Unix 1

Regd.No: 101FD01001 Page No: 1 Class: II MCA

VIGNAN UNIVERSITY, VadlamudiDEPARTMENT OF MCA

SESSION 1 :

A) LOG INTO THE SYSTEM:

$Enter User Name: MCAVU1Enter Password: MCAVU001

B) USE VI EDITOR TO CREATE A FILE CALLED MYTEXT.TXT WHICH CONTAINS SOME TEXT:

STEP 1: $VI mytext.txt and press ‘I’ to enter into INSERT mode

STEP 2: TYPE SOME TEXT AS FOLLOWS:

Welcome to UNIX, the open operating system. UNIX is found on virtually all computer hardware in use today. In fact, its very pervasiveness is most likely the reason you are starting to explore its capabilities.

C) CORRECT TYPING ERRORS DURING CREATION:

Correct typing errors if any in the text by moving the cursor around the text.The following cursor movement commands help in moving the cursor around the file.

COMMAND FUNCTIONh,backspace Moves the cursor one character to the leftL,spacebar Moves the cursor one character to the right

0 Moves the cursor to the beginning of the current line

$ Moves the cursor to the end of the current linek, Moves the cursor one line upj Moves the cursor one line down- Moves the cursor to the beginning of the previous

line+,return Moves the cursor to the beginning of the next line

D) SAVE THE FILE:

Press ‘ESC’ to exit the INSERT mode and enter into command mode. Now type ‘: w’ and press enter to save the file. Type ‘CTRL+Z’ to exit the VI editor.E) LOGOUT OF THE SYSTEM:



Type ’LOGOUT’ to exit the UNIX editor.

SESSION 2:A) LOG INTO THE SYSTEM:

$Enter User Name: MCAVU1Enter Password: MCAVU001

B) OPEN THE FILE CREATED IN SESSION 1:$ VI mytext.txt (Or)$ Cat mytext.txt

C) ADD SOME TEXT:

Press ‘I’ to enter into the INSERT mode.Append some text as follows:Welcome to UNIX, the open operating system. UNIX is found on virtually all computer hardware in use today. In fact, its very pervasiveness is most likely the reason you are starting to explore its capabilities.This chapter introduces you to the UNIX environment. After providing a basic understanding of its environment, we show you how to access a UNIX system and present its basic structure and some common commands.Press ‘ESC’ to exit the insert mode and type ‘: q’ save the file and exit the VI editor.The following help us in adding text to a file.

COMMAND FUNCTIONi Inserts text before the current character.I Inserts text at the beginning of the current line.a Appends text after the current character.A Appends text at the end of the current line.o Opens an empty text line for new text after the

current lineO Opens an empty text line for new text before the

current line

MAKE A DIRECTORY:

The following is the command to make a directory.$mkdir unixCOPYING A FILE: we use ‘cp’ command to copy files.



$cp myfile.txt unix

MOVING A FILE:

A file can be moved from one location to another using the ‘mv’ command.$mv /home/mcavu6/unix/myfile.txt /home/mcavu6/labThe above command moves a file named ‘myfile.txt’ from unix directory to lab directory.We use the same command to rename a file.

LIST DIRECTORY:

The list (ls) command lists the contents in a directory.Depending on the options used, it can list files, directories or subdirectories.

F) SAVE THE CHANGES:

Press ‘ESC’ to exit the insert mode and type ‘: q’ save the file and exit the VI editor.

G) LOGOUT OF THE SYSTEM:

Type ’LOGOUT’ to exit the UNIX editor.



SESSION:-3

Text Processing Commands

WC: (Word Count)

This command gives us about word count of a given files. This also gives the count of characters and the lines in the given file:

Syntax:Wc –l file name -- gives us about lines count in the fileWc –c filename -- gives us about characters count in a

file Wc –w filename -- gives us about words count in a

files

OD:Dump files in octal and other formats.

Syntax:Od [option]… [FILE]….Od [-abcdfilosx]… [FILE] [[+]OFFSET[.][b]]Od –traditional [option]… [FILE] [[+]OFFSET[.][b]

[+][LABEL][.][b]]This command writes an unambiguous representation, octal bytes by default, of FILE to standard output. With more than one FILE argument, concatenate them in the listed order to form the input. With no FILE, or when FILE is -, read standard output.

