5. Run dist-upgrade to finalize the upgrade from Stertch to Buster

Once all is completed of the new installed packages, you will need to finally do, once again it is best to run via screen, if you don't have installed screen install it:

if [ $(which screen) ]; then echo 'Installed'; else apt-get install –yes screen ; fi

screen apt dist-upgrade


Here once again you should set whether old configuration to some e services has to stay or the new Debian maintainer package shipped one will overwrite the old and locally modified (due to some reason), here do wisely whatever you will otherwise some configured services might not boot as expected on next boot.

6. What if you get packages failed on update


If you get a certain package failed to configure after installed due to some reason, if it is a systemd service use:

 

journalctl -xe |head -n 50


or fully observer output of journalctl -xe and decide on yourself.

In most cases

dpkg-reconfigure failed-package-name


should do the trick or at least give you more hints on how to solve it.

Also if a package seems to be in inconsistent or broken state after upgrade  and simple dpkg-reconfigure doesn't help, a good command
that can help you is

 

dpkg-reconfigure -f package_name

 

or you can try to workaround a failed package setup with:
 

dpkg –configure -a

 
If dpkg-reconfigure doesn't help either as I experienced in prior of Debian from Debian 6 -> 7 an Debian 7 ->8 updates on some Computers, then a very useful thing to try is:
 

apt-get update –fix-missing 

apt-get install -f


At certain cases the only work around to be able to complete the package upgrade is to to remove the package with apt remove but due to config errors even that is not possible to work around this as final resort run:
 

dpkg –remove –force-remove-reinstreq

 

7. Clean up ununeeded packages

Some packages are left over due to package dependencies from Stretch and not needed in buster anymore to remove them.
 

apt autoremove

 

8. Reboot system once all upgrade is over

/sbin/reboot

9. Verify your just upgraded Debian is in a good state

root@noah:~# uname -a;
Linux noah 4.19.0-5-rt-amd64 #1 SMP PREEMPT RT Debian 4.19.37-5 (2019-06-19) x86_64 GNU/Linux

 

root@noah:~# cat /etc/issue.net
Debian GNU/Linux 10
 

 

root@noah:~# lsb_release -a
No LSB modules are available.
Distributor ID:    Debian
Description:    Debian GNU/Linux 10 (buster)
Release:    10
Codename:    buster

root@noah:~# hostnamectl
   Static hostname: noah
         Icon name: computer-laptop
           Chassis: laptop
        Machine ID: 4759d9c2f20265938692146351a07929
           Boot ID: 256eb64ffa5e413b8f959f7ef43d919f
  Operating System: Debian GNU/Linux 10 (buster)
            Kernel: Linux 4.19.0-5-rt-amd64
      Architecture: x86-64

10. Remove annoying picture short animation with debian logo looping

plymouth-debian-graphical-boot-services

By default Debian 10 boots up with annoying screen hiding all the status of loaded services state .e.g. you cannot see the services that shows in [ FAILED ] state and  which do show as [ OK ] to revert back the old behavior I'm used to for historical reasons and as it shows a lot of good Boot time debugging info, in previous Debian distributions this was possible  by setting the right configuration options in /etc/default/grub

which so far in my config was like so

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash scsi_mod.use_blk_mq=y dm_mod.use_blk_mq=y zswap.enabled=1 text"


Note that zswap.enabled=1 passed option is because my notebook is pretty old machine from 2008 with 4GB of memory and zswap does accelerate performance when working with swap – especially helpful on Older PCs for more you can read more about zswap on ArchLinux wiki
After modifying this configuration to load the new config into grub the cmd is:
 

/usr/sbin/update-grub

 
As this was not working and tried number of reboots finally I found that annoying animated gif like picture shown up is caused by plymouth below is excerpts from Plymouth's manual page:


       "The plymouth sends commands to a running plymouthd. This is used during the boot process to control the display of the graphical boot splash."

