General Use
How do I reboot the computers when they are acting strange?
Currently, it is not possible to reboot the computer. Sometimes pressing Control + Sleep/Suspend (located at the top right of the keyboard; looks like a half moon) makes a locked computer respond (it also makes the sound work again if it has stopped functioning).
How do I logout a crashed terminal?
Logon to another terminal. Press the right mouse button and select Emergency Log-out. The crashed terminal and the terminal you just logged on to should now logout and then show a logon screen. The Emergency Log-out is actually just a kill command:
kill -9 -1
The command above kills all your processes, including any background jobs! When running Emergency Log-out, this command is run on all terminals.
I forgot to logout; how do I do that from home?
You can use SSH to login.gbar.dtu.dk, and kill your processes (essentially the same as your session). The following steps should do it:
- ssh USERNAME@login.gbar.dtu.dk
- run
pkill -9 -u $USER
in the terminal, and you should be successfully logged off.
And that should fix it. Notice that this is required to logout, unlike the Windows databars where you're automatically logged out after some idle time.
How do I logout if the Window Manager halts?
Occasionally, it's impossible to logout of the window manager (e.g., IceWM). You can use Ctrl-Alt-backspace twice to logout. This will crash your instance of the X server and causes you to logout.
I cannot create files on the G-Bar
You are most likely violating your quota by a considerable factor (please read below how to check this). Please [Contact|contact us], and request a higher quota.
How can I check how much space I'm using?
You may have gotten an email informing you that you violated your quota. You can use:
du -sh ~
in a terminal which outputs the total space consumption of your home directory (the options stand for human-readable, and summary). To only check for files with sizes in megabytes (or gigabytes), use the following command:
du -h ~ | grep -E "^ *[0-9]+[MG]"
Please note that you cannot see how much space you are using on the G-Bar system on CampusNet.
Can I lock my session ?
Yes, it's possible to lock your session at a terminal by running
xlock &
However, if you plan to leave for more than a few moments, we encourage you to get a Smartcard as you will be occupying a terminal when locking it, and may risk that your session (and programs) will be crashed. By using a smart-card, you will also be able to continue your session at a different terminal.
How can I split large files to fit on floppy disks?
You should use the command split. For example, to split a file into pieces of size 1440 kB, use the command
split -b 1440k filename
For more information, consult the man page for the split command.
Why are the UNIX files I took home looking strange?
This is because Windows and UNIX use different file formats for text files.To solve the problem, you must use the two utilities dos2ux and ux2dos. For example, to convert DOSFILE.TXT to unixfile, use the following command:
dos2ux DOSFILE.TXT > unixfile
Conversely, to convert unixfile to DOSFILE.TXT, use:
ux2dos unixfile > DOSFILE.TXT
I'm running a large simulation, but the server I'm using is 60% idle
First of all, you shouldn't run large simulations on the normal G-Bar machines, but rather use the HPC machines.
The G-Bar servers usually consists of about 48 CPUs. Some more, some less. This means that if you are running a single-threaded program, one CPU will be dedicated to your program, while the other CPUs will be idle, waiting to service other programs. Even if your program is multi-threaded, there is an upper limit of four CPUs per user, so your program will never be able to use all the available recourses.
How do I connect to DTU's wireless network?
We have a dedicated page for this. Check out DTU Wireless.
Printing
Can I print several pages on a single page?
Yes. You can use the mpage command with the following options:
- -2 Gives you two pages on one.
- -4 Gives you four pages on one.
- -8 Gives you eight pages on one.
Remember to set the papersize to a4 with the option -b a4.To use these options you should use the following syntax:
mpage -4 -b a4 filename.ps > newfile.ps
Where filename.ps is the file you want to print and newfile.ps is the new file with the number of pages on one sheet. To use this command, the input must be a PostScript file.
For text files, also check out the command a2ps (available as /usr/unic/bin/a2ps), which is a utility to convert text files to Postscript files, with lots of options. Use man a2ps to read more about it.
How do I collate?
The printer does not collate by default when printing several copies of a document. This behavior may be changed by using:
lpr -o Collate=True
How do I print from the G-Bar ?
Choose "Print" from the program you are using. In the "Print Command" box type:
lp -d [printername]
The printernames can be found here.
For more info about printing see Printing from the G-Bar.
How do I open and print PDF documents ?
To open the PDF document, open XFE (found in the menu under Desktop Environment->XFE) double click the pdf file and Adobe Acrobat should start. Alternatively, you can use the terminal by typing
acroread file.pdf &
To print your file, choose print in the File menu of Acrobat Reader.