Lecture 2 Linux Basic Commands,Shell and Make September 8, 2015 Kyu Ho Park

Computer Engineering Research Laboratory Linux Basics

Computer Engineering Research Laboratory root 계정 전환 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 )

Computer Engineering Research Laboratory 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

Computer Engineering Research Laboratory Shell -command interpreter ‘User’ Linux Shell

Computer Engineering Research Laboratory 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

Computer Engineering Research Laboratory Shell Syntax  Variables  Conditions  Program control: if, elif, for, while, until, case  Functions  Lists

Computer Engineering Research Laboratory Project1-Task1

Computer Engineering Research Laboratory Tree search 9

Computer Engineering Research Laboratory $tree. ├── Algol │ ├── Ch1 │ │ ├── c1p1 │ │ ├── c1p1.c │ │ ├── c1p2 │ │ ├── c1p2.c │ │ ├── c1p3 │ │ ├── c1p3.c │ │ ├── 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

Computer Engineering Research Laboratory Interactive program

Computer Engineering Research Laboratory Making a script executable

Computer Engineering Research Laboratory Shell script( commands in a file )

Computer Engineering Research Laboratory variables

Computer Engineering Research Laboratory Quoting

Computer Engineering Research Laboratory if~fi  if [ -d $directory ]; then ---- fi  if[ -d $directory ] then --- fi

Computer Engineering Research Laboratory 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  ----

Computer Engineering Research Laboratory ‘if~fi’ control structure  if condition then statements else statements fi

Computer Engineering Research Laboratory forSample script

Computer Engineering Research Laboratory for

Computer Engineering Research Laboratory while  while condition do statements done

Computer Engineering Research Laboratory functions  function( ) { statements }

Computer Engineering Research Laboratory function example

Computer Engineering Research Laboratory Project 2 Simple C programing  Basic Linux System Calls open(),read(),write(),lseek(),close() 24

Computer Engineering Research Laboratory Basic Linux System Calls open(),read(),write(),lseek(),close() 25  open( ) #include 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}

Computer Engineering Research Laboratory read(), write()  read() #include size_t read(int fildes, void *buf, size_t nbytes);  write() #include size_t write(int fildes, const void *buf, size_t nbytes); 26

Computer Engineering Research Laboratory lseek()  lseek() #include 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. 27

Computer Engineering Research Laboratory rand( )  rand( ) #include #define RAND_MAX 0x7ff rand() //it will generate a number of [0, 0x7ff] 28

Computer Engineering Research Laboratory 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. 29

Computer Engineering Research Laboratory make and makefile

Computer Engineering Research Laboratory 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.

Computer Engineering Research Laboratory example /*file: main.c*/ #include #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) { }

Computer Engineering Research Laboratory Without ‘make’ %gcc –c main.c %gcc –c test1.c %gcc –c test2.c %gcc –o test main.o test1.o test2.o

Computer Engineering Research Laboratory 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

Computer Engineering Research Laboratory test2.c is modified %vi test2.c /*file:test2.c*/ #include void test2(void) { printf(“This is test2.c\n”); } %make gcc –c test2.c gcc -0 test main.o test1.o test2.o

Computer Engineering Research Laboratory Macros in a makefile

Computer Engineering Research Laboratory

Label Makefile2:

Computer Engineering Research Laboratory make clean

Computer Engineering Research Laboratory 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

Computer Engineering Research Laboratory

Error

Computer Engineering Research Laboratory 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

Computer Engineering Research Laboratory 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