Posts Tagged ‘tmp’

Removing exim and installing qmail / Generate and install pseudo mta dummy package on Debian / Ubuntu etc. .deb based Linux

Thursday, March 10th, 2016

debian-dummy-mta-package-install-howto-tux-mail-nice-mascot
If you happen to be installing Qmail Mail server on a Debian or Ubuntu (.deb) based Linux, you will notice by default there will be some kind of MTA (Mail Transport Agent) already installed mail-transfer-agent package will be installed and because of Debian .deb package depedency to have an MTA always installed on the system you will be unable to remove Exim MTA without installing some other MTA (Postix / Qmail) etc.

This will be a problem for those like me who prefer to compile and install Qmail from source, thus to get around this it is necessery to create a dummy package that will trick the deb packaging depencies that actually mta-local MTA package is present on the server.

The way to go here is to use equivs (Circumvent debian package dependencies):
 

debian:~# apt-cache show equivs|grep -i desc -A 10

Description: Circumvent Debian package dependencies
 This package provides a tool to create trivial Debian packages.
 Typically these packages contain only dependency information, but they
 can also include normal installed files like other packages do.
 .
 One use for this is to create a metapackage: a package whose sole
 purpose is to declare dependencies and conflicts on other packages so
 that these will be automatically installed, upgraded, or removed.
 .
 Another use is to circumvent dependency checking: by letting dpkg
 think a particular package name and version is installed when it

Btw creating a .deb dummy package will be necessery in many other cases when you have to install from some third party debian repositories or some old and alrady unmaintaned deb-src packages for the sake of making some archaic software to resurrect somewhere, so sooner or later even if you're not into Mail servers you will certainly need equivs.

Then install equivs and go on proceeding creating the dummy mail-transport-agent package
 

debian:~# cd /tmp debian:~# cp -rpf /usr/share/doc/equivs/examples/mail-transport-agent.ctl . debian:~# equivs-build mail-transport-agent.ctl


Above command will build and package /tmp/mta-local_1.0_all.deb dummy package.
So continue and install it with dpkg as you use to install debian packages
 

 

debian:~# dpkg -i /tmp/mta-local_1.0_all.deb


From then on you can continue your standard LWQ – Life with Qmail or any other source based qmail installation with:

 

 

./config-fast mail.yourmaildomain.net


So that's it now .deb packaging system consistency will be complete so standard security package updates with apt-get and aptitude updates or dpkg -i third party custom software insatlls will not be breaking up any more.

Hope that helped someone 🙂

 

 

 

 

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Adding Listing and Deleting SSL Certificates in keystore Tomcat Application server / What is keystore

Thursday, December 5th, 2013

Apache Tomcat keystore delete import list logo

 I work on ongoing project where Tomtat Application servers configured to run Clustered located behind Apache with mod_proxy configured to use ReverseProxy are used. One of customers which required a java application deployment experienced issues with application's capability to connect to SAP database.

After some investigation I figured out, the application is unable to connect to the SAP db server becuse remote host webserver running some SAP related stuff was not connecting due to expired certificate in Tomcat Keystore known also as JKS / Java Keystore– (.keystore) – which is a file containing multiple remote hosts imported certificates.

The best and shortest definition of keystore is:

Keystore entry = private + public key pair = identified by an alias

The keystore protects each private key with its individual password, and also protects the integrity of the entire keystore with a (possibly different) password.

