np lab record

7/29/2019 NP Lab Record

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1. Write a shell script that accepts a file name, starting and ending linenumbers as arguments and displays all the lines between the given line

numbers.

echo 'enter a filename'

read fname

echo 'enter starting line number'

read stecho 'enter ending line number'

read eno

echo 'the lines between '$st 'and' $eno 'from' $fname

sed -n "$st,$eno p" $fname

2. Write a shell script that deletes all lines containing a specified word inone or more files supplied as arguments to it.

if [ $# -eq 0 ]

thenecho "no arguments"

else

echo "enter a deleting word or char"

read y

for i in $*

do

grep -v "$y" "$i" > temp

if [ $? -ne 0 ]

thenecho "pattern not found"

else

cp temp $i

rm temp

fi

done

fi

3. Write a shell script that displays a list of all the files in the currentdirectory to which the user has read, write and execute permissions.pwd

for i in `ls`

do

if [ -r $i -a -w $i -a -x $i ]

then

echo "$i has all permissions"

ls -l $i

fidone


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4. Write a shell script that receives any number of filenames asarguments checks if every argument supplied is a file or a directory and

reports accordingly. Whenever the argument is a file, the number of lines on

it is also reported.

for fname in $*

do

if [ -f $fname ]then

echo $fname 'is a file'

echo 'no.of lines in' $fname ':'

wc -l $fname

elif [ -d $fname ]

then

echo $fname 'is a directory'

else

echo 'Does not exist'fi

done

5. Write a shell script that accepts a list of file names as its arguments,counts and reportsthe occurrence of each word that is present in the first

argument file on other argument files.

if [ $# -eq 0 ]

then

echo "no arguments"

elsetr " " "\n" < $1 > temp

shift

for i in $*

do

tr " " "\n" < $i > temp1

y=`wc -l < temp`

j=1

while [ $j -le $y ]

do

x=`head -n $j temp | tail -1`

c=`grep -c "$x" temp1`

echo $x $c

j=`expr $j + 1`

done

done

fi

6. Write a shell script to list all of the directory files in a directory.echo 'enter a directory name'

read name

echo 'The list of files in the directory' $name 'are'

ls -l $dname>file

grep '^d' file


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7. Write a shell script to find factorial of a given integer.echo 'enter a number'

read n

i=1

fact=1

while [ $i -le $n ]

dofact=`expr $fact \* $i`

i=`expr $i + 1`

done

echo 'The factorial of' $n 'is' $fact

8. Write an awk script to count the number of lines in a file that do notcontain vowels.

echo "enter a file name"

readfnawk '$0 !~/[aeiou]/ {c=c+1}

END {print("the no. of lines that do not contain vowels:",c)}' $fn

9. Write an awk script to find the number of characters, words and linesin a file.

echo "enter a file name"

readfn

awk '{ w=w+NF

c=c+length($0)}

END{ print("no. oflines:",NR)

print("no. ofwords:",w)

print("no. ofcharacters:",c)

}' $fn

10. Write a C program that makes a copy of a file using standard I/O andsystem calls.

#include

#include

#define MAX_SIZE 1000

main() {

int fd1,fd2,r1,w1;

char buffer[MAX_SIZE];

charsourceName[100],destName[100];

printf("enter the source file\n");

scanf("%s",sourceName);

printf("enter a new file name");

scanf("%s",destName);

fd1=open(sourceName,O_RDONLY);

r1=read(fd1,buffer,MAX_SIZE);

fd2=open(destName,O_CREAT|O_RDWR,0600);

w1=write(fd2,buffer,r1);}


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11. Implement in C the following Unix commands using System callsa) . cat#include

#include

#include

#include

#include

int main(int argc,char *argv[])

{

int fd1,fd2;

intn,count=0;

fd1=open(argv[1],O_RDONLY);

fd2=creat(argv[2],S_IWUSR);

rename(argv[1],argv[2]);

unlink(argv[1]);

return(0); }

b) mv#include

#include

#include

#include

#include

int main(int argc,char *argv[])

{

int fd1,fd2;

intn,count=0;fd1=open(argv[1],O_RDONLY);

fd2=creat(argv[2],S_IWUSR);

rename(argv[1],argv[2]);

unlink(argv[1]);

return(0);

}

12. Write a C program to emulate the Unixlsl command.#include #include

#include

main()

{

pid_tchildpid;

childpid=fork();

switch(childpid)

{

case -1:fprintf(stderr,"ERROR: %s \n", sys_errlist[errno]);

exit(1);

break;


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case 0:

execl("/bin/ls","ls","-l",NULL);

perror("child fAiled to exec1 ls");

printf("child code goes here");

break;

default:

perror("parent failed to wait due to signal or error");

printf("parent code goed here");

break;

}

}

13. Write a C program to create a child process and allow the parent todisplay parent andthe child to display child on the screen.

