..

2. Simple shell script for basic arithmetic and logical calculations.

#!/bin/sh

a=2

b=4

c=3

val=`expr $a + $b`

echo "Sum = $val"

val=`expr $a - $b`

echo "Difference= $val"

val=`expr $a \* $b`

echo "Product = $val"

val=`expr $b / $a`

echo "quotient = $val"

val=`expr $a % $b`

echo "Modulus = $val"

if [ $a == $b ]

then

echo “a is equal to b”

else

echo “a is not equal to b”

if [ $a != $b ]

then

echo “a is equal to b”

else

echo “a is not equal to b”

if [ $a -lt 10 -o $b -gt 20 ]

then

echo “true”

else

echo “false”

if [ $a -lt 10 -a $b -gt 20 ]

then

echo “True”

else

echo “False”

[LabExam@ISELAB1 ~]$chmod a+x pr2.sh /*To execute your shell program, use chmod a+x program name(For changing mode), a+x means giving execute permission to all three category of people(user,group,others).*/

[LabExam@ISELAB1 ~]$sh pr2.sh /*To run the program use any of the methods: sh program name or ./ program name*/

Sum = 8

Difference = -2

Product =8

Quotient =2

Modulus =2

a is not equal to b

True

False

3. Shell scripts to check various attributes of files and directories.

#!/bin/sh

file="filename.sh"

if [ -r $file ]

then

echo "File has read permission"

else

echo "File does not have read permission"

if [ -w $file ]

then

echo "File has write permission"

else

echo "File does not have write permission"

if [ -x $file ]

then

echo "File has execute permission"

else

echo "File does not have execute permission"

if [ -f $file ]

then

echo "File is an ordinary file"

else echo "This is a special file"

if [ -d $file ]

then

echo "File is a directory"

else

echo "File is not a directory"

if [ -s $file ]

then

echo "File size is zero"

else

echo "File size is greater than zero"

if [ -e $file ]

then

echo "File exists"

else

echo "File does not exist"

if [ -b $file ]

then

echo "File is a block file "

else

echo "File is not a block file"

if [ -c $file ]

then

echo "File is a character file "

else

echo "File is not a character file"

output: [LabExam@ISELAB1 ~]$ sh pr3.sh

[LabExam@ISELAB1 ~]$chmod a+x pr3.sh

[LabExam@ISELAB1 ~]$sh pr3.sh

File has read permission

File has write permission

File has execute permission

File is an ordinary file

File size is greater than zero

File exists

File is not a character file is not a block file

4. Shell scripts to check and list attributes of processes.

!/bin/sh

echo "ps : process status"

ps -f

echo "ps -f : full listing"

ps -l

echo "ps -l : along listing showing memory related information"

ps -u

echo "ps -u : process of user only"

ps -e

echo "ps -e : all process including user and system process"

ps -a

echo "ps -a : process of all user including processes not listed with terminal"

ps -t

echo "ps -t : processes running on terminal -l along listing showing memory related information"

output:

