One Laptop Per Child is a brilliant idea that has the goal of bringing laptops to the underprivelaged children of the world. Announced to the public in January 2005 OLPC rolled out 1,000,000 laptops to several different countries during their initial release. While there were a number of different concepts preceding OLPC, it is the main program that has survived the startup period.
A major contributor to the success of OLPC is that companies such as Red Hat, and Microsoft are both contributing operating systems for the laptops. To me this is a step in the right direction for major companies. There are also companies that are working on making cheap but functional laptops such as the XO-2, and the CM1. If more companies followed these examples I have no doubt that every child in the world could have a working laptop and be able to get access to the educational material that is now available on the World Wide Web.
OLPC is by far not the only program of this nature that is out in the world today. Another major program is called Give 1 Get 1. This program allows you either buy a single unit for $199 and have it sent to a underprivelaged child somewhere in the world, or you can buy two units for $399 and keep the second unit for yourself. OLPC and Give 1 Get 1 while not 100% successful yet are both heading in the right direction.
OLPC is designed to help underprivelaged children across the globe get their own laptops. There are countires on every inhabited continent that participate in the program. As this program grows more and more children are able to get the education they have otherwise been denied. This is a very good thing in my book. With the way the world is changing getting an education is more and more important.
Unfortunately there is also a negative with the program. The "cheap" laptops are not widely available, and you can not go out to the store and just buy one. This can cause major problems with children being at risk for theft, as well as people taking advantage of the lack of availability by auctioning off the laptops on places like e-bay.
Sunday, March 29, 2009
Monday, March 9, 2009
Chapter 7 Review Questions
1.) Name three types of remote connectivity supported by Linux and explain why one is better than the other two.
SSH, the r-utilities, and Telnet. SSH is a more secure protocol.
2.) One advantage of Telnet is that:
It can be used on many different platforms, including Linux and Windows.
3.) Name three utilities that are part of the r-utilities and explain what each does.
There is rsh for executing a command on a remote host without actually logging on to the system, rcp which allows you to copy files between two hosts, and rlogin which lets you login to a remote system in a similar way to Telnet.
4.) The rcp program is able to copy files between:
Any two computers that are configure to use the r-utilities programs.
5.) Name the three types of authentication that SSH can use to connect to a remote system. Which is preferred as the most secure?
You can use the r-utilities, using passwords, or public key encryption. The public key encryption is the most secure.
6.) Which utility is used to prepare a set of keys needed to use public key encryption within SSH?
ssh-keygen
7.) Why might you need to use the -l option with the ssh command?
It tells you that you are wanting to access the user account that immediately follows the option.
8.) If you use the ssh command without first creating and storing a key pair on the remote host:
You are prompted for a password to aid authentication.
9.) If you have installed and configured r-utilities, then including a host and user name in your .rhosts file allows a person using the rcp command on another host to:
Copy files to or from your home directory without entering a password.
10.) SSH is commonly used in place of Telnet because:
SSH protocols use a more robust encryption algorithm than that used by Telnet.
11.) When using Telnet you might refer to VT100 because it is:
The most commonly used terminal emulation standard.
12.) Telnet is considered dangerous because:
It transmits data--including passwords--without encrypting them, so anyone on the network can see them by using special software.
13.) When using the wget command, you should include the http:// designation to download a Web page so that:
The program knows which protocol to use when accessing the server.
14.) Suppose you want to mirror a Web site to your local computer in order to study the information it contains. You intend to update the mirror once each month to view changes in the Web pages on the site. You are concerned that the Web site administrator will block access if he realizes you are mirroring the entire site instead of using a regular browser to access it. In order to reduce the chance that the wget program creates suspicion, you can:
Use the --random-wait option with wget.
15.) The rsync program is best suited for:
Synchronizing collections of files such as software development files.
16.) On a publicly available anonymous FTP server, the first level subdirectory that you should to to when locating files to download is virtually always:
/pub
17.) A graphical FTP client can be more convenient than a text-mode FTP client such as ncftp because:
The graphical program lets you see lists of files locally and remotely and drag and drop multiple files between systems.
18.) The ncftp package includes a utility that is similar in functionality to wget. This utility is called:
ncftpget
19.) If an IP address is not assigned explicitly when networking is configured, one must be obtained automatically from a server on the network using ________.
DHCP
20.) The process of resolving a domain name:
Determines the IP address associated with that domain name by contacting a DNS server.
21.) ping is used to test networking connections by:
Trying to contact systems that are progressively further from your host to see if any networking problems occur.
22.) traceroute is a useful troubleshooting tool because:
It reports each router that a packet passes through to a remote computer, along with the time needed to reach that router.
23.) If you cannot ping a host on your local network using that system's IP address, you probably wouldn't bother checking:
Whether you could ping that system using its domain name or host name.
24.) Which of the following is not included in the output of the traceroute command?
The size of the test packet sent by traceroute.
25.) A DHCP server can provide what information to a host on the network in response to a DHCP client request?
An IP address, a network mask, a gateway address, a DNS server address, and a host name, among other things.
SSH, the r-utilities, and Telnet. SSH is a more secure protocol.
