If you want unmount a partition and get a message ” device is busy ” type:
#~ fuser -vu mountpoint
( replace mountpoint with your real mountpoint )
The system will respond with one or more process pid(s)
You can send then a kill or a kill -9 if needed to stop
the process and unmount your partition.

If you .want your Linux system starting with numlock enabled at startup,
you need only install the package numlockx from your package manager

Mit dem Befehl “du” lassen sich auf der Shell bequem Ordnergrössen anzeigen.
Als Beispiel:
~$ du -sh /home
zeigt die Gesamtgrösse von /home an.
Dabei steht Parameter s für summarize und h für human readable,
die Grösse des Ordners wird daher in GB oder MB angezeit und nicht in Blöcken.
Für mehr Infos und Optionen:
~$ du –help

To display the mailqueue type:
postqueue -p

To deliver messages in the queue type:
postqueue -f

Das Programm mirrordir ermöglicht ganz einfachen Datenabgleich, wobei im Zielordner nicht nur Daten hinzugefügt oder erneuert werden sondern auch gelöscht werden falls sie im Quellordner nicht mehr existieren.
Syntax: ~$ mirrordir -v /home/myaccount/datei1 /home/myaccount/datei2
Download des Programms unter http://www.sfr-fresh.com/unix/misc
Debian Anwender können das Programm über Apt installieren.

To test the connection between 2 internet location / machines type:
~$ traceroute rootserver.lu
( Replace with your domain name, host name or IP Address )
traceroute to rootserver.lu (78.47.146.25), 30 hops max, 40 byte packets
1 speedport.ip (192.168.2.1) 0.302 ms 0.297 ms 0.319 ms
2 * * *
3 217.0.67.154 (217.0.67.154) 51.127 ms 50.901 ms 50.529 ms
4 217.239.40.222 (217.239.40.222) 53.617 ms 55.222 ms 52.688 ms
5 dtag-gw.hetzner.de (193.159.226.2) 53.424 ms 55.301 ms 55.647 ms
6 hos-bb1.juniper1.rz4.hetzner.de (213.239.240.200) 56.871 ms 57.604 ms 71.951 ms
7 gi.4.1.rs3k16.rz9.hetzner.de (213.239.244.61) 59.760 ms 58.135 ms 56.870 ms
8 gate.my-web-host.org (78.46.99.143) 58.378 ms 115.404 ms 58.352 ms
9 rootserver.lu (78.47.146.25) 57.858 ms 56.213 ms 57.863 ms

In some php 5 versions the flle upload is bugging by default.
Open php.ini and add the following line ( or uncomment if present but not enabled )
upload_tmp_dir = /tmp

Monitoring your system basics
 
To check the disk usage on your system
~# df -h

To check the memory allocation and usage
~# free -m

To visualize your CPU information
~# cat /proc/cpuinfo

To check your network configuration
~# ifconfig

To visualize the running processes, CPU Load and Memory
~# ps aux

To see lifetime running processes
~# top
( type q to leave the program )

Setting File and Folder Ownership
 
Every file or folder belongs to an owner and a group
To change ownership use the syntax:
~# chown username:usergroup filename
~# chown username:usergroup foldername
To change ownership recursively, meanwhile all files inside a folder:
~# chown -R username:usergroup foldername
To check and visualize your changes type:
~# ls -hal

Setting File and Folder Permissions
 
Permission are represented by a 3 digit numerical code
First Digit: Owner
Second Digit: Group
Third Digit: Everybody

Permission 0 = no access
Permission 4 = read
Permission 6 = read / write
Permission 5 = read / execute
Permission 7 = read / write / execute
To set permissions use syntax
~# chmod 644 filename
Setting filename to read/write (owner) and read (group and world)
To set permissions recursively for all files inside a folder use
~# chmod -r 755 foldername
Setting foldername and all files inside to raed/write/execute (owner) and read/execute ( group and world )

You can restrict your settings and give permissions only for specified files
~# chmod 644 *.php
Setting all php files inside this folder to read/write – read – read