Updated: 2014-12-06 06:01 EST
____ _ ____ ____ | _ \| | ___ __ _ ___ ___ | _ \ ___ / ___|___ _ _ _ __ ___ ___ | |_) | |/ _ \/ _` / __|/ _ \ | | | |/ _ \ | | / _ \| | | | '__/ __|/ _ \ | __/| | __/ (_| \__ \ __/ | |_| | (_) | | |__| (_) | |_| | | \__ \ __/ |_| |_|\___|\__,_|___/\___| |____/ \___/ \____\___/ \__,_|_| |___/\___| _____ _ _ _ | ____|_ ____ _| |_ _ __ _| |_(_) ___ _ __ | _| \ \ / / _` | | | | |/ _` | __| |/ _ \| '_ \ | |___ \ V / (_| | | |_| | (_| | |_| | (_) | | | | |_____| \_/ \__,_|_|\__,_|\__,_|\__|_|\___/|_| |_|
Dogbert on satisfaction surveys
When you are done your evaluation do
touch .courseval_done in your
Assignments directory on the CLS and the nag messages will go away.
Reminder: There are now three quizzes that you need to complete on Blackboard as part of your term Quiz mark.
Check the due date for each assignment and put a reminder in your agenda, calendar, and digital assistant.
The worksheets are available in four formats: Open Office (ODT), PDF, HTML, and Text. Only the Open Office format allows you “fill in the blanks” in the worksheet. The PDF format looks good but doesn’t allow you to type into the blanks in the worksheet. The HTML format is crude but useful for quick for viewing online.
Do NOT open the ODT files using any Microsoft products; they will mangle the format and mis-number the questions. Use the free Libre Office or Open Office programs to open these ODT documents. On campus, you can download Libre Office here.
PS1, cd, find, less, ls, man, mkdir, passwd, pwd, rmdir
cat, clear, cp, find, grep, history, less, man, mv, rm, sleep, touch
date, head, nl, tail, tr, wc
chmod, ls -lid, umask
Take notes in class! Your in-class notes would go here.
last- last logins
md5sum - checksum (like
sum but better)
When you are asked to count arguments that are separated by spaces, the command lines are always printed using a monospace, fixed-width, Courier-style font where every character, including a space, has the same width. If you couldn’t fit a capital
M into the gap, there is no space there:
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM 'def' ' ghi ' it's 'mno ' ' pqr' 's' '' ' ' MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
On the afternoon of November 25 a Linux II student ran a
bash script that ran itself. This caused an “infinite loop” of processes to be created. At 15:43 the system ran out of memory and called the
oom-killer (out-of-memory killer) to terminate some tasks, but the script just created more to replace them. Students working in my lab alerted me to the CLS problem around 15:50. I wasn’t able to get any of my
root shells to respond, so I didn’t know what was wrong. I had to go back to my office and reboot the system around 16:15.
I ran a check of
lastcomm and discovered repeated executions of
bash by a student.
I went to the student’s home directory and looked for recent files:
# find . -mtime -1 . ./.viminfo ./.bash_history ./CST8177-14F/Assignments/practice ./CST8177-14F/Assignments/practice/myscript.sh ./CST8177-14F/Assignments/practice/foo ./CST8177-14F/Assignments/practice/test1 ./CST8177-14F/Assignments/practice/bar
I read each of the script files in the list and discovered that the file
bar contained this line that called itself:
./bar a "b c" 'a '
BINGO! I disabled that file and sent email to the student.
I turned on process limits in the system-wide
/etc/bash.bashrc so that no student can run more than 50 processes at the same time.
Student sends me email talking about using Linux skills in Ottawa:
Currently, I am doing part-time work (volunteering) at the National Capital FreeNet. They use Ubuntu Desktops and Linux servers. Skills you taught me are coming yet again, very useful. Especially, those you tested me on. Linux rules at the NCF. I think you were one of their first Sys Admins.
I was NCF employee #2. I worked there from 1993 to 1996, in the era of dial-up modems. The password file had over 50,000 accounts in it, with over 300 people connected to the system at the same time.
If only 1% of your users have problems, what does that mean when there are over 50,000 users?
A student in Linux I this term uses Linux to fix Windows:
Just thought you might find this interesting since it’s relevant to what we’re learning in CST8207. My aunt and uncle are hosting some friends from Cuba, and they have been (among other things) having fun using the internet on my uncle’s laptop. Naturally, since it’s a Windows laptop, the system has gotten bogged down in crap to the point that you can’t do much on it anymore.
My approach to this? Create a Ubuntu 14.04 live USB stick. I configured it to reserve 2GB on the stick to carry data between reboots, and installed ClamAV on the USB install. I then successfully mounted the Windows partition in Linux as /home/ubuntu/ntfs, and am watching ClamAV scan things on the Windows partition as I write this e-mail - in fact, it just detected a trojan in the Program Files directory somewhere (I’m sure it’s probably not the only thing wrong with the system, though). Additionally, I’ve been looking around the file system in a few of the “usual suspect” locations for adware, and then using the find command to locate all instances of anything that shouldn’t be there and delete them.
So, to conclude this tale, it turns out this approach worked - ClamAV found and deleted enough viruses that, combined with a bit of poking at the NTFS filesystem in Ubuntu (to delete any obvious malware), I was able to get the Windows OS at least to a point where it mostly worked again. From there, Windows-based anti-malware and anti-virus programs were enough to finish the job, and the laptop now boots up and runs cleanly.
Effectively, I rescued an inoperable Windows install using a Ubuntu live USB stick, with minimal risk of cross-contamination to another system. If I had plugged the laptop’s hard drive into another Windows machine (a potentially viable approach), it may have become infected with the viruses on the laptop.
As a side note, I also discovered in the process that the NTFS file system itself had some (mild) issues with corruption. GPartEd could read the FAT32 boot loader partition and the small NTFS recovery partition, but was not able to retrieve any information about the primary Windows partition. I was still able to mount the Windows partition and access it, so I scheduled a bootup checkdisk operation in Windows, which found and corrected a few problems in the file system.
Author: | Ian! D. Allen - email@example.com - Ottawa, Ontario, Canada | Home Page: http://idallen.com/ Contact Improv: http://contactimprov.ca/ | College professor (Free/Libre GNU+Linux) at: http://teaching.idallen.com/ | Defend digital freedom: http://eff.org/ and have fun: http://fools.ca/
Author Ian! D. Allen