The Linux Way of youtube to mp3
Few days ago, I found a new song in youtube and I've been listening it since then. I like to have it in my mp3 player but I couldn't find it in mp3 format. First, I thought to google it for tools or add-ons to convert from youtube video to mp3 but then I realized that it is actually quite easy with the shell. The necessary processes are already in place in my Linux.
1. youtube-dl, is a small command-line program to download videos from YouTube.com and a few more sites.
2. ffmpeg, is a complete, cross-platform solution to record, convert and stream audio and video.
3. lame, is a high quality MPEG Audio Layer III (MP3) encoder licensed under the LGPL.
Here is the procedure;
First download the video with youtube-dl
$ youtube-dl "http://www.youtube.com/watch?v=QjA5faZF1A8"
then extract the audio from the video file with ffmpeg
$ ffmpeg -i QjA5faZF1A8.flv QjA5faZF1A8.wav
last, convert the wav file to mp3 with lame
$ lame QjA5faZF1A8.wav QjA5faZF1A8.mp3
Enjoy it 
ThinkPad x100e and Fedora 13
I've been running Fedora 12 with x100e since April. I had written about the Fedora 12 installation here. I decided to install Fedora 13 last week. I think Fedora 13 installation is smoother than Fedora 12 installation. In addition, I've been more satisfied with Fedora 13 performance so far.
Installation consists 3 steps,
1. Put your Fedora 13 DVD to your driver and boot up from DVD drive. Follow the installation steps and install Fedora 13. I performed the installation with external DVD driver. There is no trick in the first step, it's similar to any other simple installation.
2. During the first boot after installation, Fedora 13 freezes. You need to edit kernel parameters as following. At Grub prompt, press 'e' to edit the command before booting, then select the second line and again press 'e' to edit the selected command. Type radeon.modeset=0 at the end of the command, press 'b' to boot up. This is the way to boot up Fedora 13 until display driver installation.
3. Install the ATI display driver and wireless adapter driver.
a. ATI Display Driver link (Notebook Graphics -> Mobility Radeon Series -> Mobility Radeon HD 3xxx Series -> Linux x86).
b. You need to get wireless adapter driver from Realtek website and build it (to install compiler and other development packages as prerequisite). The RTL8192SE driver works well in my system, even wireless adapter is reported as 8172 in lspci output.
Now, you can boot up without radeon.modeset=0.
Display
ThinkPad x100e and Fedora 12
I had installed the Fedora 12 via external DVD driver, I hadn't faced any problem during the installation. However, Fedora freezes on the first boot. I can make it boot by disabling ACPI in Grub.
At Grub prompt press 'e' to edit the command before booting, then select the second line and again press 'e' to edit selected command. Type acpi=off at the end of the command, press 'b' to start the boot procedure.
After I successfully boot up the Fedora, I updated the system. Unfortunately, the ACPI problem hasn't been solved by updates. I added acpi=off to the grub.conf file under /boot/grub/grub.conf to make it permanent (run grub-install after editing grub.conf file, like grub-install /dev/sda). Disabling ACPI isn't very good idea, especially in a laptop. As I found on the net, Ubuntu works fine when acpi=on. I am going to try finding better Fedora solution later. I think it is enough to get it work today.
The wireless adapter driver isn't supported on default. You need to get it from Realtek website and build it (to install compiler and other development packages as prerequisite). The RTL8192SE driver works well in my system, even wireless adapter is reported as 8172 in lspci output.
Finally, I typed the commands to getting the scroll button work as follows;
> yum install gpointing-device-settings.i686 > gpointing-device-settings
- Select TPPS/2 IBM TrackPoint, check "Use wheel emulation" and set 2 as button value (not permanent!).
Note: After I wrote the explanation above, I found another way to run Fedora on x100e. I patched and compiled the kernel. I run the Fedora without acpi=off now. I sent the patch to other two users and they reported that it works fine on their x100e as well. Please write me if you need the patch.