Managing Java imported certificates later used by Tomcat is done with a command line tool part of JDK (Java Development Kit) called keystore. Keystore is usually located under /opt/java/jdk/bin/keytool. My Java VM is installed in /opt/ anyways usual location of keytool is $JAVA_HOME/bin/

Keytool has capabilities to create / modify / delete or import new SSL certificates and then Java applications can access remote applications which requires Secure Socket Layer handshake . Each certificate kept in .keystore file (usually located somewhere under Tomcat web app server directory tree), lets say – /opt/tomcat/current/conf/.keystore

1. List current existing imported SSL certificates into Java's Virtual Machine

tomcat-server:~# /opt/java/jdk/bin/keytool -list -keystore /opt/tomcat/current/conf/.keystore
password:
Command returns output similar to;

Entry type: trustedCertEntry

Owner: CN=www.yourhost.com, OU=MEMBER OF E.ON GROUP, OU=DEVICES, O=E.GP AG, C=DE
Issuer: CN=E.ON Internal Devices Sub CA V2, OU=CA, O=EGP, C=DE
Serial number: 67460001001c6aa51fd25c0e8320
Valid from: Mon Dec 27 07:05:33 GMT 2010 until: Fri Dec 27 07:05:22 GMT 2013
Certificate fingerprints:
         MD5:  D1:AA:D5:A9:A3:D2:95:28:F1:79:57:25:D3:6A:16:5E
         SHA1: 73:CE:ED:EC:CA:18:E4:E4:2E:AA:25:58:E0:2B:E4:D4:E7:6E:AD:BF
         Signature algorithm name: SHA1withRSA
         Version: 3

Extensions:

#1: ObjectId: 2.5.29.15 Criticality=true
KeyUsage [
  DigitalSignature
  Key_Encipherment
  Key_Agreement
]

#2: ObjectId: 2.5.29.19 Criticality=true
BasicConstraints:[
  CA:false
  PathLen: undefined
]

#3: ObjectId: 1.3.6.1.5.5.7.1.1 Criticality=false
AuthorityInfoAccess [
  [
   accessMethod: 1.3.6.1.5.5.7.48.2
   accessLocation: URIName: http://yourhost.com/cacerts/egp_internal_devices_sub_ca_v2.crt,
   accessMethod: 1.3.6.1.5.5.7.48.2
   accessLocation: URIName: http://www.yourhost1.com/certservices/cacerts/egp_internal_devices_sub_ca_v2.crt]
]

#4: ObjectId: 2.5.29.14 Criticality=false
SubjectKeyIdentifier [
KeyIdentifier [
0000: D3 52 C7 63 0F 98 BF 6E   FE 00 56 5C DF 35 62 22  .R.c…n..V\.5b"
0010: F2 B9 5B 8F                                        ..[.
]

Note that password that will be promtped has is by default changeit (in case if you don't have explicitly changed it from Tomcat's default config server.xml).

2. Delete Old expired SSL host Certificate from Java Keystore
It is good practice to always make backup of old .keystore before modifying, so I ran:

tomcat-server:~# cp -rpf /opt/tomcat/current/conf/.keystore /opt/tomcat/current/conf/.keystore-05-12-2013

In my case first I had to delete old expired SSL certificate with:

tomcat-server:~# /opt/java/jdk/bin/keytool -delete -alias "your-hostname" -v -keystore /opt/tomcat/current/conf/.keystore

Then to check certificate is no longer existent in keystore chain;
tomcat-server:~# /opt/java/jdk/bin/keytool -list -keystore /opt/tomcat/current/conf/.keystore

-keystore – option is obligitory it does specify where keystore file is located
-list – does list the certificate
-v – stands for verbose

 

3. Finally to import new SSL from already expored via a browser url in keystore

tomcat-server:~# /opt/java/jdk/bin/keytool -importcert -file /tmp/your-hostname.cer -alias your-hostname.com -keystore /opt/tomcat/current/conf/.keystore

More complete information on how to deal with keystore is available from Apache Tomcat's SSL Howto – a must read documentation for anyone managing Tomcat.

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How to solve “Incorrect key file for table ‘/tmp/#sql_9315.MYI’; try to repair it” mysql start up error

Saturday, April 28th, 2012

When a server hard disk scape gets filled its common that Apache returns empty (no content) pages…
This just happened in one server I administer. To restore the normal server operation I freed some space by deleting old obsolete backups.
Actually the whole reasons for this mess was an enormous backup files, which on the last monthly backup overfilled the disk empty space.

