vickad lab1 submission

ANSWERS.md

@@ -19,111 +19,114 @@ Please use [markdown](https://help.github.com/articles/markdown-basics) formatin
 
 Make another directory inside the `unixstuff` directory called `backups`
 
-**Answer:** *YOUR ANSWER HERE*
+cd unixstuff, mdir backups, (, indicates return press)
 
 ###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*
+cd NAME gets you to directory NAME, ls lists all files and directory in the current working directory, pwd shows me where i am working
 
 ###Exercise 2a
 
 Create a backup of your `science.txt` file by copying it to a file called `science.bak`
 
-**Answer:** *YOUR ANSWER HERE*
+cp science.txt science.bak
 
 ###Exercise 2b
 
 Create a directory called `tempstuff` using `mkdir`, then remove it using the `rmdir` command.
 
-**Answer:** *YOUR ANSWER HERE*
+mkdir tempstuff, 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*
+cat > list2, orange, plum, mango, grapefruit, (ctrl+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*
+cat list1 list2 | grep p | sort
 
 ###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*
+chmod go-rwx backups, chmod a+rw science.txt
 
 ##Shell questions
 
 1. What option with the command `rm` is required to remove a directory?
-  - **Answer:** *YOUR ANSWER HERE*
+  - it has to be empty
 1. What is the command used to display the manual pages for any command?
-  - **Answer:** *YOUR ANSWER HERE*
+  man command
 1. What command will show the first 5 lines of an input file?
-  - **Answer:** *YOUR ANSWER HERE*
+  - head -5 filename
 1. What command can be used to rename a file?
-  - **Answer:** *YOUR ANSWER HERE*
+  - mv currentfilename newfilename
 1. What option can we given to `ls` to show the hidden files?
-  - **Answer:** *YOUR ANSWER HERE*
+  - ls -a
 1. What will the command `cat -n file` do?
-  - **Answer:** *YOUR ANSWER HERE*
+  - displays content inside the file file and with line numbers
 1. What will the command `echo -n hello` do?
-  - **Answer:** *YOUR ANSWER HERE*
+  - it adds "hello" to the start of your username, so when you write next time it says helloUsername@computername:
 1. What command will display s list of the users who currently logged in in the system?
-  - **Answer:** *YOUR ANSWER HERE*
+  - who
 1. How do you change password on your account?
-  - **Answer:** *YOUR ANSWER HERE*
+  - passwd enter oldpassword enter newpassword enter newpassword enter (enter = enterbutton)
 1. How can you list a file in reverse order?
-  - **Answer:** *YOUR ANSWER HERE*
+  - ls -r
 1. What does the `less` command do?
-  - **Answer:** *YOUR ANSWER HERE*
+  - writes out content of a file one page at a time
 1. With `less` how do you navigate?
-  - **Answer:** *YOUR ANSWER HERE*
+  - space bar for another page and q for quit
 1. What command will display the running processes of the current user?
-  - **Answer:** *YOUR ANSWER HERE*
+  - ps
 1. What command can be used to find the process(es) consuming the most CPU?
-  - **Answer:** *YOUR ANSWER HERE*
+  - sleep 100 + C (control c), kill PID_number
 
 ##vi questions
 1. How do we save a file in `vi` and continue working?
-  - **Answer:** *YOUR ANSWER HERE*
+  - :w filename
 1. What command/key is used to start entering text?
-  - **Answer:** *YOUR ANSWER HERE*
+  - "i"for insert, escape for going back to command
 1. What are the different modes the editor can be in?
-  - **Answer:** *YOUR ANSWER HERE*
+  - insert and command
 1. What command can be used to place the cursor at the beginning of line 4?
-  - **Answer:** *YOUR ANSWER HERE*
+  - :# 4 #
 1. What will `dd` command do (in command-mode)?
-  - **Answer:** *YOUR ANSWER HERE*
+  - deletes the line that the cursor is on
 1. How do you undo the most recent changes?
-  - **Answer:** *YOUR ANSWER HERE*
+  - "u" for undo
 1. How do you move back one word?
-  - **Answer:** *YOUR ANSWER HERE*
+  - "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*
+  - gcc -c hello.c -o hello.o, you dont specify the exe filename and hello.o isnt runnable
 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*
+  - gcc hello.c -D DEBUG hello -o (debug on) gcc hello.c hello -o (debug off).  For the other one we can change it off by setting int debug = 0; and take debug on by typing in 1 instead of 0 and compile and runt the program.
 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*
+  - the first one you can run just by taking in the -D DEBUG false or true when you compile, the other one is a little more work since you need to change int debug which is inside the c file. 
 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*
+  - gcc hello.c -o hello -Wl,-Map=output.map, linkeren 
 1. What is the content of each of the sections in a *map* file. Explain briefly.
-  - **Answer:** *YOUR ANSWER HERE*
+  - initialized (int somthing set to somthing that is not 0) plomme
+  - uninitialized (int somthing set to 0) eple
+  - read only (int const) appelsin
 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*
+  - int eple =0;(.bss) int plomme = 1;(.data) const int appelsin = 2;(.rodata)
 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*
+  - (gcc hello.c -S -o hello.assembly)  
+  - assembly for float: movss and mulss, for double movsd and mulsd, they have different type of ssembly but the start of the assembly are thesame (mov x3 and mul x1)
 1. How does `make` know if a file must be recompiled?
   - **Answer:** *YOUR ANSWER HERE*
 1. Provide a `make` command to use a file named `mymakefile` instead of the default `makefile`.

hello.c

@@ -0,0 +1,30 @@
+
+#include <stdio.h>
+int debug = 1;
+int eple =0;
+int plomme = 1;
+const int appelsin = 2;
+
+int main(void)
+
+{
+	if ( debug )
+	{
+	printf("Debugging\n");
+	}
+	printf("Hello, world!\n");
+	return 0;
+
+}
+
+float fmultiply(float a, float b){
+	return a*b;}
+
+
+double dmultiply(double a, double b){
+	return a*b;
+
+}
+
+
+