SORT:Sorts the lines of the text file.

Syntax:Sort [option]… [file]….

Write sorted concatenation of all FILES to standard output.-b : ignore leading blanks-d : consider only blanks and alphanumeric characters-f : fold lower case to upper case characters-n : compare according to string numerical value-R : sort by random hash of keys.TAIL:-This command gives the last 10 lines in a given file

Syntax:Tail filenameTail -1filename

By executing above command it displays the last line of a given file



HEAD:-This command displays first 10 lines in a file

Syntax:Head filenameHead -2 filename

The above command gives first 2 lines in the given file.

UNIQ:This command displays uniq lines of the given files. That is successive lines of a file are same then they will be removed. By default output will be on to the screen. This can also be used to removed the empty lines from a given file.

The useful –c option prefixes each line of the input file with its number of occurrences.Syntax:

Uniq -c filenameGREP:This command displays the lines containing the given search option.

Syntax:-Grep option filename.

Here “option” means the words in the file name.

DIFF:-This is used to compare the contents of two files in general

Syntax:Diff file1 file2.

If the content of file1 and file2 is same it displays nothing.CMP:The cmp utility compares two files of any type and writes the results to the standard output. By default, cmp is silent if the files are same: if they differ, the byte and line number at which th first difference is occurred is reported.

Syntax:Cmp file1 file2

COMM:Comm. –compare two sorted files line by line

Syntax:Comm file1 file2

CUT:This command displays the word in the line by giving the position of the character in each line.

Syntax:Cut position filenameCut –f1,3 filename

This displays the 1 and 3rd word of each line in the filename.



PASTE:This is used to join the files vertically.

Syntax:Paste file1 file2 > destination file.

By opening the destination file using the cat command the result is displayed.

DISK & BACKUP UTILITIES

DF:This command displays details about the each of the mounted partition, percentage of free ness, percentage of occupation etc.

DU:

This command displays disk usage(usually in multiples of 1K BLOCKS). DU command without any argument displays disk usage of all files, subdirectories of current corking directory.

Syntax:Du directoryname

This displays disk usage of all files sub-directories of the given directory.

WHO:

This displays details about the user such as user name, terminal on which working and since when they are working.

TAR:

This command is used to join a group of files and prepare a archive file. Tar –cvf a.tar directoryname or filenameThis command creates a archive file a.tar by joining the given file or files in the given directory. Tar –cvZf a.tZ directoryname or filename This command creates compressed tar archive.

Tar –cvzf a.tgz directoryname or filenameThis command creates gzipped tar archive.

Tar –xvf a.tarThis command extracts all files from the archive.

Tar –xvzf a.tzThis command extracts all files from the compressed archive.

Tar –xvzf a.tgz



This command extracts all files from the gzipped archive.

CPIO:

This is also used for backup purpose. Normally this command requires list of filename asinput and the results archive file which appears on the standard output.

Ls | cpio –o > archivefilenameThe above command creates archive having all the files of current directory.

Cpio –I abc <archivefilenameThis command restores all the files from the archive file.

Cpio –I “”*.c <archivefilenameThis command restores all the files with extension c from the archivefile.We can create the archive on the tapes or other devices also.

Find . –ctime 2 –print |cpio –ov > /dev/rmt 0

This command creates backup file on magnetic tape rmt 0 and stores all the files which are created in the recent 2 days.

PS:

Report a snapshot of the current process.Syntax:

Ps[option]Ps displays information about a selection of the active process. If you want to repetitive update of the selection and the displayed information, use top instead.This version of ps accepts several kinds of options:

1 Unix options, which may be grouped and must be preceded by a dash.2 Bsd options, which may be grouped and must not be used with a dash.3 Gnu long options, which are preceded by two dashes.

Options of different types may be freely mixed, but conflicts can appear. There are some synonymous options, which are functionally identical, due to the many standards and ps implementations that this ps is compatible with.