2.) One advantage of Telnet is that:
It can be used on many different platforms, including Linux and Windows.
3.) Name three utilities that are part of the r-utilities and explain what each does.
There is rsh for executing a command on a remote host without actually logging on to the system, rcp which allows you to copy files between two hosts, and rlogin which lets you login to a remote system in a similar way to Telnet.
4.) The rcp program is able to copy files between:
Any two computers that are configure to use the r-utilities programs.
5.) Name the three types of authentication that SSH can use to connect to a remote system. Which is preferred as the most secure?
You can use the r-utilities, using passwords, or public key encryption. The public key encryption is the most secure.
6.) Which utility is used to prepare a set of keys needed to use public key encryption within SSH?
ssh-keygen
7.) Why might you need to use the -l option with the ssh command?
It tells you that you are wanting to access the user account that immediately follows the option.
8.) If you use the ssh command without first creating and storing a key pair on the remote host:
You are prompted for a password to aid authentication.
9.) If you have installed and configured r-utilities, then including a host and user name in your .rhosts file allows a person using the rcp command on another host to:
Copy files to or from your home directory without entering a password.
10.) SSH is commonly used in place of Telnet because:
SSH protocols use a more robust encryption algorithm than that used by Telnet.
11.) When using Telnet you might refer to VT100 because it is:
The most commonly used terminal emulation standard.
12.) Telnet is considered dangerous because:
It transmits data--including passwords--without encrypting them, so anyone on the network can see them by using special software.
13.) When using the wget command, you should include the http:// designation to download a Web page so that:
The program knows which protocol to use when accessing the server.
14.) Suppose you want to mirror a Web site to your local computer in order to study the information it contains. You intend to update the mirror once each month to view changes in the Web pages on the site. You are concerned that the Web site administrator will block access if he realizes you are mirroring the entire site instead of using a regular browser to access it. In order to reduce the chance that the wget program creates suspicion, you can:
Use the --random-wait option with wget.
15.) The rsync program is best suited for:
Synchronizing collections of files such as software development files.
16.) On a publicly available anonymous FTP server, the first level subdirectory that you should to to when locating files to download is virtually always:
/pub
17.) A graphical FTP client can be more convenient than a text-mode FTP client such as ncftp because:
The graphical program lets you see lists of files locally and remotely and drag and drop multiple files between systems.
18.) The ncftp package includes a utility that is similar in functionality to wget. This utility is called:
ncftpget
19.) If an IP address is not assigned explicitly when networking is configured, one must be obtained automatically from a server on the network using ________.
DHCP
20.) The process of resolving a domain name:
Determines the IP address associated with that domain name by contacting a DNS server.
21.) ping is used to test networking connections by:
Trying to contact systems that are progressively further from your host to see if any networking problems occur.
22.) traceroute is a useful troubleshooting tool because:
It reports each router that a packet passes through to a remote computer, along with the time needed to reach that router.
23.) If you cannot ping a host on your local network using that system's IP address, you probably wouldn't bother checking:
Whether you could ping that system using its domain name or host name.
24.) Which of the following is not included in the output of the traceroute command?
The size of the test packet sent by traceroute.
25.) A DHCP server can provide what information to a host on the network in response to a DHCP client request?
An IP address, a network mask, a gateway address, a DNS server address, and a host name, among other things.
Friday, March 6, 2009
Chapter 6 Review Questions
1.) The command ps -A xo comm displays the following information:
All processes running on the system, including those with no controlling terminal, with the command-line field displayed for each one.
2.) The _____ field in the ps command output defines how much cumulative CPU time a process has used since it was started.
TIME
3.) The CMDLINE field of the ps command output displays:
The command line used to start the process on each line.
4.) Which of the following commands is invalid if run by a regular user?
renice -10 1035
5.) Which of these programs does not allow you to change the nice level of a running program?
free
6.) To update the process displayed by the top command, you press which key?
spacebar
7.) Dynamically linked applications are preferred for their better memory usage unless:
The necessary libraries to run the application are not installed on the Linux system.
8.) Thrashing occurs when:
An excessive amount of information is moved to and from the swap partition in a short time.
9.) The command vmstat 4 does which of the following?
Displays continuous updates of the virtual memory status on a new line every four seconds.
10.) How can you switch between multiple virtual consoles in text and graphical environments?
In the graphical environment you press F1 through F6 to switch between the different consoles, and then F7 to return to the graphical desktop. In a text environment Ctrl+Alt+ to switch between the different consoles.
11.) Describe at least four fields of information provided by the command ps auxf.
The User field tells you which user is currently employing that process. The %mem field tells you the percentage of the memory that the process is using. The Start field tells you what day the process was started. The %cpu field tells you what percent of the processing power is being used by a process. The Command field tells you what the command line of that process is.
12.) By starting multiple jobs from one shell, you can:
Manage those jobs with the jobs, fg, and bg commands.
13.) Briefly explain the difference in time specification formats for the at and crontab commands.
With at you input the command and then you have the option of putting in a time from now whether it is hours or days away, or you have the option of entering a specific day. With the crontab command you input the minute, hour, date, month, and weekday using a * to designated whichever field you don't need to fill in.
