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rubysh.c
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rubysh.c
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#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <stdbool.h>
#include <ctype.h>
#include <time.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <sys/wait.h>
#include <dirent.h>
#include <errno.h>
#include <regex.h>
#define _XOPEN_SOURCE 500
#define _POSIX_C_SOURCE 200809L
int execute(char *, char *);
void ruby_listener();
//global job id
int job_id = 1;
//variable to store the current working directory
char pwd[1000];
//current foreground command
char *cur_fg_cmd;
//current foreground process
int cur_fg_pid = -1;
//background process group
int bg_pgrp = -1;
//current foreground pid
int cur_bg_pid = -1;
//flag for time
bool global_time_flag = false;
//current background command
char *cur_bg_command;
//variable to indicate whether prompt needs to be shown
int prompt_disp = 0;
//global variable to indicate latest job_id
int latest_jobid = -1;
//variable to indicate whether parent process can wait for the child to complete
int can_wait = 1;
//process structure
typedef struct proc_info {
pid_t pid;
int jid;
int status;
char *command;
struct proc_info *next;
} proc_info;
//history structure
typedef struct history_info {
char *command;
struct history_info *next;
} history_info;
//list of histories
typedef struct history_list {
history_info *head, *tail;
int size;
} history_list;
//process jobs list
typedef struct pjid_list {
proc_info *head, *tail;
int size;
} pjid_list;
history_info *init_history_info(history_info *node, char *command) {
node = (history_info *) malloc(sizeof(history_info));
node->command = (char *) malloc(sizeof(char));
strcpy(node->command, command);
node->next = NULL;
return node;
}
//init proc_info
proc_info *init_proc_info(proc_info *node, pid_t pid, int jid, int status, char *command) {
node = (proc_info *) malloc(sizeof(proc_info));
node->pid = pid;
node->jid = jid;
node->status = status;
node->command = (char *) malloc(sizeof(char));
strcpy(node->command, command);
node->next = NULL;
return node;
}
history_list *init_history_list(history_list *hist) {
hist = (history_list *) malloc(sizeof(history_list));
hist->head = NULL;
hist->tail = NULL;
hist->size = 0;
return hist;
}
//init process list
pjid_list *init_pjid_list(pjid_list *l) {
l = (pjid_list *) malloc(sizeof(pjid_list));
l->head = NULL;
l->tail = NULL;
l->size = 0;
return l;
}
void insert_history(history_list *hist, char *command) {
if (hist->head == NULL) {
history_info *new_node;
new_node = init_history_info(new_node, command);
hist->head = new_node;
hist->tail = new_node;
} else {
history_info *temp = hist->head;
while (temp->next != NULL) {
temp = temp->next;
}
history_info *new_node;
new_node = init_history_info(new_node, command);
temp->next = new_node;
hist->tail = new_node;
}
++hist->size;
}
//insert information for a new process to the linked list
void insert(pjid_list *l, pid_t pid, int jid, int status, char *command) {
if (l->head == NULL) {
proc_info *new_node;
new_node = init_proc_info(new_node, pid, jid, status, command);
l->head = new_node;
l->tail = new_node;
} else {
proc_info *temp = l->head;
while (temp->next != NULL) {
temp = temp->next;
}
proc_info *new_node;
new_node = init_proc_info(new_node, pid, jid, status, command);
temp->next = new_node;
l->tail = new_node;
}
++l->size;
}
//check whether the process list is empty
int is_empty(pjid_list *l) {
if (l->head == NULL) return 1;
return 0;
}
//search whether process given by pid is present in the process list
int search(pjid_list *l, int pid) {
if (l->head == NULL) {
return 0;
} else {
proc_info *temp = l->head;
while (temp->next != NULL) {
if (temp->pid == pid) {
return 1;
}
temp = temp->next;
}
if (temp->pid == pid) return 1;
return 0;
}
}
int extract_integer(char *str) {
char *p = str;
int val = 0;
while (*p) { // While there are more characters to process...
if (isdigit(*p)) { // Upon finding a digit, ...
val = (int) strtol(p, &p, 10); // Read a number, ...