Though, I freed about 400GB of space on the the root filesystem and on a first glimpse the system had plenty of free hard drive space, still restarting the MySQL server refused to start up properly and spit error:

Incorrect key file for table '/tmp/#sql_9315.MYI'; try to repair it" mysql start up error

Besides that there have been corrupted (crashed) tables, which reported next to above error.
Checking in /tmp/#sql_9315.MYI, I couldn't see any MYI – (MyISAM) format file. A quick google look up revealed that this error is caused by not enough disk space. This was puzzling as I can see both /var and / partitions had plenty of space so this shouldn't be a problem. Also manally creating the file /tmp/#sql_9315.MYI with:

server:~# touch /tmp/#sql_9315.MYI

Didn't help it, though the file created fine. Anyways a bit of a closer examination I've noticed a /tmp filesystem mounted besides with the other file system mounts ????
You can guess my great amazement to find this 1 Megabyte only /tmp filesystem hanging on the server mounted on the server.

I didn't mounted this 1 Megabyte filesystem, so it was either an intruder or some kind of "weird" bug…
I digged in Googling to see, if I can find more on the error and found actually the whole mess with this 1 mb mounted /tmp partition is caused by, just recently introduced Debian init script /etc/init.d/mountoverflowtmp.
It seems this script was introduced in Debian newer releases. mountoverflowtmp is some kind of emergency script, which is triggered in case if the root filesystem/ space gets filled.
The script has only two options:

# /etc/init.d/mountoverflowtmp
Usage: mountoverflowtmp [start|stop]

Once started what it does it remounts the /tmp to be 1 megabyte in size and stops its execution like it never run. Well maybe, the developers had something in mind with introducing this script I will not argue. What I should complain though is the script design is completely broken. Once the script gets "activated" and does its job. This 1MB mount stays like this, even if hard disk space is freed on the root partition – / ….

Hence to cope with this unhandy situation, once I had freed disk space on the root partition for some reason mountoverflowtmp stop option was not working,
So I had to initiate "hard" unmount:

server:~# mount -l /tmp

Also as I had a bunch of crashed tables and to fix them, also issued on each of the broken tables reported on /etc/init.d/mysql start start-up.

server:~# mysql -u root -p
mysql> use Database_Name;
mysql> repair table Table_Name extended;
....

Then to finally solve the stupid Incorrect key file for table '/tmp/#sql_XXYYZZ33444.MYI'; try to repair it error, I had to restart once again the SQL server:

Stopping MySQL database server: mysqld.
Starting MySQL database server: mysqld.
Checking for corrupt, not cleanly closed and upgrade needing tables..
root@server:/etc/init.d#

Tadadadadam!, SQL now loads and works back as before!

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How to delete million of files on busy Linux servers (Work out Argument list too long)

Tuesday, March 20th, 2012

How to Delete million or many thousands of files in the same directory on GNU / Linux and FreeBSD

If you try to delete more than 131072 of files on Linux with rm -f *, where the files are all stored in the same directory, you will get an error:

/bin/rm: Argument list too long.

I've earlier blogged on deleting multiple files on Linux and FreeBSD and this is not my first time facing this error.
Anyways, as time passed, I've found few other new ways to delete large multitudes of files from a server.

In this article, I will explain shortly few approaches to delete few million of obsolete files to clean some space on your server.
Here are 3 methods to use to clean your tons of junk files.

1. Using Linux find command to wipe out millions of files

a.) Finding and deleting files using find's -exec switch:

# find . -type f -exec rm -fv {} \;

This method works fine but it has 1 downside, file deletion is too slow as for each found file external rm command is invoked.