[LabExam@ISELAB1 ~]$ sh pr4.sh

[LabExam@ISELAB1 ~]$chmod a+x pr4.sh

[LabExam@ISELAB1 ~]$sh pr4.sh

PID TTY TIME CMD

2053 pts/0 00:00:00 bash

2422 pts/0 00:00:00 listing.sh

2423 pts/0 00:00:00 ps

ps = process status

UID PID PPID C STIME TTY TIME CMD

admin 2053 2043 0 10:46 pts/0 00:00:00 bash

admin 2422 2053 0 11:03 pts/0 00:00:00 /bin/sh ./listing.sh

admin 2424 2422 0 11:03 pts/0 00:00:00 ps -f

ps -f=full listing

F S UID PID PPID C PRI NI ADDR SZ WCHAN TTY TIME CMD

0 S 1000 2053 2043 0 80 0 - 2306 wait pts/0 00:00:00 bash

0 S 1000 2422 2053 0 80 0 - 2045 wait pts/0 00:00:00 listing.sh

0 R 1000 2425 2422 0 80 0 - 2868 - pts/0 00:00:00 ps

ps -l=along listing showing memory related information

USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND

admin 1403 0.0 0.2 54036 9432 tty2 Ssl+ 10:46 0:00 /usr/libexec/gd

admin 1408 0.0 0.3 84184 12864 tty2 Sl+ 10:46 0:00 /usr/libexec/gn

admin 1510 3.3 3.8 1117800 135452 tty2 Sl+ 10:46 0:34 /usr/bin/gnome-

admin 1538 0.0 1.2 155672 44816 tty2 Sl+ 10:46 0:00 /usr/bin/Xwayla

admin 1571 0.3 0.2 52168 7748 tty2 Sl 10:46 0:03 ibus-daemon --x

ps -u=process of user only

PID TTY TIME CMD

1 ? 00:00:01 systemd

2 ? 00:00:00 kthreadd

3 ? 00:00:00 rcu_gp

4 ? 00:00:00 rcu_par_gp

6 ? 00:00:00 kworker/0:0H-kb

ps -e=all process including user and system process

PID TTY TIME CMD

868 tty1 00:00:00 gnome-session-b

907 tty1 00:00:03 gnome-shell

1136 tty1 00:00:00 Xwayland

1163 tty1 00:00:00 ibus-daemon

1166 tty1 00:00:00 ibus-dconf

ps -a=process of all user including processes not listed with terminal

PID TTY STAT TIME COMMAND

2053 pts/0 Ss 0:00 bash

2422 pts/0 S+ 0:00 /bin/sh ./listing.sh

2429 pts/0 R+ 0:00 ps -t

ps -t=processes running on terminal -l along listing showing memoryb related information

5. Write awk script that uses all of its features.

#!/bin/awk -f

BEGIN {print “START”}

{print $1, “\t”, $3}

END {print “DONE”}

output:

[LabExam@ISELAB1 ~]$ awk -f pr5.awk a.txt

And am

You can

Me you

LabExam@ISELAB1 ~]$ cat a.txt

And is am I was

You they can take

Me as you print

6. Write a shell script to display list of users currently logged in.

#!/bin/sh

echo “User logged in:”

users

echo “Current logged in date and time :”

date

echo “Currently logged in users:”

who

echo “Currently logged in username:”

whoami

output:

[LabExam@ISELAB1 ~]$ sh pr6.sh

[LabExam@ISELAB1 ~]$chmod a+x pr6.sh

[LabExam@ISELAB1 ~]$sh pr6.sh

User logged in:

UNIX LAB UNIX LAB

Current logged in date and time:

Sat sep 29 12:25:30 IST 2018-11-22

Currently logged in users:

UNIXLAB TTY1 2018-09-29 11.08 (:0)

UNIXLAB pts/0 2018-09-29 12.03 (:0.0)

UNIXLAB pts/1 2018-09-29 12.28 (:0.0)

Currently logged in username:

UNIXLAB

PART B

1. Write a C/C++ program to implement the cat command using general file API’s.

#include<sys/types.h>

#include<sys/stat.h>

#include<stdio.h>

#include<fcntl.h>

main( int argc,char *argv[3] )

{

int fd,i;

char buf[2];

fd=open(argv[1],O_RDONLY,0777);

if(fd==-argc)

{

printf("file open error");

}

else

{

while((i=read(fd,buf,1))>0)

{

printf("%c",buf[0]);

}

close(fd);

}

Output: [UNIXLAB@localhost ~]$ gcc -0 p.out prgm1.c

UNIXLAB@localhost ~]$cat >h.txt /*creating a text file*/

hello

UNIXLAB@localhost ~]$./p.out h.txt /*appending text file to display contents on the terminal without using cat command*/

hello

2. Write a C/C++ program to implement the cp (copy) command using general file API’s.

#include <stdio.h>

#include <stdlib.h

#include <fcntl.h>

#include <errno.h>

#define BUFF_SIZE 1024

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

{

int srcFD,destFD,nbread,nbwrite;

char *buff[BUFF_SIZE];

/*Check if both src & dest files are received*/

if(argc != 3)

{

printf("\nUsage: cpcmd source_file destination_file\n");

exit(EXIT_FAILURE);

}

/*Open source file*/

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

if(srcFD == -1)

{

printf("\nError opening file %s errno = %d\n",argv[1],errno);

exit(EXIT_FAILURE);

}

/*Open destination file with respective flags & modes

O_CREAT & O_TRUNC is to truncate existing file or create a new file

S_IXXXX are file permissions for the user,groups & others*/

destFD = open(argv[2],O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR |

S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);

if(destFD == -1)

{

printf("\nError opening file %s errno = %d\n",argv[2],errno);

exit(EXIT_FAILURE);

}

/*Start data transfer from src file to dest file till it reaches EOF*/

while((nbread = read(srcFD,buff,BUFF_SIZE)) > 0)

{

if(write(destFD,buff,nbread) != nbread)

printf("\nError in writing data to %s\n",argv[2]);

}

if(nbread == -1)

printf("\nError in reading data from %s\n",argv[1]);

if(close(srcFD) == -1)

printf("\nError in closing file %s\n",argv[1]);

if(close(destFD) == -1)

printf("\nError in closing file %s\n",argv[2]);

exit(EXIT_SUCCESS);

