Htam::CS.FAQ

1. What OS do you use?
2. What common applications do you use?
3. How many virtual desktops do you use?
4. How many computers do you have?
5. Why does free indicate that memory is used up only after a few hours of uptime?
6. How to auto-start applications and/or set environmental variables when starting KDE?
7. How to mount a CD image file?
8. I have a class graded on geometric mean; how do I take the cube root in bc?

1. What OS do you use?
   I use GNU/Linux. The distribution I most commonly use is Fedora Core.

2. What common applications do you use?
   

   desktop environment	KDE
   X Window System	X.org
   shell	bash
   secure shell, copy	ssh, scp
   terminal emulator	rxvt, screen, mrxvt
   text editor	vim
   web browser	Mozilla Firefox, lynx, wget
   email reader	Mozilla Tunderbird
   authoring	latex, dvips, dvipdf, ooffice
   IM, telephony	pork, skype
   mathematics	bc, Mathematica, jmath
   media	mplayer, audacity, play
   utilities	ls, cat, more, tail, grep, crontab, rsnapshot
   programming	perl, php, gcc

3. How many virtual desktops do you use?
   Twelve: keyed to Ctrl-F1 through Ctrl-F12.

4. How many computers do you have?
   Around four.

5. Why does free indicate that memory is used up only after a few hours of uptime?
   Read man free and try to understand the "buffer adjusted" line.
   In particular, memory is wasted if not used, so much of the unused portion is used for caching data recently read from the hard disk drive.
   This does not impact performance because these can be rapidly released; hence for processes, the effective memory usage is as what the "buffer adjusted" line indicates.

6. How to auto-start applications and/or set environmental variables when starting KDE?
   Try putting shell scripts in ~/.kde/env/.

7. How to mount a CD image file?
   Use the loop device to mount an ISO 9660 CD filesystem data file like this: mount -o loop /path/to/image.iso /mnt/dir/.

8. I have a class graded on geometric mean; how do I take the cube root in bc?
   bc is an arbitrary precision calculator language.
   We can load the math library by invoking bc -l
e(x) is e^x and l(x) is the natural logarithm of x.
   Therefore we can do e(l(27)/3) to take the cube root of 27, or raise numbers to arbitrary real powers via this mechanism.
   P.S., Ec121a was grade on an unweighted geometric mean of three things: homework, midterm, and final.