Plymouth has a set of themes one can set:

 

# plymouth-set-default-theme -l
futureprototype
details
futureprototype
joy
lines
moonlight
softwaves
spacefun
text
tribar

 

I tried to change that theme to make the boot process as text boot as I'm used to historically with cmd:
 

update-alternatives –config text.plymouth

 
As after reboot I hoped the PC will start booting in text but this does not happened so the final fix to turn back to textmode service boot was to completely remove plymouth
 

apt-get remove –yes plymouth

How to start / Stop and Analyze system services and improve Linux system boot time performance

Friday, July 5th, 2019

systemd-components-systemd-utilities-targets-cores-libraries
This post is going to be a very short one and to walk through shortly to System V basic start / stop remove service old way and the new ways introduced over the last 10 years or so with the introduction of systemd on mass base across Linux distributions.
Finally I'll give you few hints on how to check (analyze) the boot time performance on a modern GNU / Linux system that is using systemd enabled services.
 

1. System V and the old days few classic used ways to stop / start / restart services (runlevels and common wrapper scripts)

The old fashioned days when Linux was using SystemV / e.g. no SystemD used way was to just go through all the running services with following the run script logic inside the runlevel the system was booting, e.g. to check runlevel and then potimize each and every run script via the respective location of the bash service init scripts:

root@noah:/home/hipo# /sbin/runlevel 
N 5

Or on some RPM based distros like Fedora / RHEL / SUSE Enterprise Linux to use chkconfig command, e.g. list services:

~]# chkconfig –list

etworkManager  0:off   1:off   2:on    3:on    4:on    5:on    6:off
abrtd           0:off   1:off   2:off   3:on    4:off   5:on    6:off
acpid           0:off   1:off   2:on    3:on    4:on    5:on    6:off
anamon          0:off   1:off   2:off   3:off   4:off   5:off   6:off
atd             0:off   1:off   2:off   3:on    4:on    5:on    6:off
auditd          0:off   1:off   2:on    3:on    4:on    5:on    6:off
avahi-daemon    0:off   1:off   2:off   3:on    4:on    5:on    6:off

And to start stop the service into (default runlevel) or respective runlevel:

~]#  chkconfig httpd on

~]# chkconfig –list httpd
httpd            0:off   1:off   2:on    3:on    4:on    5:on    6:off

~]# chkconfig service_name on –level runlevels


Debian / Ubuntu and other .deb based distributions with System V (which executes scripts without single order but one by one) are not having natively chkconfig but instead are famous for update-rc.d init script wrapper, here is few basic use  of it:

update-rc.d <service> defaults
update-rc.d <service> start 20 3 4 5
update-rc.d -f <service>  remove

Here defaults means default set boot runtime for system and numbers are just whether service is started or stopped for respective runlevels. To check what is your default one simply run /sbin/runlevel

Other useful tool to stop / start services and analyze what service is running and which not in real time (but without modifying boot time set for a service) – more universal nowadays is to use the service command.

root@noah:/home/hipo# service –status-all
 [ + ]  acpid
 [ – ]  alsa-utils
 [ – ]  anacron
 [ + ]  apache-htcacheclean
 [ – ]  apache2
 [ + ]  atd
 [ + ]  aumix

root@noah:/home/hipo# service cron restart/usr/sbin/service command is just a simple wrapper bash shell script that takes care about start / stop etc. operations of scripts found under /etc/init.d

For those who don't want to tamper with too much typing and manual configuration there is an all distribution system V compatible ncurses interface text itnerface sysv-rc-conf which could make your life easier on configuring services on non-systemd (old) Linux-es.

