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Technical information for web projects

Direct editing via SSH (Telnet replacement)

Direct editing through an SSH session (using the “dialog” server) requires fundamental knowledge about the Unix/Linux operating system, especially file management.

To work directly in the web directory, one has to establish a secure connection to the server (with a student or employee account). After login, your working directory will be your own Unix home directory. An AFS Token will be provided automatically. Use cd to change directories to the respective web project directory (for example /afs/ to be able to work there.

Transfer via SCP or SFTP (FTP replacement)

For transfering data from a local computer to the web directory or vice versa, make sure to establish an encrypted connection with SCP or SFTP (e.g. WinSCP or Filezilla) to the server (with your student or employee account). The server is only accessible within the university network UKLAN, for access from outside please establish a VPN connection previously.

More: Uploading websites

Available storage space

The storage requirements of a web project have been estimated when applying for it. The remaining storage space can be checked through an SSH session via the “dialog” server (see above).

How to access this information depends on the type of underlying storage filesystem (AFS or NFS). AFS projects were created up to 2018, NFS projects were created starting 2018. You can also determine the type of file system in use by looking at the first part of the project’s directory name. AFS project’s paths begin with or “/afs/” while NFS project’s paths begin with “/nfs/”.

Available storage space for AFS projects

After login through SSH, change into project directory and execute the fs lq command:

    cd /afs/

    fs lq

Example output:

    Volume Name                    Quota       Used %Used   Partition               750000     592974   79%         47%

In the column labelled “Quota”, the total provisioned disk space is displayed, while the column “Used” contains the amount of disk space already in use, both in measures of kilobytes.
So in the above example, 157026 kB are still available (approx. 150 MB).
If the available space is not sufficient, please send an e-mail to the Webmaster. (in time!)

Available storage space for NFS projects

Unfortunately, the remaining disk space cannot be determined as easily for NFS projects as can be for AFS projects. You will have to take a small detour.
After login, the command du -sh will display the amount of storage space used when called with the name of the appropriate project directory.


    jdoe2@dialog6:~$ du -sh /nfs/projekt/testblog
    6.3M    /nfs/projekt/testblog

In this example, there are currently 6.3 MB of storage space in use. Sadly, this does not show the amount of space still available. The default quota for NFS projects is 2 GB, so you can subtract the amount used from this value. Of course, you may have applied for a larger size when the web project was created. Please refer to your records or ask the person that originally requested the web project. If the original creator is no longer available, get in touch with the Webmaster team.

Conventions, especially for file names

File names should not contain any umlauts, no spaces, no ß or any other additional characters. Exceptions: full stop, minus and underscore.
Otherwise internet browsers won't be able to open the documents

More: Rules and Conventions concerning HTML documents of the Cologne webserver

Backup of the data

The data of web projects (i.e. HTML documents, pictures, PHP scripts, MySQL databases) are backed up by the RRZK on a regular basis. If you need to access a deleted or overwritten file of a web project folder, please get in touch with the Webmaster immediately.

Databases (MariaDB/MySQL) are being backed up in a way such that they can be restored to their previous state at any given time within the last 14 days (point-in-time recovery). Additionally, there is an archive copy available for 8 weeks. As restoring databases takes some time, it may be advisable to create a current database backup before carrying out larger maintenance tasks (e.g. version updates of a web application).

More: Data export with PHPMyAdmin

Paths of Directories

New projects are created within RRZK’s NFS filesystem. The paths of new web projects begin with


Projects created up to 2017 were set up to use the AFS filesystem. For these projects, the respective paths begin with


Below projektname, the following directories are available by default:

  • http/docs/ for “regular” HTML documents, PHP scripts, pictures, etc.
  • http/cgi/ for Perl or Python scripts
  • conf/ contains the server configuration and cannot be changed by users
  • logs/ contains the web server’s log files. For AFS projects: the error log only, for NFS projects: both access and error logfiles.

Please do not attempt to change this basic directory structure. Put your content into the appropriate directories (http/docs/ or http/cgi/) to make it available publicly. For files that belong to the project but should not be accessible through the web server, you can create subdirectorys on the “projektname” level (e.g. for internal notes and documentation).

More : AFS-Andrew File System

Write permissions for web server in projects

As the administrator of a project, you may give write permissions to the internal web server user for certain directories. Typically, doing so is required when using content management systems or similar software that accepts user uploads.

More: Write permissions for web server in projects

Composer-managed software

Composer-managed software installations are not expedient in the environment of web projects. Neither users nor Composer have direct access to the delivering web servers. The only access is to a mediating "dialog server". Due to this circumstance, Composer functions, especially the resolution of software dependencies, can lead to misleading results because they are executed on the wrong systems.



If you have any questions or problems, please contact the RRZK-Helpdesk