Today we learned some basic commands in Unix and were given some time to “play” by using the commands to explore the system.
Today we learned about extended command mode for VI and the control key combinations that allow you to do shortcuts for things like cut and paste.These should be useful tools in speeding up things like Shell Scripting assuming i can remember them.
Today we wrote a shell script that converts numbers from base 10 (normal numbers) to base 2 (binary). This was useful because it helped understand the thinking process to develop the psuedocode for an assignment in another class where we were to make psuedocode for a binary converter. This was also useful in understand relations between commands for other Shell Scripts.
Today we learned how to write the shell script for a basic bot using II or IRC Improved. This was a useful demonstration of how multiple commands work together to form a script and how to look at coding and break it down in a manner that allows you to see what part of the script does what.
Listing used by typing the command ls. Listing does a variety of things. ls lists current files and directories in whatever directory you may be in while ls -l lists files running on the system, who ran them and the permissions for the files. ls -a is used to find hidden files or directories that are excluded from the standard ls command through use of a . before the name.
lab46:~$ ls Downloads Maildir bin closet in irc link longcat motd public_html src tmp
lab46:~$ ls -a . .config .irssi .ssh closet src .. .dbus .local .viminfo in tmp .117.swp .fluxbox .mozilla .xinitrc irc .Xauthority .gconf .openoffice.org .xsession-errors link .bash_history .gconfd .pine-passfile Downloads longcat .bash_logout .gvfs .pinerc Maildir motd .bashrc .indent.pro .profile bin public_html
lab46:~$ ls -l total 16 drwxr-xr-x 2 lgottsha lab46 6 Sep 20 15:14 Downloads lrwxrwxrwx 1 lgottsha lab46 18 Aug 28 10:37 Maildir -> /var/mail/lgottsha drwxr-xr-x 2 lgottsha lab46 4096 Sep 29 16:46 bin drwxr-xr-x 2 lgottsha lab46 32 Sep 15 16:17 closet -rw-r--r-- 1 lgottsha lab46 15 Sep 29 14:59 in drwx------ 4 lgottsha lab46 39 Sep 29 14:55 irc lrwxrwxrwx 1 lgottsha lab46 4 Sep 1 14:45 link -> file -rw-r--r-- 1 lgottsha lab46 58 Sep 13 15:57 longcat -rw-r--r-- 1 lgottsha lab46 1310 Sep 15 15:15 motd drwx-----x 2 lgottsha lab46 6 Aug 26 2009 public_html drwx------ 3 lgottsha lab46 34 Jan 20 2011 src drwxr-xr-x 2 lgottsha lab46 84 Sep 22 16:46 tmp
Ownership is the display of the user who owns a file, owndership can be seen with the ls -l command which displays it in the third column of the results
lab46:~$ ls -l total 16 drwxr-xr-x 2 //**lgottsha*//* lab46 6 Sep 20 15:14 Downloads lrwxrwxrwx 1 lgottsha lab46 18 Aug 28 10:37 Maildir -> /var/mail/lgottsha drwxr-xr-x 2 lgottsha lab46 4096 Sep 29 16:46 bin
Permissions are a users consent to access a file, Viewed with the ls -l command there are permissions for editing, opening/ viewing and executable and are displayed as a W, R or X under the ls -l command. Where these are located determines who has which permissions be it the owner, another group or something else.
lrwxrwxrwx* 1 lgottsha lab46 18 Aug 28 10:37 Maildir -> /var/mail/lgottsha drwxr-xr-x*2 lgottsha lab46 4096 Sep 29 16:46 bin drwxr-xr-x* 2 lgottsha lab46 32 Sep 15 16:17 closet -rw-r--r--* 1 lgottsha lab46 15 Sep 29 14:59 in
* indicates the permissions line
VI text editors insert mode. The mode that allows VI to actually edit text with in a file. Initially entered through the use of lower case “i” after initializing VI there are multiple other commands to enter insert mode.
#!/bin/bash a=0 echo -n "Please enter a Number: " read number until [ $number -eq 0 ]; do n=0 until [ `echo "$number-2^$n"|bc` -lt 0 ];do let n=$n+1 done let n=$n-1 let number=$number-`echo "2^$n"|bc` places="" for((i=0;i<$n;i++)); do places="${places}0" done places="1${places}" let a=$a+$places done echo "the binary value is $a" exit 0 ~ ~ ~ -- INSERT -- 1,1 All
A file in VI's insert mode.
VI's command mode is the environment you are in when initially opening VI. In command mode you cannot edit text by typing but can use a variety of commands to perform different functions on the file instead. The simplest commands are :q to quit :w to save your file :wq to save then quit and :q! to quit without saving
#!/bin/bash a=0 echo -n "Please enter a Number: " read number until [ $number -eq 0 ]; do n=0 until [ `echo "$number-2^$n"|bc` -lt 0 ];do let n=$n+1 done let n=$n-1 let number=$number-`echo "2^$n"|bc` places="" for((i=0;i<$n;i++)); do places="${places}0" done places="1${places}" let a=$a+$places done echo "the binary value is $a" exit 0 ~ ~ ~ :q
A file in VI's Command Mode being given the command to quit.
regular files are files that are not links or directories most regular files appears gray in color and can be read via the cat command.
