1. Lecture 2 Linux Basic Commands,Shell and Make
September 6, 2016
Kyu Ho Park

2. Linux Basics

3. root 계정 전환 ubuntu@omap:~$ sudo passwd root
[sudo] password for ubuntu: temppwd
Enter new UNIX password: temppwd (또는 원하는 패스워드)
Retype new UNIX password: temppwd (또는 원하는 패스워드를 다시 입력)
passwd: password updated successfully
su root
Password: temppwd (또는 위에서 입력한 패스워드)

4. Linux commands File related:
ls , cd, mkdir, rm, df, du, mount, unmount, mkfs
touch, chmod, chown, tar, cp, mv,
Process related:
clear, whoami, whereis, su, pwd

5. Shell
-command interpreter ‘User’
Linux
Shell
Linux

6. Shell programming
-script : it is a file that contains shell command and it is a shell program. -Creating a Script
#!/bin/bash
# An example of a shell script that replaces the command ‘ls –l > output.txt’
ls –l > output.txt
exit 0

7. Shell Syntax Variables Conditions
Program control: if, elif, for, while, until, case
Functions
Lists

8. Project1-Task1

9. $tree . ├── Algol │ ├── Ch1 │ │ ├── c1p1 │ │ ├── c1p1.c │ │ ├── c1p2
│   │   ├── data
│   │   ├── data.txt
│   │   ├── ex03-01
│   │   ├── ex03-01.c
│   │   ├── ex04-01
│   │   ├── ex04-01.c
│   │   ├── ex10-01.c
│   │   ├── ex12-01c
│   │   ├── ex12-01c.c
│   │   ├── ex12-01s
│   │   ├── ex12-01s.c
│   │   ├── fifo
│   │   ├── honor
│   │   ├── honor.c
│   │   ├── newdata1.txt
│   │   ├── newdata.txt
│   │   ├── newname.txt
│   │   ├── test.txt
│   │   └── test.txt.soft -> test.txt
│   ├── Ch2
│   │   ├── mem-region
│   │   └── mem-region.c
│   ├── fileTest
│   │   └── data
│   ├── infile
│   ├── outfile
│   ├── pipewr
│   ├── pipewr.c
│   ├── testWelcom
│   ├── testWelcom.c
│   └── testWelcom.s
├── clone
├── clone.c
├── DDriver
│   ├── Makefile
│   ├── P301
│   ├── P301.c
│   ├── P303
│   ├── P303.c
│   └── test.c
├── express
├── fork
├── fork.c
├── sh1
├── shQuot
├── traverse
└── treesearch

10. Tree search

11. Interactive program

12. Making a script executable

13. Shell script( commands in a file )

14. variables

15. Quoting

16. if~fi
if [ -d $directory ]; then
---- fi
if[ -d $directory ]
then
---

17. if~fi -d file //True if the file is a directory
-e file //True if the file exists
-f file //True if the file is a regular file
-x file //True if the file is executable
----

18. ‘if~fi’ control structure
if condition
then
statements
else fi

19. forSample script

20. for

21. while
while condition do
statements
done

22. functions
function( ) {
statements }

23. function example

24. Task 2 Simple C programing
Basic Linux System Calls open(),read(),write(),lseek(),close()

25. Basic Linux System Calls open(),read(),write(),lseek(),close()
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
int open(const char *path, int oflags);
int open(const char *path, int oflags, mode_t mode);
Open with oflag=O_CREATE, we must use the three-parameter form with mode.
mode:
S_IRUSER: Read permission, owner
S_IWGRP:Write permission, group
S_IXOTH: Execute permission, others
oflag={O_RDONLY,O_WRONLY,O_RDWR} ored with{O_APPEND, O_TRUNC, O_CREATE, O_EXCL}

26. read(), write() read() #include <unistd.h>
size_t read(int fildes, void *buf, size_t nbytes);
write()
size_t write(int fildes, const void *buf, size_t nbytes);

27. lseek() lseek() #include <unistd.h> #include <sys/types.h>
off_t lseek(int fildes, off_t offset, int whence);
//lseek() system call sets the read/write pointer of a file descriptor fildes.
whence:
SEEK_SET: offset is an absolute position,
SEEK_CUR:offset is relative to the current position,
SEEK_END:offset is relative to the end of the file.

28. rand( ) rand( ) #include <stdlib.h> #define RAND_MAX 0x7ff
rand() //it will generate a number of [0, 0x7ff]

29. memalign()
memalign() allocates size bytes and returns a pointer to the allocated memory. The memory address will be a multiple of boundary, which must be a power of two.

30. make and makefile

31. make [-f filename]
% make [-f filename] - if you don’t use –f option, the default file is Makefile or makefile. -if there are Makefile and makefile at the same time, Makefile will be selected.

32. example /*file: test.h*/
/*file: main.c*/ #include <stdio.h> #include “test.h” int main(void) { test1(); test2(); printf(“Hello world!\n”); return 0; }
/*file: test.h*/
void test1(void);
void test2(void);
/*file: test1.c*/
void test1(void) { }
/*file: test2.c*/
void test2(void)

33. Without ‘make’
%gcc –c main.c %gcc –c test1.c %gcc –c test2.c %gcc –o test main.o test1.o test2.o

34. With ‘make’
-Makefile %vi Makefile test : main.o test1.o test2.o gcc –o test main.o test1.o test2.o main.o : test.h main.c gcc –c main.c test1.o : test.h test1.c gcc –c test1.c test2.o : test.h test2.c gcc –c test2.c
%make
gcc –c main.c
gcc –c test1.c
gcc –c test2.c
gcc –o test main.o test1.o test2.o

35. test2.c is modified
%vi test2.c /*file:test2.c*/ #include <stdio.h> void test2(void) { printf(“This is test2.c\n”); } %make gcc –c test2.c gcc -0 test main.o test1.o test2.o

36. Macros in a makefile

38. Label
Makefile2:

39. make clean

40. Typical MACRO var.
#Which compiler CC =gcc #Option flags CFLAGS = -g –Wall #Program source files SRCS = main.c test1.c test2.c #object files OBJS #Library files LIBS #Library directories LIBDIRS

42. Implicit rule
#Name of the current target $? # List of prerequisites(files the target depends on) #changed more recently than the current target $< #Name of the current prerequisite $* #Name of the prerequisite, without any suffix

43. Kernel Compile
1.Kernel Configuration to give the information of current H/W, Kernel, Network characteristics to the newly made kernel. -make config, make menuconfig, make xconfig 2.Kernel compile -make bzImage or make zImage( for a small sized kernel) - make( after Linux version 2.6) 3.Kernel install -make install