} else { // Otherwise, move on to the next character.
p++;
}
}
// printf("%d\n",val);
return val;
}
double get_double(char *str) {
/* First skip non-digit characters */
/* Special case to handle negative numbers */
str = strrchr(str, (char) 32);
while (*str && !(isdigit(*str) || ((*str == '-' || *str == '+') && isdigit(*(str + 1)))))
str++;
/* The parse to a double */
return strtod(str, NULL);
}
void print_n_histories(history_list *hist, char *line) {
history_info *temp = hist->head;
long long int history_cnt = 1;
int val = extract_integer(line);
if (val > hist->size) {
printf("%s\n", "Command history non-existent");
} else {
while (temp->next != NULL) {
if (history_cnt == hist->size - (val)) {
// printf("%s %s\n", "Executing command", temp->command);
while (temp->next != NULL) {
printf("%s\n", temp->command);
temp = temp->next;
}
break;
} else {
temp = temp->next;
history_cnt++;
}
}
}
}
char *print_history_item(history_list *hist, char *line, short z) {
history_info *temp = hist->head;
long long int history_cnt = 1;
int val = extract_integer(line);
if (val > hist->size) {
if (z == 1) {
printf("%s\n", "History non-existent");
return NULL;
} else {
printf("%s\n", "Command history non-existent");
return NULL;
}
} else {
while (temp->next != NULL) {
if (history_cnt == val) {
if (z == 1) {
printf("%s\n", temp->command);
return temp->command;
} else {
// printf("%s %s\n", "Executing command", temp->command);
return temp->command;
}
} else {
temp = temp->next;
history_cnt++;
}
}
}
}
//retrieve process command
char *get_command(pjid_list *l, int id) {
if (l->head == NULL) {
return NULL;
}
proc_info *temp = l->head;
while (temp->next != NULL) {
if (temp->pid == id || temp->jid == id) {
return temp->command;
}
temp = temp->next;
}
if (temp->pid == id || temp->jid == id) {
return temp->command;
}
return NULL;
}
void retrieve_all_histories(history_list *h) {
history_info *temp = h->head;
long long int history_cnt = 0;
while (temp->next != NULL) {
++history_cnt;
printf(" %lli %s\n", history_cnt, temp->command);
temp = temp->next;
}
}
/* Bugs- more than two nested issue statements not working
Although implemented , check */
char *retrieve_issue_cmd(history_list *h, char *command) {
char *array[h->size - 1];
history_info *temp = h->head;
int i = 0;
while (temp->next != NULL) {
array[i] = malloc(strlen(temp->command) * sizeof(char));
strcpy(array[i], temp->command);
++i;
temp = temp->next;
}
strcpy(command, array[extract_integer(command) - 1]);
for (int i = 0; i < h->size - 1; ++i) {
/* code */
free(array[i]);
}
return command;
}
//delete information for a process from the process list
void delete(pjid_list *l, pid_t pid) {
if (l->head == NULL) {
return;
} else if (pid == -1) return;
else if (search(l, pid) == 0) { return; }
else if (l->head == l->tail) {
if (l->head->pid == pid) {
proc_info *temp = l->head;
l->head = NULL;
l->tail = NULL;
free(temp);
} else return;
} else if (l->head->pid == pid) {
proc_info *temp = l->head;
l->head = l->head->next;
temp->next = NULL;
free(temp);
} else {
proc_info *temp = l->head;
proc_info *prev = temp;
while (temp->next != NULL && temp->pid != pid) {
prev = temp;
temp = temp->next;
}
if (temp->pid == pid) {
if (temp == l->tail) {
prev->next = NULL;
l->tail = prev;
free(temp);
} else {
prev->next = temp->next;
temp->next = NULL;
free(temp);
}
} else return;
}
l->size--;
}
//retrieve reference to the process given by id (this can be either pid or jid)