SESSION-4

1) WRITE A SHELL SCRIPT TO GENERATE A MULTIPLICATION TABLE TO GENERATE MULTIPLICATION TABLE

Program:

#To generate a multiplication tableEcho, "Enter the number"Read ni=1While [ $i -le 10 ]dor=èxpr $n \* $iècho $n x $i = $ri=èxpr $i + 1`done

Out put :

[mca49@MCA ~]$ vi aaa1.sh[mca49@MCA ~]$ chmod u+x aaa1.sh [mca49@MCA ~]$ ./aaa1.shenter the number55 x 1 = 55 x 2 = 105 x 3 = 155 x 4 = 205 x 5 = 255 x 6 = 305 x 7 = 355 x 8 = 405 x 9 = 455 x 10 = 50



2) WRITE A SHELL SCRIPT THAT COPIES MULTIPLE FILES IN A DIRECTORY

Aim : to write a shell script that copies multiple files in a directory

Program :

#usage mul files <filename>echo "enter directory name into which files should be copied"read dirnamefor file in $*docp $* $dirnamedone

Output :

[mca49@MCA ~]$ vi unix3.sh[mca49@MCA ~]$ chmod u+x unix3.sh[mca49@MCA ~]$ ./unix3.sh [mca49@MCA ~]$ ./unix3.sh unix2.sh unix3.shenter directory name into which files should be copiedlab170908[mca49@MCA ~]$ ls lab170908unix2.sh unix3.sh



3) Write a shell script that counts the number of lines and words present in a given program .

Aim: To write a shell program that copies multiple files to a directory

Program:

#to count the no of lines,words in a given fileecho "enter a filename to count the lines and words"read filenameecho "the no of lines in a given filename are"cat $filename |wc -lecho "the no of words in a given file are"cat $filename |wc –w

Out put :[mca49@MCA ~]$ vi unix2.sh[mca49@MCA ~]$ chmod u+x unix2.sh[mca49@MCA ~]$ ./unix2.shenter a filename to count the lines and wordslab14.cthe no of lines in a given filename are37the no of words in a given file are108



4) Write a shell script that displays the list of all files in the given directory

Aim: To display the list of files in the given directory

Program:

# to display the files in directoryecho " enter the directory name "read dirnamels $dirname

Out put :

[mca49@MCA ~]$ vi unix4.sh[mca49@MCA ~]$ chmod u+x unix4.sh[mca49@MCA ~]$ ./unix4.sh enter the directory namelab100908[mca49@MCA ~]$ ls lab100908[mca49@MCA ~]$ ./unix4.sh enter the directory namelab170908unix2.sh unix3.sh



5) WRITE A SHELL SCRIPT THAT ADDS, SUBSTRACT,MULTIPLIES, AND DIVIDES THE TWO GIVEN INTEGERS.THERE ARE TWO DIVISION OPTIONS : ONE RETURNS THE QUOTIENT AND THE OTHER RETURNS REMINDER.THE SCRIPT REQUIRES 3 ARGUMENTS : THE OPERATION TO BE USED AND TWO INTEGERS NUMBERS. THE OPTIONS ARE ADD(-A) , SUBSTRACT (-S) MULTIPLY (-M) , QUOTIENT(-C) AND REMAINDER(-R).

Aim : To perform Airthematic operations

Program:

#to perform artithematic operationsecho "enter the two numbers"read a becho "enter ur choice"echo "-a.addition"echo "-s.subtraction"echo "-m.multiplication"echo "-c .quotient"echo "-r remainder"read opcase $op in-a ) r=èxpr $a + $b` echo "the addition value is $r" ;;-s ) r=èxpr $a - $b` echo "the subtraction value is $r" ;;-m ) r=èxpr $a \* $b` echo "the multiplication value is $r" ;;-c ) r=èxpr $a / $b` echo "the quotient is $r"



;;-r ) r=èxpr $a % $b` echo "the remainder is $r" ;;

*) echo "not a valid operator" ;;

esac

Out put:

[mca49@MCA ~]$ vi unix5.sh [mca49@MCA ~]$ chmod u+x unix5.sh[mca49@MCA ~]$ ./unix5.shenter the two numbers10 20enter ur choice-a.addition-s.subtraction-m.multiplication-c .quotient-r remainder-athe addition value is 30[mca49@MCA ~]$ ./unix5.shenter the two numbers10 20enter ur choice-a.addition-s.subtraction-m.multiplication-c .quotient-r remainder-rthe remainder is 10