14.) The background processes that manage commands submitted using at and cron are:
atd and crond
15.) When using the at command interactively to enter commands scheduled for futuer execution, you indicate that you have finished entering commands by pressing:
Ctrl+d
16.) The batch command is used to schedule jobs so that:
The system will not be overloaded with scheduled tasks.
17.) A simple method for root to schedule recurring system administration tasks is to:
Add a script to a directory such as /etc/cron.daily or /etc/cron.weekly
18.) The output of a cron job is normally sent via ____ to the user who submitted the cron job or to the user defined by the ____ variable within the file containing the cron job.
e-mail, MAILTO
19.) Name, in order from left to right, the fields of the crontab time specification, giving the range of valid numeric values for each.
Minute of the hour from 0-59, Hour of the day from 0-23, Day of the month from 0-31 depending on the month you are in, Month of the year from 0-12, and Day of the week from 0-7(0 and 7 are both Sunday).
20.) Output from a command executed as part of a cron job cannot be redirected to a file using standard redirection operators because the environment in which the cron job was created is unlikely to exist when the job is executed. True or False?
True
21.) The ____ file can include a user name in order to deny that user access to the crontab command.
/etc/cron.deny
22.) Name the two separate commands that can be used instead of at -l and at -d.
atq and atrm
23.) All process in Linux, except the init process (PID 1) are created:
When another process forks.
24.) A zombie process is one that:
Is no longer in existence, though the Linux kernel still maintains information as if it were.
25.) Describe why you should try SIGTERM before using SIGKILL.
SIGTERM requests that the process manually shuts itself down and allows it to save the current information while SIGKILL tells the kernel to shut the process down immediately which can cause you to lose what you are working on.
All processes running on the system, including those with no controlling terminal, with the command-line field displayed for each one.
2.) The _____ field in the ps command output defines how much cumulative CPU time a process has used since it was started.
TIME
3.) The CMDLINE field of the ps command output displays:
The command line used to start the process on each line.
4.) Which of the following commands is invalid if run by a regular user?
renice -10 1035
5.) Which of these programs does not allow you to change the nice level of a running program?
free
6.) To update the process displayed by the top command, you press which key?
spacebar
7.) Dynamically linked applications are preferred for their better memory usage unless:
The necessary libraries to run the application are not installed on the Linux system.
8.) Thrashing occurs when:
An excessive amount of information is moved to and from the swap partition in a short time.
9.) The command vmstat 4 does which of the following?
Displays continuous updates of the virtual memory status on a new line every four seconds.
10.) How can you switch between multiple virtual consoles in text and graphical environments?
In the graphical environment you press F1 through F6 to switch between the different consoles, and then F7 to return to the graphical desktop. In a text environment Ctrl+Alt+
11.) Describe at least four fields of information provided by the command ps auxf.
The User field tells you which user is currently employing that process. The %mem field tells you the percentage of the memory that the process is using. The Start field tells you what day the process was started. The %cpu field tells you what percent of the processing power is being used by a process. The Command field tells you what the command line of that process is.
12.) By starting multiple jobs from one shell, you can:
Manage those jobs with the jobs, fg, and bg commands.
13.) Briefly explain the difference in time specification formats for the at and crontab commands.
With at you input the command and then you have the option of putting in a time from now whether it is hours or days away, or you have the option of entering a specific day. With the crontab command you input the minute, hour, date, month, and weekday using a * to designated whichever field you don't need to fill in.
14.) The background processes that manage commands submitted using at and cron are:
atd and crond
15.) When using the at command interactively to enter commands scheduled for futuer execution, you indicate that you have finished entering commands by pressing:
Ctrl+d
16.) The batch command is used to schedule jobs so that:
The system will not be overloaded with scheduled tasks.
17.) A simple method for root to schedule recurring system administration tasks is to:
Add a script to a directory such as /etc/cron.daily or /etc/cron.weekly
18.) The output of a cron job is normally sent via ____ to the user who submitted the cron job or to the user defined by the ____ variable within the file containing the cron job.
e-mail, MAILTO
19.) Name, in order from left to right, the fields of the crontab time specification, giving the range of valid numeric values for each.
Minute of the hour from 0-59, Hour of the day from 0-23, Day of the month from 0-31 depending on the month you are in, Month of the year from 0-12, and Day of the week from 0-7(0 and 7 are both Sunday).
20.) Output from a command executed as part of a cron job cannot be redirected to a file using standard redirection operators because the environment in which the cron job was created is unlikely to exist when the job is executed. True or False?
True
21.) The ____ file can include a user name in order to deny that user access to the crontab command.
/etc/cron.deny
22.) Name the two separate commands that can be used instead of at -l and at -d.
atq and atrm
23.) All process in Linux, except the init process (PID 1) are created:
When another process forks.
24.) A zombie process is one that:
Is no longer in existence, though the Linux kernel still maintains information as if it were.
25.) Describe why you should try SIGTERM before using SIGKILL.
SIGTERM requests that the process manually shuts itself down and allows it to save the current information while SIGKILL tells the kernel to shut the process down immediately which can cause you to lose what you are working on.
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