proc_info *get_proc(pjid_list *l, int id) {
if (l->head == NULL) {
return NULL;
}
if (l->head->jid == id || l->head->pid == id) {
return l->head;
}
proc_info *temp = l->head;
while (temp->next != NULL) {
if (temp->jid == id || temp->pid == id) {
return temp;
}
temp = temp->next;
}
if (temp->jid == id || temp->pid == id) {
return temp;
}
return NULL;
}
//update status for a process
void update(proc_info *cur, pid_t pid, int status) {
if (cur == NULL) {
return;
}
if (cur->pid == pid) {
cur->status = status;
return;
}
update(cur->next, pid, status);
}
//remove information for all processes from the process list
void clear(pjid_list *l) {
if (l->size == 0) {
return;
}
proc_info *temp = l->head;
while (temp != l->tail) {
proc_info *del_node = temp;
temp = temp->next;
}
cur_fg_pid = -1;
job_id = 0;
}
//global reference to the linked list
pjid_list *l;
//global reference to history list
history_list *hist;
//extract job id from command
int get_job_id(char *line) {
char *line1 = (char *) malloc(sizeof(char));
char *token;
char **tokens = (char **) malloc(sizeof(char *));
int job_id, i;
strcpy(line1, line);
token = strtok(line1, "%");
i = 0;
while (token != NULL && strlen(token) > 0) {
tokens[i] = token;
i = i + 1;
token = strtok(NULL, "%");
}
tokens[i] = NULL;
job_id = atoi(tokens[1]);
free(line1);
return job_id;
}
//retrieve command line input
char *command_extractor(void) {
char *line = NULL;
size_t bufsize = 0;
getline(&line, &bufsize, stdin);
insert_history(hist, line);
return line;
}
//check whether command is a foreground command using regex
int is_fg(char *line) {
regex_t regex2;
regex_t regex3;
int reti3, reti4;
/* Compile regular expression */
reti3 = regcomp(®ex2, "^[[:space:]]*fg[[:space:]]+%[[:space:]]*[[:digit:]]+[[:space:]]*$", REG_EXTENDED);
reti4 = regcomp(®ex3, "^[[:space:]]*fg[[:space:]]*$", REG_EXTENDED);
if (reti3) {
return -1;
}
if (reti4) {
return -1;
}
reti3 = regexec(®ex2, line, 0, NULL, 0);
if (!reti3) {
int job_id = get_job_id(line);
return job_id;
} else if (reti3 == REG_NOMATCH) {}
else {
return -1;
}
reti4 = regexec(®ex3, line, 0, NULL, 0);
if (!reti4) {
return latest_jobid;
} else if (reti4 == REG_NOMATCH) {
return -1;
} else {
return -1;
}
}
//check whether command is a background command using regex
int is_bg(char *line) {
if (line[strlen(line) - 1] == '&') return -2;
regex_t regex, regex1;
int reti1, reti2;
/* Compile regular expression */
reti1 = regcomp(®ex, "^[[:space:]]*bg[[:space:]]+%[[:space:]]*[[:digit:]]+[[:space:]]*$", REG_EXTENDED);
reti2 = regcomp(®ex1, "[[:space:]]*^bg[[:space:]]*$", REG_EXTENDED);
if (reti1) {
return -1;
}
if (reti2) {
return -1;
}
reti1 = regexec(®ex, line, 0, NULL, 0);
if (!reti1) {
int job_id = get_job_id(line);
return job_id;
} else if (reti1 == REG_NOMATCH) {}
else {
return -1;
}
reti2 = regexec(®ex1, line, 0, NULL, 0);
if (!reti2) {
return latest_jobid;
} else if (reti2 == REG_NOMATCH) {
return -1;
} else {
return -1;
}
}
//handler for Ctrl-Z (SIGTSTP signal)
void custom_made_sigtstp_handler(int signo) {
can_wait = 0;
if (cur_fg_pid == -1) {
return;
}
//sending SIGSTP signal to the current foreground process
int r = kill(cur_fg_pid, SIGTSTP);
if (r == -1) {
perror("\nerror");
} else {
printf("\n[%d]+ \tStopped", job_id);
if (search(l, cur_fg_pid) == 0) {
insert(l, cur_fg_pid, job_id, 3, cur_fg_cmd);
latest_jobid = job_id;
++job_id;
} else {
update(l->head, cur_fg_pid, 3);