For half a million of files or more, using this method will take "long". However from a server hard disk stressing point of view it is not so bad as, the files deletion is not putting too much strain on the server hard disk.
b.) Finding and deleting big number of files with find's -delete argument:

Luckily, there is a better way to delete the files, by using find's command embedded -delete argument:

# find . -type f -print -delete

c.) Deleting and printing out deleted files with find's -print arg

If you would like to output on your terminal, what files find is deleting in "real time" add -print:

# find . -type f -print -delete

To prevent your server hard disk from being stressed and hence save your self from server normal operation "outages", it is good to combine find command with ionice, e.g.:

# ionice -c 3 find . -type f -print -delete

Just note, that ionice cannot guarantee find's opeartions will not affect severely hard disk i/o requests. On  heavily busy servers with high amounts of disk i/o writes still applying the ionice will not prevent the server from being hanged! Be sure to always keep an eye on the server, while deleting the files nomatter with or without ionice. if throughout find execution, the server gets lagged in serving its ordinary client requests or whatever, stop the execution of the cmd immediately by killing it from another ssh session or tty (if physically on the server).

2. Using a simple bash loop with rm command to delete "tons" of files

An alternative way is to use a bash loop, to print each of the files in the directory and issue /bin/rm on each of the loop elements (files) like so:

for i in *; do
rm -f $i;
done

If you'd like to print what you will be deleting add an echo to the loop:

# for i in $(echo *); do \
echo "Deleting : $i"; rm -f $i; \

The bash loop, worked like a charm in my case so I really warmly recommend this method, whenever you need to delete more than 500 000+ files in a directory.

3. Deleting multiple files with perl

Deleting multiple files with perl is not a bad idea at all.
Here is a perl one liner, to delete all files contained within a directory:

# perl -e 'for(<*>){((stat)[9]<(unlink))}'

If you prefer to use more human readable perl script to delete a multitide of files use delete_multple_files_in_dir_perl.pl

Using perl interpreter to delete thousand of files is quick, really, really quick.
I did not benchmark it on the server, how quick exactly is it, but I guess the delete rate should be similar to find command. Its possible even in some cases the perl loop is  quicker …

4. Using PHP script to delete a multiple files

Using a short php script to delete files file by file in a loop similar to above bash script is another option.
To do deletion  with PHP, use this little PHP script:

<?php
$dir = "/path/to/dir/with/files";
$dh = opendir( $dir);
$i = 0;
while (($file = readdir($dh)) !== false) {
$file = "$dir/$file";
if (is_file( $file)) {
unlink( $file);
if (!(++$i % 1000)) {
echo "$i files removed\n";
}
}
}
?>

As you see the script reads the $dir defined directory and loops through it, opening file by file and doing a delete for each of its loop elements.
You should already know PHP is slow, so this method is only useful if you have to delete many thousands of files on a shared hosting server with no (ssh) shell access.

This php script is taken from Steve Kamerman's blog . I would like also to express my big gratitude to Steve for writting such a wonderful post. His post actually become  inspiration for this article to become reality.

You can also download the php delete million of files script sample here

To use it rename delete_millioon_of_files_in_a_dir.php.txt to delete_millioon_of_files_in_a_dir.php and run it through a browser .

Note that you might need to run it multiple times, cause many shared hosting servers are configured to exit a php script which keeps running for too long.
Alternatively the script can be run through shell with PHP cli:

php -l delete_millioon_of_files_in_a_dir.php.txt.

5. So What is the "best" way to delete million of files on Linux?

In order to find out which method is quicker in terms of execution time I did a home brew benchmarking on my thinkpad notebook.

a) Creating 509072 of sample files.

Again, I used bash loop to create many thousands of files in order to benchmark.
I didn't wanted to put this load on a productive server and hence I used my own notebook to conduct the benchmarks. As my notebook is not a server the benchmarks might be partially incorrect, however I believe still .they're pretty good indicator on which deletion method would be better.

hipo@noah:~$ mkdir /tmp/test
hipo@noah:~$ cd /tmp/test;
hiponoah:/tmp/test$ for i in $(seq 1 509072); do echo aaaa >> $i.txt; done

I had to wait few minutes until I have at hand 509072  of files created. Each of the files as you can read is containing the sample "aaaa" string.

