Splitting FLAC files based on CUE

Install the following packages

• cuetools
• shntool
• flac

sudo apt-get install cuetools shntool flac

Now the FLAC file can be split as follows:

cuebreakpoints inputfile.cue | shnsplit -o flac inputfile.flac

The result will be as follows: 

split-track01.flac
split-track02.flac
....

Kubuntu DNS settings

Seem like DNS settings are no longer stored in resolv.conf but this can still be extracted from the netwok Manager CLI.

nmcli dev show [device] e.g. nmcli dev show wlan0

This will return information including:

IP4.DNS[1]:
IP4.DOMAIN[1]:

Therefore a quick awk can return the value needed:

nmcli dev show wlan0 | grep IP4.DNS | awk -F: '{ print $2 }' | awk '{ print $1 }'

To test if a port is open on linux

Well I wanted to test if a linux box is ready to receive syslog log files remotely and used netcat / ccat / nc for the purpose.

It is a server/client application whereby you run the server in listen mode and then start the client on a different host and connect to the server, it can create both tcp and udp connections.

I had some trouble with the syntax on Ubuntu 10.04 Lucid Lynx and hence will post the commands that worked for me:

Server:

user@server:~$ sudo nc -l -u 514

-l : is for listen
-u : is for udp

Client:

user@client:~$ nc 192.168.0.1 -u 514

where 192.168.0.1 is the ip of the server
If it connects you can then type anything in the client and it will display in the server window confirming the port is available and no firewall is blocking teh traffic, hence you can move to the application layer.

Can't ping FQDN in Ubuntu

I created a local DNS zone ending in .local and experienced weird DNS behaviour; dig worked 100%

It seems the avahi-daemon interferes with the normal resolving process. It’s DNS caching borks the normal functionality

The fix:

# shut it down
sudo /etc/init.d/avahi-daemon stop
# stop it starting at the next reboot by removing the startup links
sudo update-rc.d -f avahi-daemon remove
 Removing any system startup links for /etc/init.d/avahi-daemon ...
   /etc/rc1.d/K86avahi-daemon
   /etc/rc2.d/S50avahi-daemon
   /etc/rc3.d/S50avahi-daemon
   /etc/rc4.d/S50avahi-daemon
   /etc/rc5.d/S50avahi-daemon

Symbolic Links in ProFTPd

A symbolic link (also referred to as a "symlink") is a file whose contents contain the name of the file to which the symbolic link points. For example:

  lrwxrwxrwx   1 root     root           11 Mar  2  2000 rmt -> /sbin/rmt

The file rmt contains the nine characters /sbin/rmt. The reason symbolic links fail when chroot(2) is used to change the position of the root (/)of the filesystem is that, once / is moved, the pointed-to file path changes. If, for example, if chroot(2) is used to change the filesystem root to /ftp, then the symlink above would be actually be pointing to /ftp/sbin/rmt. Chances that that link, if chroot(2) is used, now points to a path that does not exist. Symbolic links that point to nonexistent files are known as dangling symbolic links. Note that symbolic links to files underneath the new root, such as symlinks to a file in the same directory:

  > pwd
  /var/ftp
  > ls -l
  -rw-r--r--   1 root     root            0 Jan 16 11:50 tmpfile
  lrwxrwxrwx   1 root     root            7 Jan 16 11:50 tmplink -> tmpfile

will be unaffected; only paths that point outside/above the new root will be affected.

so clearly this will not work in a ProFTPd default directory

The trick is to use re-mount the directory you want listed again

To have an exact duplicate of the /var/ftp/incoming directory available in /home/bob/incoming and /home/dave/incoming, use one of these commands:

• Linux (as of the 2.4.0 kernel):
  

    mount --bind /var/ftp/incoming /home/bob/incoming
    mount --bind /var/ftp/incoming /home/dave/incoming

  
  or, alternatively:
  

    mount -o bind /var/ftp/incoming /home/bob/incoming
    mount -o bind /var/ftp/incoming /home/dave/incoming

  
  

On Kubuntu 9.x with kernel 2.6.28-11-generic the command was:

sudo mount --bind /media/disk/Sorted\ MP3/ /home/sharedftp/download/Music/

This mounted the Sorted MP3 directory under the FTPServer DefaultRoot directory.

In order to have these tricks persist, to survive a system reboot, the /etc/fstab file may need to have these mounts added

fstab

to mount a folder locally to another folder using --bind, ie. mount --bind /path1/ /path2/

/path1 /path2 bind defaults,bind 0 0

To mount a folder with spaces in fstab use "\040"

/media/disk/Sorted\040MP3/ /home/sharedftp/download/Music/ bind defaults,bind 0 0