To install on Debian distros:

debian:~# apt-get install sysv-rc-conf

debian:~# sysv-rc-conf


SysV RC Conf desktop on GNU Linux using sysv-rc-conf systemV and systemd
 

2. SystemD basic use Start / stop check service and a little bit of information
for the novice

As most Linux kernel based distributions except some like Slackware and few others see the full list of Linux distributions without systemd (and aha yes slackw. users loves rc.local so much – we all do 🙂  migrated and are nowadays using actively SystemD, to start / stop analyze running system runnig services / processes

systemctl – Control the systemd system and service manager

To check whether a service is enabled

systemctl is-active application.service

To check whether a unit is in a failed state

systemctl is-failed application.service

To get a status of running application via systemctl messaging

# systemctl status sshd
● ssh.service – OpenBSD Secure Shell server Loaded: loaded (/lib/systemd/system/ssh.service; enabled; vendor preset: enabled) Active: active (running) since Sat 2019-07-06 20:01:02 EEST; 2h 3min ago Main PID: 1335 (sshd) Tasks: 1 (limit: 4915) CGroup: /system.slice/ssh.service └─1335 /usr/sbin/sshd -D юли 06 20:01:00 noah systemd[1]: Starting OpenBSD Secure Shell server… юли 06 20:01:02 noah sshd[1335]: Server listening on 0.0.0.0 port 22. юли 06 20:01:02 noah sshd[1335]: Server listening on :: port 22. юли 06 20:01:02 noah systemd[1]: Started OpenBSD Secure Shell server.

To enable / disable application with systemctl systemctl enable application.service

systemctl disable application.service

To stop / start given application systemcl stop sshd

systemctl stop tor

To reload running application

systemctl reload sshd

Some applications does not have the right functionality in systemd script to reload configuration without fully restarting the app if this is the case use systemctl reload-or-restart application.service

systemctl list-unit-files

Then to view the content of a single service unit file:

:~# systemctl cat apache2.service
# /lib/systemd/system/apache2.service
[Unit]
Description=The Apache HTTP Server
After=network.target remote-fs.target nss-lookup.target

[Service]
Type=forking
Environment=APACHE_STARTED_BY_SYSTEMD=true
ExecStart=/usr/sbin/apachectl start
ExecStop=/usr/sbin/apachectl stop
ExecReload=/usr/sbin/apachectl graceful
PrivateTmp=true
Restart=on-abort

[Install]
WantedBy=multi-user.target


converting-traditional-init-scripts-to-systemd-graphical-diagram

systemd's advancement over normal SystemV services it is able to track and show dependencies
of a single run service for proper operation on other services

:~# systemctl list-dependencies sshd.service


● ├─system.slice
● └─sysinit.target
●   ├─dev-hugepages.mount
●   ├─dev-mqueue.mount
●   ├─keyboard-setup.service
●   ├─kmod-static-nodes.service
●   ├─proc-sys-fs-binfmt_misc.automount
●   ├─sys-fs-fuse-connections.mount
●   ├─sys-kernel-config.mount
●   ├─sys-kernel-debug.mount
●   ├─systemd-ask-password-console.path
●   ├─systemd-binfmt.service
….

.

You can also mask / unmask service e.g. make it temporary unavailable via systemd with

sudo systemctl mask nginx.service

it will then appear as masked if you do list-unit-files

If you want to change something on a systemd unit file this is done with

systemctl edit –full nginx.service

In case if some modificatgion was done to systemd service files e.g. lets say to
/etc/systemd/system/apache2.service or even you've made a Linux system Upgrade recently
that added extra systemd service config files it will be necessery to reload all files
present in /etc/systemd/system/* with:

systemctl daemon-reload


Systemd has a target states which are pretty similar to the runlevel concept (e.g. runlevel 5 means graphical etc.), for example to check the default target for a system:

One very helpful feature is to restart systemd but it seems this is not well documented as of now and though this might work after some system package upgrade roll-outs it is always better to reboot the system, but you can give it a try if restart can't be done due to application criticallity.