6. WRITE A SHELL SCRIPT TO REVERSE THE ROWS AND COLUMNS OF A MATRIX.

Aim: To reverse the rows and columns of a matrix

Program :echo "enter the size of matrix:"read rread cecho "enter elements:"i=0while [ $i -lt $r ]doj=0while [ $j -lt $c ]doread a$i$jj=èxpr $j + 1`donei=èxpr $i + 1`doneecho "the transpose of matrix is:"i=0while [ $i -lt $c ]doj=0while [ $j -lt $r ]doecho ""$[a$j$i]j=èxpr $j + 1`donei=èxpr $i + 1`done



Output:

[mca49@MCA ~]$ vi unix6.sh[mca49@MCA ~]$ chmod u+x unix6.sh[mca49@MCA ~]$ ./unix6.shenter the size of matrix:22enter elements:1234the transpose of matrix is:1324



SESSION-5

7) IMPLEMENT IN C CAT UNIX COMMAND USING SYSTEM CALLS

Aim : To implement cat command

Program :

#include<stdlib.h>#include<stdio.h>#include<fcntl.h>#include<unistd.h>#include<sys/stat.h>#include<sys/types.h>int main( int argc,char *argv[] ){int f=0,n;char m[80];struct stat s;if(argc!=2){printf("mismatch argument");exit(1);}if(access(argv[1],F_OK)){printf("file exits");exit(1);}if(stat(argv[1],&s)<0){printf("stat error");exit(1);}if(S_ISREG(s.st_mode)<0){printf("not a regular file");exit(1);



}if(geteuid()==s.st_uid)if(s.st_mode&S_IRUSR)f=1;else if(getegid()==s.st_gid)if(s.st_mode &S_IRGRP)f=1;

else if(s.st_mode&S_IROTH)f=1;

if(!f){printf("permission denied");exit(1);}f=open(argv[1],O_RDONLY);while((n=read(f,m,80))>0)write(1,m,n);printf("\n");}

Out put :

[mca49@MCA ~]$ cc unix7.shcc: unix7.sh: No such file or directorycc: no input files[mca49@MCA ~]$ cc unix7.c[mca49@MCA ~]$ ./a.out unix2.sh#to count the no of lines,words in a given fileecho "enter a filename to count the lines and words"read filenameecho "the no of lines in a given filename are"cat $filename |wc -lecho "the no of words in a given file are"cat $filename |wc -w



8) WRITE A C PROGRAM THAT ILLUSTRATES HOW TO EXECUTE TWO COMMANDS CONCURRENTLY WITH A COMMAND PIPE.Aim: To execute two commands concurrently with a command pipeProgram:#include<stdio.h>#include<stdlib.h>#include<unistd.h>int main(){ int pfds[2]; pipe(pfds); if(!fork()) { close(1); dup(pfds[1]); close(pfds[0]); execlp("ls","ls", NULL); } else { close(0); dup(pfds[0]); close(pfds[1]); execlp("wc","wc","-l", NULL); }}

output:[mca36@MCA lab111108]$ ./a.out pipe.c6



9) WRITE A C PROGRAM THAT ILLUSTRATES THE TWO WAY COMMUNICATION WITH UNIDIRECTIONAL PIPLE.Aim: To create two-way communication with unidirectional piple.

Program:

#include<stdlib.h>#include<stdio.h>#include<unistd.h>void do_child(int data_pipe[]){ int c; int rc; close(data_pipe[1]); while((rc=read(data_pipe[0],&c,1))>0) putchar(c); exit(0);}void do_parent(int data_pipe[]){ int c; int rc; close(data_pipe[0]); while((c=getchar())>0) { rc=write(data_pipe[1],&c,1); if(rc==-1) { printf("parent:write"); close(data_pipe[1]); exit(1); } } close(data_pipe[1]); exit(0);}int main(int argc, char *argv[]){



int data_pipe[2]; int pid; int rc; rc=pipe(data_pipe);

if(rc==-1) { printf("pipe"); exit(1); }

pid=fork(); switch (pid) { case -1: printf("fork"); exit(1); case 0: do_child(data_pipe); default: do_parent(data_pipe); } return 0;}

output:[mca36@MCA lab111108]$ ./a.out twopipe.cthis is unix labthis is unix lab^Z[1]+ Stopped ./a.out twopipe.c