Linux RAM-Based Filesystem
I have been searching the Internet for the RAM-based filesystem in Linux. There are many posts and each one describes its solution and configuration well. However, after reading few of them, it may seem a little confusing because there are 3 different mechanisms -ramdisk, ramfs and tmpfs- to create a RAM-based filesystem in Linux and current posts generally describes and compares one or two. In addition, there is a name confusion, some posts used 'ramdisk' as a general name. RAM-based filesystem is more commonly known as ramdisk. However, one of the Linux mechanisms is also called as ramdisk. Therefore, I always use the word 'ramdisk' to indicate the Linux mechanism rather than general name throughout the post.
I like to describe all mechanisms and compare them as well. However there are some details you may not want to know if you like to just use it rather than to care how the Linux kernel handles it inside. That's why I don't mention all details here and keep it as simple as possible. If you like to know all details, the Linux kernel documentation files filesystems/ramfs-rootfs-initramfs.txt and filesystems/tmpfs.txt are the right places to start and then of course the Linux kernel source code itself for the definite guide.
I assume you already know what the RAM-based filesystem and for what purpose it has been used. I skip the introductory information. In addition, I assume you have got some Linux background (grub, mount, shell etc.).
I have been using Fedora 12 for the configuration examples, I expect, the examples work with other GNU/Linux distributions running 2.6.x kernels (compiled with ramdisk support).
1 - ramdisk
The ramdisk is the oldest mechanism to create RAM-based filesystem in Linux. Basically, it is a way to use the system memory as a block device. This block device is fixed size and it needs a filesystem driver such as ext2 (It is possible to create ext3 filesystem on ramdisk. However, it doesn't make sense since we don't need journal on RAM-based filesystem). The ramdisk run similar to other block devices, it means ramdisk uses Linux's file caching mechanism similar to other block devices. Consequently, the ramdisk wastes memory and CPU time compare to ramfs and tmpfs because it caches the data that already in memory.
Fedora 12 has got 16 ramdisks as default (at least mine does), the default size of the ramdisks is 16MB. If you like to increase the size of the ramdisks, you must pass a parameter -'ramdisk_size=X'- to kernel during boot. I increased to 64MB in my environment, the related grub.conf file line is below
kernel /boot/vmlinuz-2.6.31.12-174.2.22.fc12.x86_64 ro root=UUID=a2142f4e-7880-4419-9051-0433bdc36277 ramdisk_size=65536 rhgb quiet
and here is the list of default ramdisks. These ramdisks don't use any memory area until you format them and mount.
[root@localhost /]# ls -l /dev/ram* brw-rw---- 1 root disk 1, 0 2010-03-04 03:44 /dev/ram0 brw-rw---- 1 root disk 1, 1 2010-03-04 03:44 /dev/ram1 brw-rw---- 1 root disk 1, 10 2010-03-04 03:44 /dev/ram10 brw-rw---- 1 root disk 1, 11 2010-03-04 03:44 /dev/ram11 brw-rw---- 1 root disk 1, 12 2010-03-04 03:44 /dev/ram12 brw-rw---- 1 root disk 1, 13 2010-03-04 03:44 /dev/ram13 brw-rw---- 1 root disk 1, 14 2010-03-04 03:44 /dev/ram14 brw-rw---- 1 root disk 1, 15 2010-03-04 03:44 /dev/ram15 brw-rw---- 1 root disk 1, 2 2010-03-04 03:44 /dev/ram2 brw-rw---- 1 root disk 1, 3 2010-03-04 03:44 /dev/ram3 brw-rw---- 1 root disk 1, 4 2010-03-04 03:44 /dev/ram4 brw-rw---- 1 root disk 1, 5 2010-03-04 03:44 /dev/ram5 brw-rw---- 1 root disk 1, 6 2010-03-04 03:44 /dev/ram6 brw-rw---- 1 root disk 1, 7 2010-03-04 03:44 /dev/ram7 brw-rw---- 1 root disk 1, 8 2010-03-04 03:44 /dev/ram8 brw-rw---- 1 root disk 1, 9 2010-03-04 03:44 /dev/ram9
Now, we can create the file system; in other words, format the ramdisk.