To restart systemd and its spawned subprocesses do:
 

systemctl daemon-reexec

root@noah:/home/hipo# systemctl get-default
graphical.target


 to check all targets possible targets

root@noah:/home/hipo# systemctl list-unit-files –type=target
UNIT FILE                 STATE   
basic.target              static  
bluetooth.target          static  
busnames.target           static  
cryptsetup-pre.target     static  
cryptsetup.target         static  
ctrl-alt-del.target       disabled
default.target            static  
emergency.target          static  
exit.target               disabled
final.target              static  
getty.target              static  
graphical.target          static  

you can put the system in Single user mode if you like without running the good old well known command:

/sbin/init 1 

command with

systemctl rescue

You can even shutdown / poweroff / reboot system via systemctl (though I never did that and I don't recommend) 🙂
To do so use:

systemctl halt
systemctl poweroff
systemctl reboot


For the lazy ones that don't want to type all the time like crazy to configure and manage simple systemctl set services take a look at chkservice – an ncurses text based menu systemctl management interface

As chkservice is relatively new it is still not present in stable Stretch Debian repositories but it is in current testing Debian unstable Buster / Sid – Testing / Unstable distribution and has installable package for Ubuntu / Arch Linux and Fedora

chkservice-Linux-systemctl-ncurses-text-menu-service-management-interface-start-chkservice
Picture Source Tecmint.com

chkservice linux help screen


3. Analyzing and fix performance boot slowness issues due to a service taking long to boot


The first very useful thing is to know how long exactly all daemons / services got booted
on your GNU / Linux OS.

linux-server:~# systemd-analyze 
Startup finished in 4.135s (kernel) + 3min 47.863s (userspace) = 3min 51.998s

As you can see it reports both the kernel boot time and userspace (surrounding services
that had to boot for the system to be considered fully booted).


Once you have the system properly booted you have a console or / ssh access

root@pcfreak:/home/hipo# systemd-analyze blame
    2min 14.172s tor@default.service
    1min 40.455s docker.service
     1min 3.649s fail2ban.service
         58.806s nmbd.service
         53.992s rc-local.service
         51.458s systemd-tmpfiles-setup.service
         50.495s mariadb.service
         46.348s snort.service
         34.910s ModemManager.service
         33.748s squid.service
         32.226s ejabberd.service
         28.207s certbot.service
         28.104s networking.service
         23.639s munin-node.service
         20.917s smbd.service
         20.261s tinyproxy.service
         19.981s accounts-daemon.service
         18.501s loadcpufreq.service
         16.756s stunnel4.service
         15.575s oidentd.service
         15.376s dev-sda1.device
         15.368s courier-authdaemon.service
         15.301s sysstat.service
         15.154s gpm.service
         13.276s systemd-logind.service
         13.251s rsyslog.service
         13.240s lpd.service
         13.237s pppd-dns.service
         12.904s NetworkManager-wait-online.service
         12.540s lm-sensors.service
         12.525s watchdog.service
         12.515s inetd.service


As you can see you get a list of services time took to boot in secs and you can
further debug each of it to find out why it boots so slow (netwok / DNS / configuration isssue whatever).

On a servers it is useful to look up for some processes slowing it down like gdm.service etc.

Close up words rant on SystemD vs SysemV

init-and-systemd-comparison-commands-linux-booting-1

A lot could be ranted on what is better systemd or systemV. I personally hated systemd since day since I saw it being introduced first in Fedora / CentOS linuxes and a bit later in my beloved desktop used Debian Linux.
I still remember the bugs and headaches with systemd's intruduction as it is with all new the early adoption of technology makes a lot of pain in the ass.
Eventually systemd has become a standard and with my employment as a contractor through Itelligence GmBH for SAP AG I now am forced to work with systemd daily on SLES 12 based Linuces and I was forced to get used to it. 
But still there is my personal preference to SystemV even though the critics of slow boot etc.but for managing a multitude of Linux preinstalled servers like Virtual Machines and trying to standardize a Data Center with Tens of Thousands of Linuxes running on different Hypervisors VMWare / OpenXen + physical hosts etc. systemd brings a bit of more standardization that makes it a winner.