Delarock lab1 submission

ANSWERS.md

@@ -19,128 +19,236 @@ Please use [markdown](https://help.github.com/articles/markdown-basics) formatin
 
 Make another directory inside the `unixstuff` directory called `backups`
 
-**Answer:** *YOUR ANSWER HERE*
+**Answer:** 
+NB! Lab er utført på VM med Ubuntu, med brukernavn linus. Jeg får ikke enkelt linjeskift til å fungere via MarkdownPad 2(kun dobbelt), så teksten kan være litt uoversiktelig. Det er imidlertid korrekt i "koden".
+
+`mkdir unixstuff, cd unixstuff, mkdir backups`
+
 
 ###Exercise 1b
 
 Use the commands `cd`, `ls` and `pwd` to explore the file system.
 
 (Remember, if you get lost, type `cd` by itself to return to your home-directory)
 
-**Answer:** *YOUR ANSWER HERE*
+**Answer:** 
+`cd, pwd, ls -a, cd Documents, cd .., cd Videos, pwd ->
+ /home/linus/Videos	`		
 
 ###Exercise 2a
 
 Create a backup of your `science.txt` file by copying it to a file called `science.bak`
 
-**Answer:** *YOUR ANSWER HERE*
+**Answer:** 
+`touch science.txt
+cp science.txt ./backups`
 
 ###Exercise 2b
 
 Create a directory called `tempstuff` using `mkdir`, then remove it using the `rmdir` command.
 
-**Answer:** *YOUR ANSWER HERE*
+**Answer:**
+`mkdir tempstuff
+ls
+rmdir tempstuff`
 
 ###Exercise 3a
 
 Using the above method, create another file called `list2` containing the following fruit: orange, plum, mango, grapefruit. Read the contents of `list2`.
 
-**Answer:** *YOUR ANSWER HERE*
+**Answer:** 
+`cat > list2
+orange
+plum
+mango
+grapefruit
+^D
+cat list2`
 
 ###Exercise 3b
 
 Using pipes, display all lines of `list1` and `list2` containing the letter 'p', and sort the result.
 
-**Answer:** *YOUR ANSWER HERE*
+**Answer:**
+`sort biglist | grep p`
+apple
+grape
+grapefruit
+peach
+pear
+plum
 
 ###Exercise 5a
 
 Try changing access permissions on the file `science.txt` and on the directory `backups`.
 
 Use `ls -l` to check that the permissions have changed.
 
-**Answer:** *YOUR ANSWER HERE*
+**Answer:** 
+`chmod a+rwx science.txt2
+chmod a+rwx backups
+ls -l`
+d rwx rwx rwx linus linus 4096 2014-08-31 14.30 backups
+- rw- r-- r-- linus linus   66 2014-08-31 14.38 biglist
+- rw- r-- r-- linus linus   37 2014-08-31 14.37 list1
+- rw- r-- r-- linus linus   29 2014-08-31 14.35 list2
+- rwx rwx rwx linus linus    0 2014-08-31 14.29 science.txt
+- rw- r-- r-- linus linus   66 2014-08-31 14.39 slist
 
 ##Shell questions
 
 1. What option with the command `rm` is required to remove a directory?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** rmdir
 1. What is the command used to display the manual pages for any command?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** man _command_
 1. What command will show the first 5 lines of an input file?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** head -5
 1. What command can be used to rename a file?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** mv _oldName_ _newName_
 1. What option can we given to `ls` to show the hidden files?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** -a
 1. What will the command `cat -n file` do?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** Gives numbers to all lines
 1. What will the command `echo -n hello` do?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** Nothing, as the -n indicates that it should not echo the next line
 1. What command will display s list of the users who currently logged in in the system?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** who
 1. How do you change password on your account?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** passwd 
 1. How can you list a file in reverse order?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** sort -r
 1. What does the `less` command do?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** Writes content to screen one page at a time
 1. With `less` how do you navigate?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** [Space] to continue, [q] to quit
 1. What command will display the running processes of the current user?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** ps
 1. What command can be used to find the process(es) consuming the most CPU?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** ps --sort=-pid (given that pid is process consumtion, which it might not be)
 
 ##vi questions
 1. How do we save a file in `vi` and continue working?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** `:w`
 1. What command/key is used to start entering text?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** `i` for Insert
 1. What are the different modes the editor can be in?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** Command and Insert mode
 1. What command can be used to place the cursor at the beginning of line 4?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** `:4`
 1. What will `dd` command do (in command-mode)?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** Delete the current line
 1. How do you undo the most recent changes?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** `u`
 1. How do you move back one word?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** `b`
 