latest_jobid = get_proc(l, cur_fg_pid)->jid;
}
cur_fg_pid = -1;
cur_fg_cmd = NULL;
}
//flushing standard output
fflush(stdout);
return;
}
//handler for Ctrl-C (SIGINT signal)
void custom_made_sigint_handler(int sig_number) {
can_wait = 0;
if (cur_fg_pid != -1) {
kill(cur_fg_pid, SIGKILL);
} else {
delete(l, cur_fg_pid);
}
latest_jobid = -1;
cur_fg_pid = -1;
cur_fg_cmd = NULL;
char *prompt_name = "\nabsgibson:";
char new_prompt_name[strlen(prompt_name) + strlen(pwd) + 2];
strcpy(new_prompt_name, prompt_name);
strcat(new_prompt_name, pwd);
strcat(new_prompt_name, "> ");
fwrite(new_prompt_name, sizeof(char), strlen(new_prompt_name) + 1, stdout);
prompt_disp = 1;
fflush(stdout);
return;
}
//send process to foreground process group (either from suspended state of from background process group)
int send_to_fg(int jid) {
proc_info *p = get_proc(l, jid);
if (p == NULL) {
return -1;
}
if (p->status == 3) {
p->status = 1;//changing the status of the process to foreground
kill(p->pid, SIGCONT);
cur_fg_pid = p->pid;
cur_fg_cmd = p->command;
setpgid(cur_fg_pid, getpgrp());
int status;
int k;
while (can_wait == 1 && (k = kill(p->pid, 0)) == 0);
if (errno == EPERM) { perror("error"); }
if (p->status != 3 && can_wait == 1) {
kill(cur_fg_pid, SIGKILL);
printf("\n[%d] done!\t%s\n", p->jid, p->command);
delete(l, cur_fg_pid);
latest_jobid = -1;
}
cur_fg_pid = -1;
cur_fg_cmd = NULL;
prompt_disp = 0;
return 1;
} else if (p->status == 2) {
p->status = 1;
cur_fg_pid = p->pid;
setpgid(cur_fg_pid, getpgrp());
int status;
int k;
//need to wait on that process
while (can_wait == 1 && (k = kill(p->pid, 0)) == 0);
if (errno == EPERM) { perror("error"); }
//if still foreground and can wait (this means that the process has completed execution and needs to be killed)
if (can_wait == 1 && p->status == 1) {
kill(cur_fg_pid, SIGKILL);
proc_info *p = get_proc(l, cur_fg_pid);
printf("\n[%d] done!\t%s\n", p->jid, p->command);
delete(l, cur_fg_pid);
}
cur_bg_pid = -1;
latest_jobid = -1;
free(cur_bg_command);
tcsetpgrp(STDIN_FILENO, getpid());
return 1;
}
return -1;
}
//send process to background process group from suspended state
int send_to_bg(int jid) {
proc_info *p = get_proc(l, jid);
//if jobid invalid
if (p == NULL) {
return -1;
}
//only a suspended can be continued in background
if (p->status != 3) {
return -1;
}
//need to change the process group of the process to the background process group and then need to send a SIGCONT signal to the process. We return back to the prompt immediately and don't wait.
setpgid(p->pid, bg_pgrp);
cur_bg_pid = p->pid;
int k = kill(p->pid, SIGCONT);
if (k == -1) {
perror("error");
return -1;
}
update(p, p->pid, 2);
return 1;
}
//execute process in the background
int execute_bg(char *path, char *command) {
int child = fork();
if (child < 0) {
return 0;
}
if (child == 0) {
char *args[4];
args[0] = path;
args[1] = "-c";
args[2] = command;
args[3] = (char *) 0;
execvp(path, args);
} else {
//pid of background process will be one more than the child process
int bg_pid = child + 1;
if (bg_pgrp == -1) {
setpgid(bg_pid, 0);
bg_pgrp = bg_pid;
} else {
setpgid(bg_pid, bg_pgrp);
}
insert(l, bg_pid, job_id, 2, command);//background status = 2
printf("[%d] %d\n", job_id, bg_pid);
latest_jobid = job_id;
cur_bg_pid = bg_pid;
if (cur_bg_command == NULL) { cur_bg_command = (char *) malloc(sizeof(char)); }
strcpy(cur_bg_command, command);
++job_id;
}
}
