Lab46 Wiki

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=====unix Keywords=====
====PATH====
===Definition===
PATH is an environmental variable that specifies a set of directories where executable programs are located.

===Demonstration===


<cli>
lab46:~$export PATH=$PATH:/home/jdavis34/src/unix
</cli>
==== Daemons====
===Definition===
A daemon is a computer program that runs in the background as a process, instead of running in the foreground. Rather than being directly controlled by the user. Often these are used to start processes at a particular time, and or to maintain certain processes are always running.


====Wild Cards====
===Definition===
Various tools that are very powerful in the land of UNIX. These enable a user to control the output of commands without having to specify the exact context of the name of a file.

* zero or more of “any” character

? used to represent one of "any" character

\ will ignore such things as space if the variable name isn't one string.

” ” (or ' ') quote the enclosed characters

[ ] character class - match any of the enclosed characters.

[^ ] inverted character class - do not match any of the enclosed characters.

====who====
===Definition===
who - will print a list of all the current users logged in to a specific system.

===Demonstration===
<cli>
jdavis34@lab46:~/src/cprog$ who
NAME       LINE         TIME             IDLE          PID COMMENT
jjohns43 + pts/24       2012-01-23 12:18  old          701 (cpe-74-65-82-173:S.0)
skinney1 + pts/35       2012-03-16 10:15 20:26       27443 (65-124-85-125.dia.static.qwest.net)
mfaucet2 + pts/65       2012-03-09 17:09  old        28217 (55:S.0)
thakes3  + pts/68       2012-03-16 19:16 00:01       17986 (cpe-69-207-208-154:S.0)
jdavis34 + pts/22       2012-03-06 12:57 00:18        2741 (cpe-69-205-141-69:S.0)
thakes3  + pts/76       2012-03-16 15:41 00:02        6590 (cpe-69-207-208-154:S.2)
thakes3  + pts/101      2012-03-16 20:32 00:01       19641 (cpe-69-207-208-154:S.1)
jjohns43 + pts/82       2012-02-27 11:03  old        26118 (cpe-74-65-82-173:S.0)
</cli>

====cron/crontab====
===Definition===
This could be tied to daemon, but is the means of setting a daemon in the system. It is a time based job scheduler used to run periodically at certain times or dates. often used to automate system processes.

===Demonstration===
<cli>
lab46:~$ cd src
lab46:~/src$ gcc -o hello hello.c
lab46:~/src$ ./hello
Hello, World!
lab46:~/src$ 
</cli>
====at/atrm====
===Definition===
(at) is a powerful tool also used to schedule task, but for a single time occurrence. atrm is used to remove specific jobs, which can be done by following the command with the jobs PID number.

===Demonstration===
<cli>
lab46:~$ cd src
lab46:~/src$ gcc -o hello hello.c
lab46:~/src$ ./hello
Hello, World!
lab46:~/src$ 
</cli>
====ps====
===Definition===
ps gives a snapshot of the current processes.

===Demonstration===
<cli>
jdavis34@lab46:~/src/cprog$ ps
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
jdavis34  2741  0.0  0.1  13660  1916 pts/22   SNs  Mar06   0:00 /bin/bash
jdavis34  7001  0.0  0.1  13676  2028 pts/49   SNs  Mar16   0:00 /bin/bash
jdavis34  7004  0.0  0.1  13676  2032 pts/90   SNs  Mar16   0:00 /bin/bash
jdavis34 12154  0.0  0.3  42844  5376 pts/22   SN+  Mar10   1:04 irssi
jdavis34 20760  0.0  0.8  54232 13632 pts/49   SN+  Mar16   0:00 gdb bignum
jdavis34 29021  0.0  0.1  13636  1964 pts/8    SNs  08:48   0:00 -bash
jdavis34 29024  0.0  0.1  61848  2352 pts/8    SN+  08:48   0:00 screen -r
jdavis34 29203  0.0  0.0   8588   988 pts/90   RN+  09:46   0:00 ps u
</cli>
====kill====
===Definition===
kill is a very powerful command with a huge list of arguments that follow it, generally used to kill a process.

===Demonstration===
Refer to the previous word for seeing what process was killed. The argument -9 is OP...
<cli>
jdavis34@lab46:~/src/cprog$ kill -9 20760
jdavis34@lab46:~/src/cprog$
</cli>
=====unix Objective=====
====unix Objective====
State the course objective

===Definition===
In your own words, define what that objective entails.

===Method===
State the method you will use for measuring successful academic/intellectual achievement of this objective.

===Measurement===
Follow your method and obtain a measurement. Document the results here.

===Analysis===
Reflect upon your results of the measurement to ascertain your achievement of the particular course objective.

  * How did you do?
  * Is there room for improvement?
  * Could the measurement process be enhanced to be more effective?
  * Do you think this enhancement would be efficient to employ?
  * Could the course objective be altered to be more applicable? How would you alter it?
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