Linux Search Pattern Question: Download Search Pattern PDF

Do you know what is the output of this program?

#include<stdio.h>
#include<stdlib.h>
#include<fcntl.h>

int main()
{
int fd;
char buff;
buff = (char )malloc(sizeof(char)*5);
fd = open("google.txt",O_RDWR|O_CREAT);
write(fd,"Linux",5);
read(fd,buff,5);
printf("%sn",buff);
}
a) it will print nothing
b) it will print the string "Linux"
c) segmentation fault
d) none of the mentioned

Answer:

a) it will print nothing
Explanation:
We have to use "lseek" system call if we want to read the file from the beginning just after writing into it.
Output:
[root@localhost google]# gcc -o san san.c
[root@localhost google]# ls
san san.c
[root@localhost google]# ./san
[root@localhost google]# ls
san san.c google.txt
[root@localhost google]# vim google.txt
[root@localhost google]#

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Tell me what is the output of this program? #include<stdio.h> #include<fcntl.h> int main() { int fd, count; char ch; fd = open("google.txt",O_RDWR\|O_CREAT); write(fd,"s",1); lseek(fd,0,SEEK_SET); write(fd,"d",1); lseek(fd,0,0); read(fd,&ch,1); printf("%cn",ch); return 0; } a) d b) s c) sd d) none of the mentioned	Tell us what is the output of this program? #include<stdio.h> #include<stdlib.h> #include<fcntl.h> int main() { int fd, count; char ch, buff; buff = (char )malloc(sizeof(char)*10); fd = open("san.c",O_RDONLY); count = read(fd,buff,5); printf("%dn",count); return 0; } a) 5 b) 10 c) 0 d) -1