Linux Network Administration tools Graphics-related commands and Music-related commands

Network administration tools

netconf
(as root) A very good menu-driven setup of your network. pingmachine_name
Check if you can contact another machine (give the machine's name or IP), press <Ctrl>C when done (it keeps going).
route -n
Show the kernel routing table.
nslookup host_to_find
Query your default domain name server (DNS) for an Internet name (or IP number) host_to_find. This way you can check if your DNS works. You can also find out the name of the host of which you only know the IP number.
traceroute host_to_trace
Have a look how you messages trave to host_to_trace (which is either a host name or IP number).
ipfwadm -F -p m

(for RH5.2, seen next command for RH6.0) Set up the firewall IP forwarding policy to masquerading. (Not very secure but simple.) Purpose: all computers from your home network will appear to the outside world as one very busy machine and, for example, you will be allowed to browse the Internet from all computers at once.
echo 1 > /proc/sys/net/ipv4/ip_forward
ipfwadm-wrapper -F -p deny
ipfwadm-wrapper -F -a m -S xxx.xxx.xxx.0/24 -D 0.0.0.0/0
(three commands, RH6.0). Does the same as the previous command. Substitute  the "x"s  with digits of your class "C" IP address that you assigned to your home network. See here for more details. In RH6.1, masquarading seems broken to me--I think I will install Mandrake Linux:).
ifconfig
(as root) Display info on the network interfaces currently active (ethernet, ppp, etc). Your first ethernet should show up as eth0, second as eth1, etc, first ppp over modem as ppp0, second as ppp1, etc. The "lo" is the "loopback only" interface which should be always active. Use the options (see ifconfig --help) to configure the interfaces.
ifup interface_name
(/sbin/ifup to it run as a user) Startup a network interface. E.g.:
ifup eth0
ifup ppp0
Users can start up or shutdown the ppp interface only when the right permission was checked during the ppp setup (using netconf ). To start a ppp interface (dial-up connection), I normally use kppp available under kde menu "internet".
ifdown interface_name
(/sbin/ifdown to run it as a user). Shut down the network interface. E.g.: ifdown ppp0 Also, see the previous command.
netstat | more
Displays a lot (too much?) information on the status of your network.
 

Music-related commands

cdplay play 1
Play the first track from a audio CD. eject
Get a free coffee  cup holder :))).   (Eject the CD ROM tray).
play my_file.wav
Play a wave file.
mpg123 my_file.mp3
Play an mp3 file.
mpg123 -w my_file.wav my_file.mp3
Create a wave audio file from an mp3 audio file.
knapster
(in X terminal) Start the program to downolad mp3 files that other users of napster have displayed for downloading. Really cool!
cdparanoia -B  "1-"
(CD ripper)  Read the contents of an audio CD and save it into wavefiles in the current directories, one track per wavefile.  The "1-"
means "from track 1 to the last". -B forces putting each track into a separate file.
playmidi my_file.mid
Play a midi file.  playmidi -r my_file.mid  will display text mode effects on the screen.
sox
(argument not given here) Convert from almost any audio file format to another (but not mp3s).  See man sox.
 

Graphics-related commands

kghostview my_file.ps
Display a postscript file on screen.  I can also use the older-looking ghostview or gv for the same end effect. ps2pdf my_file.ps my_file.pdf
Make a pdf (Adobe portable document format) file from a postscript file.
gimp
(in X terminal) A humble looking but very powerful image processor. Takes some learning to use, but it is great for artists, there is almost nothing you can't do with gimp. Use your mouse right button to get local menus, and learn how to use layers. Save your file in the native gimp file format *.xcf (to preserve layers) and only then flatten it and save as png (or whatever).  There is a large user manual /usr/
gphoto
(in X terminal) Powerful photo editor.
giftopnm my_file.giff > my_file.pnm
pnmtopng my_file.pnm > my_file.png
Convert the propriatory giff graphics into a raw, portable pnm file. Then convert the pnm into a png file, which is a newer and better standard for Internet pictures  (better technically plus there is no danger of being sued by the owner of giff patents).