Operating System

C programs for file manipulation

MOV

#include<sys/types.h>
#include<sys/stat.h>
#include<stdio.h>
#include<unistd.h>
#include<fcntl.h>
int main( int argc,char *argv[] )
{
int i,fd1,fd2;
char *file1,*file2,buf[2];
file1=argv[1];
file2=argv[2];
printf("file1=%s file2=%s",file1,file2);
fd1=open(file1,O_RDONLY,0777);
fd2=creat(file2,0777);
while(i==read(fd1,buf,1)>0)
write(fd2,buf,1);
remove(file1);
close(fd1);
close(fd2);
}

LS

#include <stdio.h>
#include <dirent.h>
#include <errno.h>
#include <stdlib.h>

void _ls(const char *dir, int op_a, int op_l) {
    // Here we will list the directory
    struct dirent *d;
    DIR *dh = opendir(dir);

    if (!dh) {
        if (errno == ENOENT) {
            // If the directory is not found
            perror("Directory doesn't exist");
        } else {
            // If the directory is not readable then throw error and exit
            perror("Unable to read directory");
        }
        exit(EXIT_FAILURE);
    }

    // While the next entry is not NULL, we will print directory files
    while ((d = readdir(dh)) != NULL) {
        // If hidden files are found and op_a is not set, skip
        if (!op_a && d->d_name[0] == '.')
            continue;

        printf("%s ", d->d_name);
        if (op_l) printf("\n");
    }

    if (!op_l)
        printf("\n");

    closedir(dh);
}

int main(int argc, const char *argv[]) {
    if (argc == 1) {
        _ls(".", 0, 0);
    } else if (argc == 2) {
        if (argv[1][0] == '-') {
            // Checking if option is passed
            // Options supporting: a, l
            int op_a = 0, op_l = 0;
            char *p = (char *)(argv[1] + 1);

            while (*p) {
                if (*p == 'a') op_a = 1;
                else if (*p == 'l') op_l = 1;
                else {
                    perror("Option not available");
                    exit(EXIT_FAILURE);
                }
                p++;
            }

            _ls(".", op_a, op_l);
        }
    }
    return 0;
}