b) Calculating the number of files in the directory

Once the command was completed to make sure all the 509072 were existing, I used a find + wc cmd to calculate the directory contained number of files:

hipo@noah:/tmp/test$ find . -maxdepth 1 -type f |wc -l
509072

real 0m1.886s
user 0m0.440s
sys 0m1.332s

Its intesrsting, using an ls command to calculate the files is less efficient than using find:

hipo@noah:/tmp/test$ time ls -1 |wc -l
509072

real 0m3.355s
user 0m2.696s
sys 0m0.528s

c) benchmarking the different file deleting methods with time

– Testing delete speed of find

hipo@noah:/tmp/test$ time find . -maxdepth 1 -type f -delete
real 15m40.853s
user 0m0.908s
sys 0m22.357s

You see, using find to delete the files is not either too slow nor light quick.

– How fast is perl loop in multitude file deletion ?

hipo@noah:/tmp/test$ time perl -e 'for(<*>){((stat)[9]<(unlink))}'real 6m24.669suser 0m2.980ssys 0m22.673s

Deleting my sample 509072 took 6 mins and 24 secs. This is about 3 times faster than find! GO-GO perl 🙂
As you can see from the results, perl is a great and time saving, way to delete 500 000 files.

– The approximate speed deletion rate of of for + rm bash loop

hipo@noah:/tmp/test$ time for i in *; do rm -f $i; done

real 206m15.081s
user 2m38.954s
sys 195m38.182s

You see the execution took 195m en 38 secs = 3 HOURS and 43 MINUTES!!!! This is extremely slow ! But works like a charm as the running of deletion didn't impacted my normal laptop browsing. While the script was running I was mostly browsing through few not so heavy (non flash) websites and doing some other stuff in gnome-terminal) 🙂

As you can imagine running a bash loop is a bit CPU intensive, but puts less stress on the hard disk read/write operations. Therefore its clear using it is always a good practice when deletion of many files on a dedi servers is required.

b) my production server file deleting experience

On a production server I only tested two of all the listed methods to delete my files. The production server, where I tested is running Debian GNU / Linux Squeeze 6.0.3. There I had a task to delete few million of files.
The tested methods tried on the server were:

– The find . type -f -delete method.

– for i in *; do rm -f $i; done

The results from using find -delete method was quite sad, as the server almost hanged under the heavy hard disk load the command produced.

With the for script all went smoothly. The files were deleted for a long long time (like few hours), but while it was running, the server continued with no interruptions..

While the bash loop was running, the server load avarage kept at steady 4
Taking my experience in mind, If you're running a production, server and you're still wondering which delete method to use to wipe some multitude of files, I would recommend you go  the bash for loop + /bin/rm way. Yes, it is extremely slow, expect it run for some half an hour or so but puts not too much extra load on the server..

Using the PHP script will probably be slow and inefficient, if compared to both find and the a bash loop.. I didn't give it a try yet, but suppose it will be either equal in time or at least few times slower than bash.

If you have tried the php script and you have some observations, please drop some comment to tell me how it performs.

To sum it up;

Even though there are "hacks" to clean up some messy parsing directory full of few million of junk files, having such a directory should never exist on the first place.

Frankly, keeping millions of files within the same directory is very stupid idea.
Doing so will have a severe negative impact on a directory listing performance of your filesystem in the long term.

If you know better (more efficient) ways to delete a multitude of files in a dir please share in comments.

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How to disable tidy HTML corrector and validator to output error and warning messages

Sunday, March 18th, 2012

I've noticed in /var/log/apache2/error.log on one of the Debian servers I manage a lot of warnings and errors produced by tidy HTML syntax checker and reformatter program.