10) WRITE A C PROGRAM THAT ILLUSTRATES THE TWO-WAY COMMUNICATION WITH BIDIRECTIONAL PIPE.Aim: To create two way communication with bidirectional pipe.Program:

#include<stdlib.h>#include<stdio.h>#include<unistd.h>#include<ctype.h>int main(int argc,char *argv[]){ int user_to_translator[2]; int translator_to_user[2];int pid;int rc;rc=pipe(user_to_translator);if(rc==-1){ printf("main:pipe user_to_translator"); exit(1);}rc=pipe(translator_to_user);if(rc==-1){ printf("main:pipe translator_to_user"); exit(1);}pid=fork();switch(pid){ case -1: perror("main:fork"); exit(1); case 0: translator(user_to_translator,translator_to_user); default: user_handler(translator_to_user,user_to_translator);}return 0;



}void user_handler(int input_pipe[],int output_pipe[]){ int c,rc;char ch; close(input_pipe[1]); close(output_pipe[0]);

while((c=getchar())>0){ ch=(char)c;rc=write(output_pipe[1],&ch,1);if(rc==-1) { printf("user hadler:write"); close(input_pipe[0]); close(output_pipe[1]); exit(1); } rc=read(input_pipe[0],&ch,1); c=(int)ch;if(rc<=0) { printf("user hadler:read"); close(input_pipe[0]); close(output_pipe[1]); exit(1); } putchar(c);}close(input_pipe[0]);close(output_pipe[1]);exit(0);}void translator(int input_pipe[],int output_pipe[]){ int c;char ch;int rc;close(input_pipe[1]);close(output_pipe[0]);while(read(input_pipe[0],&ch,1)>0){c=ch;if(isascii(c)&&isupper(c))c=tolower(c);ch=c;



rc=write(output_pipe[1],&ch,1);if(rc==-1){ printf("translator:write");close(input_pipe[0]); close(output_pipe[1]);exit(1);}

}

close(input_pipe[0]);close(output_pipe[1]);exit(0);}

output:[mca36@MCA lab121108]$ ./a.out bipipe.cTHIS IS UNIX LABthis is unix lab^Z[2]+ Stopped ./a.out bipipe.c.



11) WRITE A C PROGRAM THAT ILLUSTRATES THE CREATION OF CHILD PROCESS USING FORK SYSTEM CALL.Aim: To write a c program that illustrates the creation of child process using fork system call

Program :

#include<sys/types.h>#include"ourhdr.h"#include<stdlib.h>#include<stdio.h>#include<unistd.h>int glob=6;char buf[]="a write to stdout\n";int main(void){int var;pid_t pid;var=88;if(write(STDOUT_FILENO,buf,sizeof(buf)-1)!=sizeof(buf)-1) printf("write error");if((pid=fork())<0){ printf("fork error"); printf("before fork");}else if(pid==0){glob++;var++;}else sleep(2); printf("pid=%d,glob=%d,var=%d\n",getpid(),glob,var);}

output:[mca36@MCA lab121108]$ ./a.out fork1.ca write to stdout



pid=6981,glob=7,var=89pid=6980,glob=6,var=88

12) WRITE A C PROGRAM THAT DISPLAYS THE REAL TIME OF A DAY EVERY 60 SECOND

Aim :To . Write a c program that displays the real time of a day every 60 second

Program :#include<stdio.h>#include<time.h>int main(){int i=1; while(i<=10) { time_t now; time(&now); printf("current time is:%s",ctime(&now)); sleep(60); i++; }return 0;}

output:[mca36@MCA lab121108]$ ./a.out time.ccurrent time is:Tue Nov 25 11:30:05 2008



13) WRITE A C PROGRAM THAT ILLUSTRATES FILE LOCKING USING SEMAPHORES.

Aim : To write a c program that illustrates file locking using semaphores.