}

Output: Output: gcc prgm2.c

[UNIXLAB@localhost ~]$ ./a.out q.txt j.txt

UNIXLAB@localhost ~]$cat q.txt

hello

UNIXLAB@localhost ~]$cat j.txt

hello

3. Write a C/C++ program to implement the ln/rename command using general file API’s.

#include <stdio.h>

#include<unistd.h>

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

{

if(argc!=3)

{

printf(“usage: %s <src_file><dest_file>\n”,argv[0]);

Return 0;

}

if(link(argv[1],argv[2])==-1)

{

printf(“link error\n”);

return 1;

}

printf(“files linked\n”);

printf(“Inode number of linked files\n”);

char str[100];

sprint(str,”ls –i %s %s \n”,argv[1],argv[2]);

system(str);

return 0;

}

Output: gcc prgm1.c

[UNIXLAB@localhost ~]$ ./a.out j.txt q.txt

Files linked

Inode number of linked files

416529 j.txt 416529 q.txt

4. Write a C/C++ program to create a file called file1 in blocking read-write mode and show how you can use fcntl api to modify its access control flags to non-blocking read-write mode.

#include<stdio.h>

#include<sys/types.h>

#include<fcntl.h>

#include<stdlib.h>

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

{

int accmode,val;

if(argc!=2)

{

fprintf(stderr,"usage:%s <description>",argv[0]);

exit(1);

}

val=fcntl(atoi(argv[1]),F_GETFL,0); /* F_GETFL (void)

Return (as the function result) the file access mode and the

file status flags;*/

if(val<0)

{

perror("fcntl error for fd");

exit(1);

}

accmode=val & O_ACCMODE; /*This macro stands for a mask that can be bitwise-ANDed with the file status flag value to produce a value representing the file access mode. The mode will be O_RDONLY, O_WRONLY, or O_RDWR.*/

if(accmode==O_RDONLY)

printf("read only");

else if(accmode==O_WRONLY)

printf("Write only");

else if(accmode==O_RDWR)

printf("read write");

else

{

fprintf(stderr,"unknown access mode");

exit(1);

}

if(val & O_APPEND)

printf(",append");

if(val & O_NONBLOCK)

printf(",nonblocking");

if(val & O_SYNC)

printf(",synchronous write"); /*wait for writes to complete (data and attributes)*/

putchar('\n');

exit(0);

}

Output:

gcc p22.c

[UNIXLAB@localhost ~]$ ./a.out p22.c

Read-Write

5.Write a C/C++ program to duplicate the file descriptor of a file Foo to standard input file descriptor.

#include<stdlib.h>

#include<unistd.h>

#include<sys/types.h>

#include<sys/stat.h>

#include<fcntl.h>

#include<stdio.h>

int main(int argc,char **argv)

{

int fd,nfd;

if(argc<2){

printf("usage:%s pathname\n",argv);

exit(1);

}

if((fd=open(argv[1],O_WRONLY))<0)

{

perror("Problem in opening the file");

exit(1);

}

if((nfd=fcntl(fd,F_DUPFD,0))==-1)

{

perror("Problem in duplicating fd");

exit(1);

}

printf("Fd %d duplicated with %d\n",fd,nfd);

close(fd);

close(nfd);

}

Output: gcc prgm.c

[UNIXLAB@localhost ~]$ ./a.out ll.txt

Fd 3 duplicated with 4

gcc prgm.c

[UNIXLAB@localhost ~]$ ./a.out ll.txt

Fd 3 duplicated with 4

6.Write a C/C++ program to query and display the different attributes associated with a file.

#include<stdio.h>

#include<sys/types.h>

#include<sys/stat.h>

#include<time.h>

#include<stdlib.h>

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

{

struct stat sb;

if(argc!=2)

{

fprintf(stderr,"usage: %s <pathname>\n", argv[0]);

exit(EXIT_FAILURE);

}

if(stat(argv[1],&sb)==-1)

{

perror("stat");

exit(EXIT_FAILURE);

}

printf("file type: ");

switch(sb.st_mode & S_IFMT)

{

case S_IFBLK: printf("block device file\n");

break;

case S_IFCHR: printf("character device file\n");

break;

case S_IFDIR: printf("directory\n");

break;

case S_IFIFO: printf("FIFO/pipe\n");

break;

case S_IFLNK: printf("symlink\n");

break;

case S_IFREG: printf("regular file\n");

break;

case S_IFSOCK: printf("socket\n");

break;

default: printf("regular file\n");

break;