//executing any unrecognized command
int execute(char *path, char *command_line) {
//checking whether the command is of type 'cd'
char *command_type = (char *) malloc(sizeof(char));
int i = 0;
//retrieving the type of the command
for (i = 0; command_line[i] != ' ' && command_line[i] != '\0'; i++) {
command_type[i] = command_line[i];
}
if (strcmp(command_type, "cd") == 0) {
int is_just_cd = 0;
if (strcmp(command_line, "cd") == 0 || strcmp(command_line, "cd ") == 0 || strcmp(command_line, "cd ") == 0) {
is_just_cd = 1;
}
char *dir_path = strrchr(command_line, ' ') + 1;
int r;
if (is_just_cd == 1) {
r = chdir(getenv("HOME"));
} else {
r = chdir(dir_path);
}
if (r < 0) {
perror("error");
return -1;
}
//updating the present working directory. Will use pwd to append to prompt
strcpy(pwd, getcwd(pwd, 1000));
} else {
int child_pid = fork();
if (child_pid < 0) {
perror("ERROR: could not fork process.\n");
}
if (child_pid == 0) {
char *args[4];
args[0] = path;
args[1] = "-c";
args[2] = command_line;
args[3] = (char *) 0;
//executing the command
int exec_return = execvp(path, args);
if (exec_return == -1) {
perror("error: command execution failed!\n");
} else {
exit(exec_return);
}
} else {
//assigning cur_fg_pid to the child
cur_fg_pid = child_pid + 1;
if (cur_fg_cmd == NULL) { cur_fg_cmd = (char *) malloc(sizeof(char)); }
strcpy(cur_fg_cmd, command_line);
int exit_status;
while (can_wait == 1 && waitpid(child_pid, &exit_status, WUNTRACED) > 0) {}
if(exit_status==31744)
{
printf("\n%s\n","Process aborted due to timeout" );
}
cur_fg_pid = -1;
cur_fg_cmd = NULL;
if (can_wait == 1) latest_jobid = -1;
}
}
return 1;
}
char *concat(const char *s1, const char *s2) {
const size_t len1 = strlen(s1);
const size_t len2 = strlen(s2);
char *result = malloc(len1 + len2 + 1);//+1 for the null-terminator
memcpy(result, s1, len1);
memcpy(result + len1, s2, len2 + 1);//+1 to copy the null-terminator
return result;
}
//dispatch the command to any one of functions for execution.
void executor(char *line) {
int fg_jobid = is_fg(line);
int bg_jobid = is_bg(line);
if (fg_jobid == -1) {
if (bg_jobid == -1) {
execute("/bin/sh", line);
return;
} else if (bg_jobid == -2) {
if (execute_bg("/bin/sh", line) == 0) {
perror("error");
}
} else {
if (send_to_bg(bg_jobid) == -1) {
printf("No such process!\n");
}
return;
}
} else {
if (send_to_fg(fg_jobid) == -1) {
printf("No such process!\n");
}
return;
}
}
void removeSubstring(char *s, const char *toremove) {
while (s = strstr(s, toremove))
memmove(s, s + strlen(toremove), 1 + strlen(s + strlen(toremove)));
}
static void remove_leading_spaces(char **line) {
int i;
for (i = 0; (*line)[i] == ' '; i++);
*line = *line + i;
}
char *trim(char *str) {
size_t len = 0;
char *frontp = str;
char *endp = NULL;
if (str == NULL) { return NULL; }
if (str[0] == '\0') { return str; }
len = strlen(str);
endp = str + len;
/* Move the front and back pointers to address the first non-whitespace
* characters from each end.
*/
while (isspace((unsigned char) *frontp)) { ++frontp; }
if (endp != frontp) {
while (isspace((unsigned char) *(--endp)) && endp != frontp) {}
}
if (str + len - 1 != endp)
*(endp + 1) = '\0';
else if (frontp != str && endp == frontp)
*str = '\0';
/* Shift the string so that it starts at str so that if it's dynamically
* allocated, we can still free it on the returned pointer. Note the reuse
* of endp to mean the front of the string buffer now.