Program:

/* Initialization of a semaphore */#include<sys/types.h>#include<sys/ipc.h>#include<sys/sem.h>#include<stdio.h>#define KEY (1492)void main(){ int id; union semun { int val; struct semid *buf; ushort *array; }argument; argument.val=0; id=semget(KEY,1,0666|IPC_CREAT); if(id<0) { fprintf(stderr,"unable to obtain semaphore\n"); exit(0); } if(semctl(id,0,SETVAL,argument)<0) { fprintf(stderr,"cant set semaphore value \n"); } else { fprintf(stderr,"semaphore %d initialised\n",KEY); }



}

output:[mca36@MCA lab181108]$ ./filesemaphore 1492 initialised

b) /* semaphore using v operations*/

#include<stdio.h>#include<sys/types.h>#include<sys/ipc.h>#include<sys/sem.h>#define KEY (1492)void main(){ int id; struct sembuf operations[1]; int retval; id=semget(KEY,1,0666); if(id<0) { fprintf(stderr,"program sem.c cannot find semaphore exiting \n"); exit(0); } printf("program sem.c about to do a v-operation \n"); operations[0].sem_num=0; operations[0].sem_op=1; operations[0].sem_flg=0; retval=semop(id,operations,1); if(retval==0) { printf("successful v-operations by program sem.c \n"); } else { printf("semd:v-operation did not succeed \n"); perror("reason"); }}

output:[mca36@MCA lab181108]$ ./file1program sem.c about to do a v-operationsuccessful v-operations by program sem.c



C) /* semaphore using p operations*/

#include<stdio.h>#include<sys/types.h>#include<sys/ipc.h>#include<sys/sem.h>#define KEY (1492)void main(){ int id; struct sembuf operations[1]; int retval; id=semget(KEY,1,0666); if(id<0) { fprintf(stderr,"program sem1.c cannot find semaphore exiting \n"); exit(0); } printf("program sem1.c about to do a p-operation \n"); printf("process id is %d \n",getpid()); operations[0].sem_num=0; operations[0].sem_op=-1; operations[0].sem_flg=0; retval=semop(id,operations,1); if(retval==0) { printf("successful p-operations by program sem1.c \n"); printf("process id is %d \n",getpid()); } else { printf("semd:p-operation did not succeed \n"); perror("reason"); }}

output:[mca36@MCA lab181108]$ ./files



program sem1.c about to do a p-operationprocess id is 7519successful p-operations by program sem1.cprocess id is 7519

14) WRITE A C PROGRAM TO DEVELOP SIMPLE CLIENT AND SERVER APPLICATION USING SOCKET (SYSTEM CALLS) Aim:

To . write a c program to develop simple client and server application using socket (system calls)

Program:

/* server */#include<stdio.h>#include<stdlib.h>#include<errno.h>#include<string.h>#include<sys/types.h>#include<sys/socket.h>#include<sys/un.h>#define SOCK_PATH "echo_socket"int main(void){int s,t,len;struct sockaddr_un remote;char str[100];if((s=socket(AF_UNIX,SOCK_STREAM,0))==-1){printf("socket");exit(1);}printf("trying to connect..\n");remote.sun_family=AF_UNIX;strcpy(remote.sun_path,SOCK_PATH);len=strlen(remote.sun_path)+sizeof(remote.sun_family);if(connect(s,(struct sockaddr *)&remote,len)==-1){printf("connect eror");exit(1);}printf("connected.\n");



while(printf(">"),fgets(str,100,stdin),!feof(stdin)){if(send(s,str,strlen(str),0)==-1){printf("send error");exit(1);}

if((t=recv(s,str,100,0))>0){

//str[1]='\0';

printf("echo>%s",str);}else{if(t<0)printf("recv error");elseprintf("server closed connection\n");exit(1);}}close(s);return 0;}

/* client */

#include<stdio.h>#include<stdlib.h>#include<errno.h>#include<string.h>#include<sys/types.h>#include<sys/socket.h>#include<sys/un.h>#define SOCK_PATH "echo_socket"int main(void){int s,s2,t,len;struct sockaddr_un local,remote;char str[100];if((s=socket(AF_UNIX,SOCK_STREAM,0))==-1)



{printf("socket");exit(1);}local.sun_family=AF_UNIX;strcpy(local.sun_path,SOCK_PATH);unlink(local.sun_path);len=strlen(local.sun_path)+sizeof(local.sun_family);

if(bind(s,(struct sockaddr*)&local,len)==-1){printf("bind error");exit(1);