[root@localhost /]# mke2fs -t ext2 -m 0 /dev/ram0
mke2fs 1.41.9 (22-Aug-2009)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
16384 inodes, 65536 blocks
0 blocks (0.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=67108864
8 block groups
8192 blocks per group, 8192 fragments per group
2048 inodes per group
Superblock backups stored on blocks:
8193, 24577, 40961, 57345
Writing inode tables: done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 21 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
Then, create the mount point, mount and verify.
[root@localhost /]# mkdir /tmp/ramdisk [root@localhost /]# mount /dev/ram0 /tmp/ramdisk [root@localhost /]# df -h | grep ramdisk /dev/ram0 62M 1.3M 61M 3% /tmp/ramdisk [root@localhost /]# mount | grep ramdisk /dev/ram0 on /tmp/ramdisk type ext2 (rw)
If you need to ramdisk on every boot up, you should do some scripting.
2 - ramfs
The ramfs is a very simple filesystem. It turns Linux's disk caching mechanisms into dynamically resizable RAM-based filesystem. Linux caches all files. Files read from device are kept in memory since they're likely to be needed again and they're set as clean to free in case virtual memory system needs the memory. Similarly, data written to files are kept in memory and set as clean as soon as they've been written to device. However, ramfs hasn't got any device to write back. Files written to ramfs allocate cache structures as usual but there is nowhere to write them back. It means the cache never set as clean.
One downside of ramfs is you can not set size limit. Therefore you can keep writing to ramfs until you fill up all memory. The virtual memory system can't free it (can't move to swap space). That's why you should be very careful if you decide to chose ramfs. In addition, you should carefully set the permissions to identify which users are allowed to write the ramfs. I think no one likes to freeze the system.
Configuring ramfs is very easy compare to ramdisk, we only need to create the mount point and mount it.
[root@localhost /]# mkdir /tmp/ramfs [root@localhost /]# mount -t ramfs ramfs /tmp/ramfs [root@localhost /]# mount | grep ramfs ramfs on /tmp/ramfs type ramfs (rw) [root@localhost /]# df -h | grep ramfs [root@localhost /]#
It is ready to use (you can not see it in df output, it is fine). You can add an entry to /etc/fstab file to mount the ramfs during the boot.
3 - tmpfs
The tmpfs is derivative of ramfs. It is easy and short to describe tmpfs after ramfs. The tmpfs is created to add size limit and ability to use the swap in case of virtual memory system needs memory.
Configuring tmpfs is similar to ramfs, we only need to create the mount point and mount it.
[root@localhost /]# mkdir /tmp/tmpfs [root@localhost /]# mount -t tmpfs -o size=64m tmpfs /tmp/tmpfs [root@localhost /]# mount | grep tmpfs tmpfs on /tmp/tmpfs type tmpfs (rw,size=64m) [root@localhost /]# df -h | grep tmpfs tmpfs 64M 0 64M 0% /tmp/tmpfs
Similar to ramfs, you can add an entry to /etc/fstab file to mount the tmpfs during the boot. In addition, tmpfs' size limit can be adjusted on run time (mount -o remount ...).
Summary
| ramdisk | ramfs | tmpfs | |
| Size Limit | Yes | No | Yes |
| Resizable | Yes (on boot) | Yes (no limit!) | Yes (on runtime) |
| Use swap | No | No | Yes |
Configuring Static Routes on Linux
How to configure static routes on linux ?
This question has been asked many times and I decided to keep the answer here. Actually there is no accurate answer because it depends on the distribution. Therefore this solution covers only RedHat and Fedora.
Static route configuration is stored in a /etc/sysconfig/network-scripts/route-interface file. For eth0, static routes would be stored in the /etc/sysconfig/network-scripts/route-eth0 file.
The route-interface file has two formats:
IP Command Arguments Format
default 192.168.0.1 dev eth0 10.0.0.0/24 via 192.168.0.1 dev eth0 192.168.1.0/24 via 192.168.0.1 dev eth0
Network/Netmask Directives Format
ADDRESS0=10.0.0.0 NETMASK0=255.255.255.0 GATEWAY0=192.168.0.1 ADDRESS1=192.168.1.0 NETMASK1=255.255.255.0 GATEWAY1=192.168.0.1