#include

main()

{

int a;

a=fork();

if(a>0)

printf("parent \n");

else

printf("child \n");

}

14. Write a C program to create a Zombie process.#includemain()

{

intpid;

pid=fork();

if(0==pid)

{

printf("child process %d \n",getpid());

}

else{

wait(0);

sleep(30);

printf("parent process \n");

}

}

15. Write a C program that illustrates how an orphan is created.

#includemain()

{

intpid;


6/156

pid=fork();

if(0==pid)

{

printf("%d\n",getpid());

sleep(5);

printf("%d\n",getpid());

}

else

{

printf("bye from parent\n");

}

}

16. Write a C program that illustrates how to execute two commandsconcurrently with a command pipe. Ex:- lsl | sort

#include

main()

{

int p[2],pid;

pipe(p);

pid=fork();

if(0==pid)

{

close(p[0]);

dup2(p[1],1);execl("/bin/ls","ls",(char *)0);

perror("ls");

}

else

{

close(p[1]);

dup2(p[0],0);

execl("/usr/bin/wc","wc",(char *)0);

perror("wc");}

}

17. Write a C program in which a parent writes a message to a pipe and thechild reads the message.

#include

main()

{

int p[2],pid;char *buf;

buf=(char *) malloc(10);

pipe(p);


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pid=fork();

if(pid>0)

{

printf("parent is writing on pipe");

write(p[1],"hello",5);

}

else

{

read(p[0],buf,5);

printf("child is reading %s \n",buf);

}

close(p[0]);

close(p[1]);

}

18. Write a C program (sender.c) to create a message queue with read andwrite permissions to write 3messages to it with different priority numbers.

#include

#include

#include

#include

structmsgbuf{

longmtype;

charmtext[40]; };

main() {intmsqid,len,ret;

structmsgbufmsgsend={0,"\0"};

msqid=msgget((key_t)7,IPC_CREAT|0666);

if(-1==msqid) {

perror("msgget:");

exit(1); }

printf("enter msgtype:\n");

scanf("%d",&msgsend.mtype);

printf("enter msgtext:\n");scanf("%s",msgsend.mtext);

len=strlen(msgsend.mtext);

ret=msgsnd(msqid,&msgsend,len,0);

if(-1==ret)

{

perror("msgsnd:");

exit(1);

}

elseprintf("msgsent:\n");

}


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19. Write a C program (receiver.c) that receives the messages and displaysthem.

#include

#include

#include

#include

structmsgbuf{

longmtype;

charmtext[40];

};

main()

{

intmsqid,len,type,ret;

structmsgbufmsgread={0,"\0"};

msqid=msgget((key_t)7,IPC_CREAT|0666);

if(-1==msqid)

{

perror("msgget:");

exit(1);

}

printf("enter the msg type:\n");

scanf("%d",&type);

len=sizeof(msgread.mtext);

ret=msgrcv(msqid,&msgread,len,type,0);

printf("ret=%d\n",ret);

if(-1==ret){

perror("msgrcv:");

exit(1);

}

else

printf("message type=%d message text=%s\n",msgread.mtype,msgread.mtext);

}

20. Write a C program that illustrates suspending and resuming processesusing signals.

#include

#include

void fun(int k)

{

printf("signal is caught %d\n",k);

}

void bun(int p){

printf("i am in bun %d\n",p);

}


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main()

{

signal(SIGINT,SIG_IGN);

sleep(5);

signal(SIGINT,fun);

sleep(5);

signal(SIGINT,bun);

sleep(5);

signal(SIGINT,SIG_DFL);

for( ; ; );

}

21. Write a C program that implements a producer-consumer system withtwo processes (using Semaphores).

#include

#include

#include

#include

#include

voidabc()

{

printf("bye bye from child\n");

exit(0);

}

void xyz()

{printf("bye bye from parent\n");

exit(0);

}

main()

{

intsemid;

intpid;

structsembuf sop;

semid=semget((key_t)29,1,IPC_CREAT|0666);if(-1==semid)

{

perror("semget:");

exit(1);

}

semctl(semid,0,SETVAL,6);

printf("semid=%d\n",semid);

pid=fork();

if(0==pid){

sop.sem_num=0;

sop.sem_op=-1;


10/1510

sop.sem_flg=0;

signal(SIGALRM,abc);

alarm(6);

while(1)

{

semop(semid,&sop,1);

printf("child%d\n",semctl(semid,0,GETVAL,0));

sleep(1);

}

}

else

{

sleep(7);

sop.sem_num=0;

sop.sem_op=1;

sop.sem_flg=0;

signal(SIGALRM,xyz);

alarm(6);

while(1)

{

semop(semid,&sop,1);

printf("parent%d\n",semctl(semid,0,GETVAL,0));

sleep(1);

}

}

}

22. Write client and server programs (using C) for interaction betweenserver and client processes using Unix Domain sockets.

a) SERVER :-#include

#include

#include #include

#define NSTRS3 /* no. of strings */

#define ADDRESS"mysocket"/* addr to connect */

/*Strings we send to the client. */

char *strs[NSTRS] = {

"This is the first string from the server.\n",

"This is the second string from the server.\n","This is the third string from the server.\n"

};


11/1511

main() {

char c;

FILE *fp;

intfromlen;

register int i, s, ns, len;

structsockaddr_unsaun, fsaun;

/*Get a socket to work with. This socket willbe in the UNIX domain, and will

be astream socket. */

if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {

perror("server: socket");

exit(1);

}

/*Create the address we will be binding to. */

saun.sun_family = AF_UNIX;

strcpy(saun.sun_path, ADDRESS);

/*Try to bind the address to the socket. Weunlink the name first so that the bind

won'tfail.