*/
endp = str;
if (frontp != str) {
while (*frontp) { *endp++ = *frontp++; }
*endp = '\0';
}
return str;
}
//constantly listen to command line input and send the input to executor for execution
void ruby_listener() {
char *line;
int status = 1;
char ***args;
int i, j;
do {
can_wait = 1;
prompt_disp = 0;
//updating the prompt display to show the current working directory
if (prompt_disp == 0) {
char *prompt_name = "\nabsgibson:";
char new_prompt_name[strlen(prompt_name) + strlen(pwd) + 2];
strcpy(new_prompt_name, prompt_name);
strcat(new_prompt_name, pwd);
strcat(new_prompt_name, "> ");
printf("\n%s", new_prompt_name);
prompt_disp = 1;
}
//fetching command
line = command_extractor();
char temp[strlen(line) + 1];
strcpy(temp, line);
temp[strlen(temp) - 1] = '\0';
line = temp;
if (strcmp(line, "exit") == 0) {
status = 0;
clear(l);
exit(EXIT_SUCCESS);
}
//Code for command history
if (strcmp(trim(line), "history") == 0) {
retrieve_all_histories(hist);
}
/* Code for command history n.*/
else if (strstr(trim(line), "history") != NULL && strcmp(trim(line), "history") != 0) {
// print_history_item(hist,line,1);
print_n_histories(hist, line);
}
/* code for issue n */
else if (strstr(line, "issue") != NULL) {
char *tempo = print_history_item(hist, line, 0);
char assign[strlen(tempo) + 1];
strcpy(assign, tempo);
assign[strlen(tempo) - 1] = '\0';
tempo = assign;
if (tempo != NULL) {
if (strcmp(tempo, "history") == 0) {
retrieve_all_histories(hist);
} else if (strstr(tempo, "history") != NULL && strcmp(tempo, "history") != 0) {
// print_history_item(hist, tempo, 1);
print_n_histories(hist, tempo);
} else if (strstr(tempo, "issue") != NULL) {
char *rob = retrieve_issue_cmd(hist, tempo);
executor(rob);
} else
executor(tempo);
} else {
printf("%s\n", "No such command exists");
}
}
//Cool custom comand rmp (flags -e1 && -e2)
else if (strstr(line, "rmp") != NULL) {
char *p = strrchr(line, ' ');
// printf("%s\n",buffer);
if (strstr(line, "-e1") != NULL) {
if (p && *(p + 1)) {
executor(concat("rm $(ls -I \"*.", concat(p + 1, "\")")));
// executor("rm -f rob.txt");
}
} else if (strstr(line, "-e2") != NULL) {
char *md = strstr(line, "-e2");
removeSubstring(md, "-e2");
executor(concat(concat("mv ", md), " ../"));
executor("rm -f *");
char assign[strlen(pwd)];
strcpy(assign, pwd);
executor("cd ..");
// printf("%s\n",assign );
char *p = strrchr(assign, '/');
p++;
executor(concat(concat("mv ", md), concat(" ", p)));
executor(concat("cd ",p));
}
// fclose(fp);
// free(buffer);
}
//Code for <program_name> n
else if (isdigit(line[strlen(trim(line)) - 1]) && strstr(line,"mkdir ")==NULL && strstr(line,"cd ")==NULL && strstr(line,"touch ")==NULL && strstr(line,"rm ")==NULL) {
global_time_flag = true;
double val = get_double(line);
char *md = trim(line);
int i = strlen(md) - 1;
while (isdigit(md[i]) || (isdigit(md[i - 1]) && md[i] == '.')) {
md[i] = '\0';
--i;
}
// printf("%s\n",md );
// printf("%lf\n",val);
char *buff = malloc(40 * sizeof(char));
sprintf(buff, "%lf", val);
executor(concat(concat("timeout ", buff), concat(" ", md)));
}
//Code for all other basic bash commands
else {
global_time_flag = false;
executor(line);
}
} while (status);
}
//Cool welcome message
void
print_login_message() {
printf(" __\n");
printf(" ___ | \"---.\n");
printf(" .\" \". -o) | |\n");
printf("<|_______|/` |__,---;\n");
printf(" UU UU ====|_______|\n");
printf("Welcome to Ruby shell.\n");
}
int main() {
//initializing the pjid_list
l = init_pjid_list(l);
hist = init_history_list(hist);
//clearing the screen
execute("/bin/sh", "clear");
//specifying a signal handler
signal(SIGINT, custom_made_sigint_handler);
signal(SIGTSTP, custom_made_sigtstp_handler);
//initializing present_working_directory
strcpy(pwd, getcwd(pwd, 1000));
print_login_message();
ruby_listener();
return 0;
}