There were actually quite plenty frequently appearing messages in the the log like:

...
To learn more about HTML Tidy see http://tidy.sourceforge.net
Please fill bug reports and queries using the "tracker" on the Tidy web site.
Additionally, questions can be sent to html-tidy@w3.org
HTML and CSS specifications are available from http://www.w3.org/
Lobby your company to join W3C, see http://www.w3.org/Consortium
line 1 column 1 - Warning: missing <!DOCTYPE> declaration
line 1 column 1 - Warning: plain text isn't allowed in <head> elements
line 1 column 1 - Info: <head> previously mentioned
line 1 column 1 - Warning: inserting implicit <body>
line 1 column 1 - Warning: inserting missing 'title' element
Info: Document content looks like HTML 3.2
4 warnings, 0 errors were found!
...

I did a quick investigation on where from this messages are logged in error.log, and discovered few .php scripts in one of the websites containing the tidy string.
I used Linux find + grep cmds find in all php files the "tidy "string, like so:

server:~# find . -iname '*.php'-exec grep -rli 'tidy' '{}' ;
find . -iname '*.php' -exec grep -rli 'tidy' '{}' ; ./new_design/modules/index.mod.php
./modules/index.mod.php
./modules/index_1.mod.php
./modules/index1.mod.php

Opening the files, with vim to check about how tidy is invoked, revealed tidy calls like:

exec('/usr/bin/tidy -e -ashtml -utf8 '.$tmp_name,$rett);

As you see the PHP programmers who wrote this website, made a bigtidy mess. Instead of using php5's tidy module, they hard coded tidy external command to be invoked via php's exec(); external tidy command invocation.
This is extremely bad practice, since it spawns the command via a pseudo limited apache shell.
I've notified about the issue, but I don't know when, the external tidy calls will be rewritten.

Until the external tidy invocations are rewritten to use the php tidy module, I decided to at least remove the tidy warnings and errors output.

To remove the warning and error messages I've changed:

exec('/usr/bin/tidy -e -ashtml -utf8 '.$tmp_name,$rett);

exec('/usr/bin/tidy --show-warnings no --show-errors no -q -e -ashtml -utf8 '.$tmp_name,$rett);

The extra switches meaning is like so:

q – instructs tidy to produce quiet output
-e – show only errors and warnings
–show warnings no && –show errors no, completely disable warnings and error output

Onwards tidy no longer logs junk messages in error.log Not logging all this useless warnings and errors has positive effect on overall server performance especially, when the scripts, running /usr/bin/tidy are called as frequently as 1000 times per sec. or more

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How to add repository manually from command line in Ubuntu Linux

Sunday, January 8th, 2012

I'm on a way trying to install Free Mega Games Pack and I'm facing troubles in following the instructions to add a the latest development wine version described on http://www.winehq.org/download/ubuntu
The guys from WineHQ has to update the wine install instructions, since the instructions are targetting older versions of Ubuntu which are not compatible with newer Ubuntus which comes natively with Unity
In order to complete the step in adding the WineHQ Ubuntu PPA development repository my only way was to add it using command line.
Here is how:

root@ubuntu:~# apt-add-repository ppa:ubuntu-wine/ppa
You are about to add the following PPA to your system:
Latest official WineHQ releases
Welcome to the Wine Team PPA. Here you can get the latest available Wine betas for every supported version of Ubuntu. This PPA is managed by Scott Ritchie, and is a replacement for the WineHQ budgetdedicated.com repository used for Jaunty and earlier.
More info: https://launchpad.net/~ubuntu-wine/+archive/ppa
Press [ENTER] to continue or ctrl-c to cancel adding it
Executing: gpg --ignore-time-conflict --no-options --no-default-keyring --secret-keyring /tmp/tmp.bvo21sFWKG --trustdb-name /etc/apt/trustdb.gpg --keyring /etc/apt/trusted.gpg --primary-keyring /etc/apt/trusted.gpg --keyserver hkp://keyserver.ubuntu.com:80/ --recv 883E8688397576B6C509DF495A9A06AEF9CB8DB0
gpg: requesting key F9CB8DB0 from hkp server keyserver.ubuntu.com
gpg: key F9CB8DB0: public key "Launchpad PPA for Ubuntu Wine Team" imported
gpg: no ultimately trusted keys found
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)

Similarly adding a PPA repository on Debian is also possible by using a little shell script add-apt-repository.sh . add-apt-repository.sh simulates what ubuntu's apt-add-repositry python script does.