The third argument indicates the "length" ofthe structure, not just the length of

thesocket name.*/

unlink(ADDRESS);

len = sizeof(saun.sun_family) + strlen(saun.sun_path);

if (bind(s, &saun, len) < 0) {perror("server: bind");

exit(1);

}

/*Listen on the socket.*/

if (listen(s, 5) < 0) {

perror("server: listen");

exit(1);

}

/*Accept connections. When we accept one, nswill be connected to the client.

fsaun willcontain the address of the client. */

if ((ns = accept(s, &fsaun, &fromlen)) < 0) {

perror("server: accept");

exit(1);

}

/*We'll use stdio for reading the socket. */fp = fdopen(ns, "r");

/*First we send some strings to the client. */


12/1512

for (i = 0; i < NSTRS; i++)

send(ns, strs[i], strlen(strs[i]), 0);

/*Then we read some strings from the client andprint them out. */

for (i = 0; i < NSTRS; i++) {

while ((c = fgetc(fp)) != EOF) {

putchar(c);

if (c == '\n')

break;

}

}

/*We can simply use close() to terminate theconnection, since we're done with

both sides. */

close(s);

exit(0);

}

b) CLIENT:-#include

#include

#include

#include

#define NSTRS 3 /* no. of strings */

#define ADDRESS "mysocket" /* addr to connect */

/*Strings we send to the server.*/

char *strs[NSTRS] = {

"This is the first string from the client.\n",

"This is the second string from the client.\n",

"This is the third string from the client.\n"};

main()

{

char c;

FILE *fp;

register int i, s, len;

structsockaddr_unsaun;

/*Get a socket to work with. This socket willbe in the UNIX domain, and will be

astream socket. */


13/1513

if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {

perror("client: socket");

exit(1);

}

/*Create the address we will be connecting to. */

saun.sun_family = AF_UNIX;

strcpy(saun.sun_path, ADDRESS);

/*Try to connect to the address. For this tosucceed, the server must already

have boundthis address, and must have issued a listen()request.

The third argument indicates the "length" ofthe structure, not just the length of

thesocket name. */

len = sizeof(saun.sun_family) + strlen(saun.sun_path);

if (connect(s, &saun, len) < 0) {

perror("client: connect");

exit(1);

}

/*We'll use stdio for readingthe socket. */

fp = fdopen(s, "r");

/*First we read some strings from the serverand print them out. */

for (i = 0; i < NSTRS; i++) {

while ((c = fgetc(fp)) != EOF) {putchar(c);

if (c == '\n')

break;

}

}

/*Now we send some strings to the server. */

for (i = 0; i < NSTRS; i++)send(s, strs[i], strlen(strs[i]), 0);

/*We can simply use close() to terminate theconnection, since we're done with

both sides. */

close(s);

exit(0);

}

c) Write client and server programs(using c) for interaction between serverand client processes using Internet Domain sockets.


14/1514

23. Write a C program that illustrates two processes communicating viashared memory.

a)#include

#include

#include

#include

#define SHMSZ 27

main()

{

char c;

intshmid;

key_t key;

char *shm, *s;

key = 5678;

if ((shmid = shmget(key, SHMSZ, IPC_CREAT | 0666)) < 0) {

perror("shmget");

exit(1);

}

printf("shmid=%d\n",shmid);

/* Now we attach the segment to our data space.*/

if ((shm = shmat(shmid, NULL, 0)) == (char *) -1) {perror("shmat");

exit(1);

}

/*Now put some things into the memory for the other process to read. */

s = shm;

for (c = 'a'; c


15/15

b)#include

#include

#include

#include

#define SHMSZ 27

main()

{

intshmid;

key_t key;

char *shm, *s;

/*We need to get the segment named"5678", created by the server.*/

key = 5678;

/*Locate the segment. */

if ((shmid = shmget(key, SHMSZ, 0666)) < 0) {

perror("shmget");

exit(1);

}

/*Now we attach the segment to our data space. */

if ((shm = shmat(shmid, NULL, 0)) == (char *) -1) {

perror("shmat");

exit(1);}

/*Now read what the server put in the memory. */

for (s = shm; *s != NULL; s++)

putchar(*s);

putchar('\n');

/*Finally, change the first character of the segment to '*', indicating we have read

the segment. */

*shm = '*';

exit(0);}

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