}

printf("Inode number: %ld\n", (long) sb.st_ino);

printf("Mode: %lo(octal)\n", (unsigned long) sb.st_mode);

printf("Blocks allocated: %lld\n", (long long) sb.st_blocks);

exit(EXIT_SUCCESS);

}

Output: gcc prgm.c

[UNIXLAB@localhost ~]$ ./a.out prgm.c

File type: regular

Inode number: 1067168

Mode: 100664(octal)

Blocks allocated: 8

struct stat {

dev_t st_dev; /* ID of device containing file */

ino_t st_ino; /* Inode number */

mode_t st_mode; /* File type and mode */

nlink_t st_nlink; /* Number of hard links */

uid_t st_uid; /* User ID of owner */

gid_t st_gid; /* Group ID of owner */

dev_t st_rdev; /* Device ID (if special file) */

off_t st_size; /* Total size, in bytes */

blksize_t st_blksize; /* Block size for filesystem I/O */

blkcnt_t st_blocks; /* Number of 512B blocks allocated */

time_t st_atime; /* Time of last access */

time_t st_mtime; /* Time of last modification */

time_t st_ctime; /* Time of last status change */

};

7.Write C/C++ program to read and display the last 10 character’s of the input file.

#include<stdio.h>

#include<stdlib.h>

int main()

{

FILE *fp;

char ch;

int num;

long length;

printf("Enter the value of num:");

scanf("%d",&num);

fp=fopen("file.txt","r");

if(fp==NULL)

{

puts("Cannot open this file");

exit(1);

}

fseek(fp,-1,SEEK_END);

length=ftell(fp);

fseek(fp,(length-num),SEEK_SET);

{

ch=fgetc(fp);

putchar(ch);

}while(ch!=EOF);

fclose(fp);

return(0);

}

Output

cat > l.txt

hello world hai beautiful girl

gcc p55.c

[UNIXLAB@localhost ~]$ ./a.out p55.c

Enter the value of num:4

Girl

8.Write a C/C++ program to demonstrate masking of read/write/execute permission of a specified input file for user group and others category.

#include<sys/types.h>

#include<sys/stat.h>

#include<stdio.h>

int main()

{

mode_t oldMask,newMask;

oldMask=umask((mode_t)0);

printf("\n Old mask = %on",(int)oldMask);

if(oldMask & S_IRGRP){

printf("\nChanging group read permission from Masked to unmasked.n");

oldMask=(oldMask ^ S_IRGRP);/* ^ Operator is binar XOR operator, copies the bit if it is set in one operand but not in both. Exclusive or is a logical operator that outputs true only when inputs differ*/

}

newMask=(oldMask|S_IWGRP|S_IXGRP);

umask(newMask);

printf("\nNew MAsk = %onn",(int)newMask);

printf("\nThe file mode creation mask now specifies:nn");

printf("\n Group read permission UNMASKEDn");

printf("\n Group write permission MASKEDn");

printf("\n Group execute permission MASKEDn");

oldMask=umask((mode_t)0);

printf("\n Old mask = %on",(int)oldMask);

if(oldMask & S_IRUSR){

printf("\nChanging user read permission from Masked to unmasked.n");

oldMask=(oldMask ^ S_IRUSR);

}

newMask=(oldMask|S_IWUSR|S_IXUSR);

umask(newMask);

printf("\nNew MAsk = %onn",(int)newMask);

printf("\nThe file mode creation mask now specifies:nn");

printf("\n User read permission UNMASKEDn");

printf("\n User write permission MASKEDn");

printf("\n User execute permission MASKEDn");

oldMask=umask((mode_t)0);

printf("\n Old mask = %on",(int)oldMask);

if(oldMask & S_IROTH){

printf("\nChanging Other read permission from Masked to unmasked.n");

oldMask=(oldMask ^ S_IROTH);

}

newMask=(oldMask|S_IWOTH|S_IXOTH);

umask(newMask);

printf("\nNew MAsk = %onn",(int)newMask);

printf("\nThe file mode creation mask now specifies:nn");

printf("\n Other read permission UNMASKEDn");

printf("\n Other write permission MASKEDn");

printf("\n Other execute permission MASKEDn");

}

Output:

gcc p77.c

[UNIXLAB@localhost ~]$ ./a.out p77.c

Old mask = 2n

New MAsk = 32nn

The file mode creation mask now specifies:nn

Group read permission UNMASKEDn

Group write permission MASKEDn

Group execute permission MASKEDn

Old mask = 32n

New MAsk = 332nn

The file mode creation mask now specifies:nn

User read permission UNMASKEDn

User write permission MASKEDn

User execute permission MASKEDn

Old mask = 332n

New MAsk = 333nn

The file mode creation mask now specifies:nn

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