It is educative to mention PPA stands for (Personal package Archive) and the difference between normal repository and PPA is mainly in the fact that PPA repositories makes a package distributed by the repository like the native Ubuntu packages issued by Canonical.
Once for example a new version of a file is placed in PPA deb package repository, the newer package will be automatically installed to the system using it.

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Where does Debian GNU / Linux Apache + PHP stores session files?

Tuesday, November 22nd, 2011

In order to debug some PHP session problems on Debian, I needed to check the count of existing session files.
When PHP is compiled from source usually, by default sessions are stored in /tmp directory, however this is not the case on Debian.

Debian’s PHP session directory is different, there the sessions are stored in the directory:

/var/lib/php5

I’ve discovered the session directory location by reading Debian’s cron shell script, which delete session files on every 30 minutes.

Here is the file content:

debian~# cat /etc/cron.d/php5
# /etc/cron.d/php5: crontab fragment for php5
# This purges session files older than X, where X is defined in seconds
# as the largest value of session.gc_maxlifetime from all your php.ini
# files, or 24 minutes if not defined. See /usr/lib/php5/maxlifetime

# Look for and purge old sessions every 30 minutes
09,39 * * * * root [ -x /usr/lib/php5/maxlifetime ] &&
[ -d /var/lib/php5 ] && find /var/lib/php5/ -type f -cmin +$(/usr/lib/php5/maxlifetime) -delete

To check the amount of existing PHP opened session files:

debian:~# ls -1 /var/lib/php5|wc -l
14049

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How to copy CD or DVD on GNU/Linux and FreeBSD using console or terminal

Monday, November 14th, 2011

CD Burning Console Terminal Linux / FreeBSD picture

These days more and more people start to forget the g* / Linux old times when we used to copy CDs from console using dd in conjunction with mkisofs .

Therefore to bring some good memories back of the glorious console times I decided to come up with this little post.

To copy a CD or DVD the first thing one should do is to make an image copy of the present inserted CD into the CD-drive with dd :

1. Make copy of the CD/DVD image using dd

# dd if=/dev/cdrom of=/tmp/mycd.iso bs=2048 conv=notrunc

/dev/cdrom is the location of the cdrom device, on many Linuces including (Debian) /dev/cdrom is just a link to the /dev/ which corresponds to the CD drive. Note on FreeBSD the location for the CD Drive is /dev/acd0
/tmp/mycd.iso instructs dd CD image creation to be placed in /tmp/ directory.
bs argument instructs it about the byte size portions by which the content of the CD-Drive inserted CD will be read. bs value of 2048 is actually only 2KB per dd read, increasing this value will decrease the time required for the CD image to be extracted.

2. Prepare CD image file to be ready for burning

After dd completes the image copy operation, next to prepare the extracted image / ISO to be ready for burning mkisofs is used:

# mkisofs -J -L -r -V TITLE -o /tmp/imagefile.iso /tmp/mycd.iso

The -J option makes the CD compatible for Pcs running Microsoft Windows. The -V TITLE option should be changed to whatever title the new CD should have, -r will add up status bar for the mkisofs operation.
-r is passed to create specific file permissions on the newly created CD, -o specifies the location where mkisofs will produce its file based on the CD image /tmp/mycd.iso .

3. Burning the mkisofs image file to a CD/DVD on GNU / Linux

linux:~# cdrecord -scanbus
linux:~# cdrecord dev=1,0,0 /tmp/imagefile.iso

If all wents okay with cdrecord operation, after a while the CD should be ready.

4. Burning the mkisofs image file to CD on FreeBSD

freebsd# burncd -f /dev/acd0 data /tmp/imagefile.iso fixate

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