}if(listen(s,5)==-1){

printf("listen");exit(1);}for(;;){int done,n;printf("waiting for a connection...\n");t=sizeof(remote);if((s2=accept(s,(struct sockaddr*)&remote,&t))==-1){printf("accept error");exit(1);}printf("connected.\n");done=0;do{n=recv(s2,str,100,0);if(n<=0){if(n<0)printf("recv error");done=1;}if(!done)if(send(s2,str,n,0)<0){printf("send error");



done=1;}}while(!done);close(s2);}return 0;}

Out put: $ cc –o echores echoc.c $ cc –o rep echos.c$./ echores $ ./rep Waiting for a connectionTrying to connect…. connectedConnected .

> this is a program echo > this is a program > illustratingecho > illustrating>usage of echo > usage of >Socketsecho > Sockets



15). Write a c program that illustrates inter process communication using shared memoryAim: To Write a c program that illustrates inter process communication using shared memory

Program,:

#include<stdio.h>#include<stdlib.h>#include<string.h>#include<sys/ipc.h>#include<sys/shm.h>#define SHM_SIZE 1024int main(int argc,char *argv[]){ key_t key; int shmid; char *data; int mode; if(argc>2) { fprintf(stderr,"usage:shmdemo(data_to_write)\n"); exit(1); } if((key=ftok("share.c",'r'))==-1) { printf("ftok"); exit(1); } if((shmid=shmget(key,SHM_SIZE,0644)IPC_CREAT)==-1) { printf("shmget"); exit(1); } data=shmat(shmid,(void *),0,0); if(data==(char)*(-1)) { printf("shmat");



exit(1); } if(argc==2) { printf("writing to segment:\%s\n",argv[1]); strcpy(dat,argv[1],SHM_SIZE); } else

printf("segment contains:\%s\n",data); if(shmdt(data)==-1) { perror("shmdt"); exit(1); } return 0;}

Out put :./a.out unixWriting to segment : unix



16) WRITE A C PROGRAM THAT ILLUSTRATES THE FOLLOWING A) CREATING A MESSAGE QUEUE B) WRITING TO A MESSAGE QUEUE C) READING FROM MESSAGE QUEUE

Aim: To . Write a c program that illustrates the following a) Creating a message queue b) Writing to a message queue c ) Reading from message queueProgram :

#include<stdio.h>#include<stdlib.h>#include<errno.h>#include<sys/types.h>#include<sys/msg.h>struct msg_msgbuf{ long mtype; char mtext[200];};int main(void){ struct msg_msgbuf buf; int msgid; key_t key; if((key=ftok("msg1.c",'b'))==-1) { printf("ftok"); exit(1); } if((msgid=msgget(key,0644|IPC_CREAT))==-1) { printf("msgget"); exit(1); } printf("enter lines of text and to quit:\n");



buf.mtype=1; while(gets(buf.mtext),!feof(stdin)) { if(msgsnd(msgid,(struct msgbuf*)&buf,sizeof(buf),0)==-1) printf("msgsnd"); } if(msgctl(msgid,IPC_RMID,NULL)==-1) { printf("msgctl");

exit(1); }

return 0;}output:[mca36@MCA lab181108]$ ./mmenter lines of text and to quit:this is unix labprogramming^Z[3]+ Stopped ./mmb)#include<stdio.h>#include<stdlib.h>#include<errno.h>#include<sys/types.h>#include<sys/ipc.h>#include<sys/msg.h>struct msg_msgbuf{ long mtype; char mtext[200];};int main(void){ struct msg_msgbuf buf; int msgid; key_t key; if((key=ftok("msg1.c",'b'))==-1) { printf("ftok"); exit(1); } if((msgid=msgget(key,0644))==-1) { perror("msgget"); exit(1);



} printf("spock:ready to receive messages,obtain \n"); for(;;) {

if(msgrcv(msgid,(struct msgbuf *)&buf,sizeof(buf),0,0)==-1) { perror("msgrcv"); exit(1);

} printf("spock:\"%s\"\n",buf.mtext);} return 0;}

output:[mca36@MCA lab181108]$ ./mmmspock:ready to receive messages,obtainspock:"this is unix lab"spock:”programming”

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