lab46:~$ ls Downloads Maildir bin closet in* irc link longcat* motd* public_html src tmp
*indicates the regular files in my directory
Directories are places where files are stored. Much like folders for GUI users of operating systems like Windows. when shown via the ls command directories are blue and if you have permissions you may enter them via the cd command. The command for a knew directory is mkdir “Directory name”
lab46:~$ ls Downloads* Maildir bin* closet* in irc* link longcat motd public_html* src* tmp*
* Indicates the directories within my home directory
Files that are neither directories nor regular files. special files are yellow by default and usually device files thatrepresent the hardware components of the machin
lab46:/dev/input$ ls by-path event0 event1 mice* mouse0*
*special files representing the Mouse
killing a process sends a signal to it telling it to terminate. While there are a variety of kill commands for various situations Kill -9 will kill any process that you can kill. to kil something find the process you want via the ps command and type the kill command followed by the processes PID number.
lab46:~$ ps USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND lgottsha 2449 0.0 0.0 8580 896 pts/38 RN+ 12:07 0:00 ps u lgottsha 7752 0.0 0.1 13640 2008 pts/38 SNs 09:42 0:00 -bash lgottsha 23924 0.0 0.1 13660 2004 pts/29 SNs Sep20 0:00 /bin/bash lgottsha 31149 0.0 0.6 157312 7272 pts/29 SNl+ Sep29 0:00 vi
The kill command for vi in this situation would be kill -9 31146
Shell scripting is where a script is written for the shell or command line that causes something to happen. Shell scripts for unix start with the #!/bin/bash line,the initial characters known as sh and bang and the rest of the line specifying that the script is intended to run on the bash shell. Scripts can be used for a variety of things and are considered one of the most basic programming languages.
#!/bin/bash #B35T 5R1PT 3V4R echo -n "please enter your name: " read name #put user input into name echo "Hi, $name, We've had a slight weapons malfunction here,but we're fine here now, everything fine. How're you?" exit 0 ~
The code of a simple script
Viewing files is done via the cat command. When viewed the files text will be displayed on screen, however not all files are viewable. When nonviewable files are ran through car they will cause random code to appear on the screen and the user will need to crtl C to unlock their terminal. Only regular files will always be viewable.
lab46:/usr/games$ cat monop ELF>@@@h@@@@@@À@@@@dqdq hqhq`hq`p qq`q` @@DDPåtdgg@g@Qåt/lib64/ld-linux-x86-64.so.2GNUGNU¬Pßù*Uê6Å u½«[%+#"$&%' !)*( 3ªÏ ]-bÊ@÷qFjÃî}±2¿V É(!:ÕvérO; __gmon_start__libc.so.6fflushstrcpygetwexitsprintfsrandfopensetregidperrorsignalputsputchargetpidsbrkcallocstrlengetcharfseekctimestdoutstrcasecmpgetgid__ctype_b_locerrcreatfreadclose__ctype_tolower_locerrx_IO_getc__libc_start_mainwrit%uiee__x/0s`*Ps`Xs``s`hs`ps`xs`ss`_2.2.5s` s`
The result of using car on a nonviewable file
lab46:~/bin$ cat Password Ah-ah-ah. You didn't say the magic word.
The result of using cat on the file Password.
The windows equivalent of deletion. to remove a file you'd use the rm command followed by the name of the file you want to remove and responding yes to the prompt “remove regular file 'filename'?” with yes. You can only remove files that you have permissions to.
lab46:~$ ls Downloads bin in link motd src trashfile Maildir closet irc longcat public_html tmp lab46:~$ rm trashfile rm: remove regular empty file `trashfile'? yes lab46:~$ ls Downloads Maildir bin closet in irc link longcat motd public_html src tmp
State the course objective; define what that objective entails.
State the method you will use for measuring successful academic/intellectual achievement of this objective.
Follow your method and obtain a measurement. Document the results here.
Reflect upon your results of the measurement to ascertain your achievement of the particular course objective.
is it possible to create a “menu” to the games directory using shell scripts?
www.unix.com google
That it will be possible to make a link to the games directory and show games available using the cd,echo and ls commands using the echo and cd commands will put the user in the directory and ls will display the avalible games while echo will ask the user to pick a game.
With shell script
#!/usr/games echo -n "would you like to play a game?:" read word if [ "$word" = "yes" ] then echo "`cd /usr/games`" echo "`ls`" echo "Pick a game, any game..." else echo"THEN, YOU SHALL NOT PASS" exit 1 fi exit 0
Was unable to get directory to change to the games directory. The rest of the script worked well but was useless without the cd.
Based on the data collected:
My hypothesis was incorrect, the script failed to execute as expected. Some variable must not be being taken into account.
Concept may be doable but needs something additional to support the CD command. CD will not execute because the script is taking place in a subshell.
What is the question you'd like to pose for experimentation? State it here.
Collect information and resources (such as URLs of web resources), and comment on knowledge obtained that you think will provide useful background information to aid in performing the experiment.
Based on what you've read with respect to your original posed question, what do you think will be the result of your experiment (ie an educated guess based on the facts known). This is done before actually performing the experiment.
State your rationale.
How are you going to test your hypothesis? What is the structure of your experiment?
Perform your experiment, and collect/document the results here.
Based on the data collected:
What can you ascertain based on the experiment performed and data collected? Document your findings here; make a statement as to any discoveries you've made.
What is the question you'd like to pose for experimentation? State it here.
Collect information and resources (such as URLs of web resources), and comment on knowledge obtained that you think will provide useful background information to aid in performing the experiment.
Based on what you've read with respect to your original posed question, what do you think will be the result of your experiment (ie an educated guess based on the facts known). This is done before actually performing the experiment.
State your rationale.
How are you going to test your hypothesis? What is the structure of your experiment?
Perform your experiment, and collect/document the results here.
Based on the data collected:
What can you ascertain based on the experiment performed and data collected? Document your findings here; make a statement as to any discoveries you've made.