Users are not allowed to create hard links for directories. This might transform the directory tree into a graph with cycles, thus making it impossible to locate a file according to its name.
Links can be created only among files included in the same file system. This is a serious limitation since modern Unix systems may include several file systems located on different disks and/or partitions, and users may be unaware of the physical divisions between them.
In order to overcome these limitations, soft links (also called symbolic links) have been introduced. Symbolic links are short files that contain an arbitrary path name of another file. The path name may refer to any file located in any file system; it may even refer to a nonexistent file.
The Unix command:
Creates a new soft link with path name f2 that refers to path name f1.
Proftpd service may not start after fresh install from a Virtuozzo template
Resolution
Change the /etc/xinetd.d/xproftpd file and restart services
Log as root to your box
Open the /etc/xinetd.d/xproftpd file using a text editor
vi /etc/xinetd.d/xproftpd
Change value of “disable =” to “yes”.
Restart xinetd service
/etc/init.d/xinetd restart
Start proftpd service
/etc/init.d/proftpd start
Reference: http://parallels.com/
MySQL database does not work and returns “Can’t create/write to file” error
The problem is related to the mysql directory permission.
‘mysql’ user is not able to create a temporary file in /var/lib/mysql/ directory due to permissions lack
# ls -lda ~mysql/
drwxr-xr-x 5 root mysql 4096 Aug 31 09:56 /var/lib/mysql/
The solution is to go to /etc/init.d/mysqld_app_init file and change
chown root.mysql /var/lib/mysql
to
chown mysql.mysql /var/lib/mysql
Then restart mysqld service or just change owner of /var/lib/mysql directory to “mysql” instead of “root”
chown root /var/lib/mysql
Advanced tool to enable/disable recursive DNS lookups
DNS recursion support is defined under BIND 9, using the `recursion’ and the `allow-recursion’ directives, as part of the options grammar.
Download
http://download.swsoft.com/ensim/download/pro/linux/kb/2344/recursivedns
Installation Instructions
Download the script and copy in “/usr/lib/opcenter/bind/” directory.
recursivedns : ‘recursivedns’, allows you to modify the DNS recursion settings for your EPL server.
Invoking the script
To display the recursion settings, just run `recursivedns‘
To turn on recursion support, run `recursivedns on‘
To turn off recursion support, run `recursivedns off‘
To allow recursion to all hosts, run `recursivedns +all‘
To disallow recursion to all hosts, run `recursivedns -all‘
To allow recursion to a particular host, run `recursivedns +HOST‘
To disallow recursion to a particular host, run `recursivedns -HOST‘
To display the usage, run `recursivedns –help‘
Error message ‘Invalid cross-device link’ in site-admin web-interface
System has hard cross-device links. For example, /usr/tmp linked to /var/tmp and /var mounted to a separate partition.
Example:
/usr/tmp linked to /var/tmp and /var mounted to a separate partition.
To fix the problem:
1. Create /usr/.tmp directory
2. Add the following entry to the /etc/virtualhosting/tmpdirs:
3. Restart epld
or
Reference : http://parallels.com