 ##The C Language and Make tool Questions
 
 1. How do you use `gcc` to only produce the `.o` file?  What is the difference between generating only the `.o` file, and building the `hello` executable done in the previous compilation above?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** `gcc hello.c -c`
+				.o is an Object file and not an executable file.
 1. Give the command for compiling with `debug` enabled instead of normal compilation for the two examples shown in Listing 2 and Listing 3. Explain how to turn debugging on/off for the two cases.
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** To compile for debugging, use -g. This will create a a.out file.
 1. Give a brief pros and cons discussion for the two methods to add debug code shown in Listing 2 and Listing 3.
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** In theory, the first example should always show the debug code when run in gdc mode couse it looks to see if DEBUG is defined (which it might not be now I guess), while the second one will only show when debug is set to 1, which it is not currently. An advantage of the first way to do it is that it is much easier to find and remove debug code when needed, while an advantage of the second way is that you can debug part of the program at a time. However, I was not able to get the debug comment to print, no matter what i did, using gcc and gdb. Ideally i would like a resource that describes this in more details, as I could not find anything regarding this on isLearning, gitHub or in the course book. That also goes for the rest of this and the next task (although to be fair, make was briefly mentioned on a slideshow). 
 1. Provide the command for generating the *map* file. Which of the `gcc` tools is responsible for producing a *map* file?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** After googling this for quite some time, the best I can say is that it's possibly something with "-W1,-MAP=output.map", but I am not able to make it work as gcc does not recognise the commands. Some examples would be welcome. Edit: After the next task, I was able to create a .map file. However, as I tried several different commands, I do not know which one worked. Possibly -m?
 1. What is the content of each of the sections in a *map* file. Explain briefly.
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** 
+  The address to the memory allocation of:
+  .txt -> The code
+  .data -> Initialized global and static variables
+  .bss -> Uninitialized global and static variables
+  .rodata -> Constants and strings 
 1. Rewrite `hello.c` to produce entries in the *map* file for `.data`, `.bss`, and `.rodata`. Hint: This can be done by adding one variable for each type to the file.
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** Done
 1. Add the following function to `hello.c`: `double multiply(double x1, double x2)`, which returns `x1*x2`. Use `gcc` to generate an assembly code listing for the program, and examine the assembly code. What assembly instructions are used to do this? Repeat this task, but now replace `double` with `float`. Explain!
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** The assembly instructions looks to be the following:
+`.cfi_startproc
+pushq %rbp
+.cfi_def_cfa_offset 16
+movq %rsp, %rbp
+.cfi_offset 6, -16
+.cfi_def_cfa_register 6
+movsd %xmm0, -8(%rbp)
+movsd %xmm1, -16(%rbp)
+movsd -8(%rbp), %xmm0
+mulsd -16(%rbp), %xmm0
+leave
+ret
+.cfi_endproc`
+
+After changing double with float, lines 7-10 changed to:
+`movss %xmm0, -4(%rbp)
+movss %xmm1, -8(%rbp)
+movss -4(%rbp), %xmm0
+mulss -8(%rbp), %xmm0
+`
+So the "d" is changed to "s", and the number value is halved.
+
+
 1. How does `make` know if a file must be recompiled?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** The makefile indicated what files make should look at, and make checkes the last change date for them compaired to last compile.
 1. Provide a `make` command to use a file named `mymakefile` instead of the default `makefile`.
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** `make -f mymakefile`
 1. How do you implement an *include guard*, and why is it needed?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** You implement include guard using #ifndef. Include guard is needed to avoid double inclusion, that can happen with parent and child files.
 
 ##Library Task
 
 Insert your code between the brackets `{}`:
 
     void main( int argc, char *argv[] )
 	{
+		/* I do not know C, but I am somewhat familiar with C# and have read the C introduction ppt, so hopefully I am close. I was not able to run this program, so I know it is not correct. */
+
+		table intTable[argc][argc];
+		for (i = 0, i < argc, i++)
+		{
+			for (j = 0, j < argc, j++)
+			{
+				intTable[i][j] = rand()%(MAX-MIN)+MIN;
+			}
+		}
+		int tableSum = lib1.tab_sort_sum(intTable, argc);
+		for (i = 0, i < argc, i++)
+		{
+			for (j = 0, j < argc, j++)
+			{
+				printf(intTable[i][j] + "\n");
+			}
+		}
+		printf(tableSum); 
+		return 0;
     }
 
 	double tab_sort_sum( double *tab, int tab_size )
 	{
+		//I assume *tab is the table, as the table is needed as input to sort it
+		int tempInt = 0;
+		int currentInt = 0;
+		int = sum;
+
+		for (i = 0, i < tab_size-1, i++)
+		{
+			for (j = 0, j < tab_size-1, j++)
+			{
+				currentInt = *tab[i][j];
+				sum =+ currentInt;
+				for (k = 0, k =< i, k++;)
+				{
+					for (l = 0, l =< j, l++;)
+					{
+						if(currentInt > *tab[k][l])
+						tempInt = *tab[k][l];
+						*tab[k][l] = currentInt;
+						*tab[i][j] = tempInt;
+					}
+				}
+
+			}
+		}
+		return sum, *tab;
 	}