lecture 2 linux basic commands,shell and make september 8, 2015 kyu ho park

Lecture 2Linux Basic Commands,Shell and

Make

September 8, 2015Kyu Ho Park

Computer Engineering Research Labora-tory

Linux Basics


root 계정 전환ubuntu@omap:~$ sudo passwd root[sudo] password for ubuntu: temppwdEnter new UNIX password: temppwd ( 또는 원하는 패스워드 )Retype new UNIX password: temppwd ( 또는 원하는 패스워드를 다시 입력 )passwd: password updated successfullyubuntu@omap:~$ su rootPassword: temppwd ( 또는 위에서 입력한 패스워드 )root@omap:/home/ubuntu#


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


Shell-command interpreter

‘User’LinuxLinux

Shell


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


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


Project1-Task1


Tree search

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$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

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Interactive program


Making a script executable


Shell script( commands in a file )


variables


Quoting


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

if[ -d $directory ] then --- fi


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 ----


‘if~fi’ control structure if condition then

statements else

statements fi


forSample script


for


while while condition do statements done


functions function( ) {

statements }


function example


Project 2 Simple C programing

Basic Linux System Callsopen(),read(),write(),lseek(),close()

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Basic Linux System Callsopen(),read(),write(),lseek(),close()

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open( ) #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-pa-

rameter 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}


read(), write() read()

#include <unistd.h>size_t read(int fildes, void *buf,

size_t nbytes);

write() #include <unistd.h>

size_t write(int fildes, const void *buf, size_t nbytes);

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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.

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rand( ) rand( )

#include <stdlib.h>#define RAND_MAX 0x7ff

rand() //it will generate a number of [0, 0x7ff]

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memalign() memalign() allocates size bytes and re-

turns a pointer to the allocated memory. The memory address will be a multiple of boundary, which must be a power of two.

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make and makefile


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


example/*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){

}


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


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

%makegcc –c main.cgcc –c test1.cgcc –c test2.cgcc –o test main.o test1.o test2.o


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


Macros in a makefile


LabelMakefile2:


make clean


Typical MACRO var.#Which compilerCC =gcc #Option flagsCFLAGS = -g –Wall#Program source filesSRCS = main.c test1.c test2.c#object filesOBJS#Library filesLIBS#Library directoriesLIBDIRS


Error


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


Kernel Compile1.Kernel Configuration to give the information of current H/W, Kernel, Network characteristics to the newly made kernel. -make config, make menuconfig, make xconfig2.Kernel compile -make bzImage or make zImage( for a small sized

kernel) - make( after Linux version 2.6)

3.Kernel install -make install

lecture 2 linux basic commands,shell and make september 8, 2015 kyu ho park

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