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

{

shell_terminal = STDIN_FILENO;

while (tcgetpgrp (shell_terminal) != (shell_pgid = getpgrp ()))

kill (- shell_pgid, SIGTTIN);

/* Ignore interactive and job-control signals. */

signal (SIGINT, SIG_IGN);

signal (SIGQUIT, SIG_IGN);

signal (SIGTSTP, SIG_IGN);

/* Put ourselves in our own process group. */

shell_pgid = getpid ();

if (setpgid (shell_pgid, shell_pgid) < 0)

{

perror ("Couldn't put the shell in its own process group");

exit (1);

}

/* Grab control of the terminal. */

tcsetpgrp (shell_terminal, shell_pgid);

/* Save default terminal attributes for shell. */

tcgetattr (shell_terminal, &shell_tmodes);

int status=1;

int i, mode = NORMAL, cmdArgc;

size_t len = INPUT_STRING_SIZE;

char *cpt, *inputString, *supplement = NULL;

inputString = (char*)malloc(sizeof(char)*INPUT_STRING_SIZE);

char curDir[100];

home = (char *)malloc(100*sizeof(char));

getcwd(home,100);

char hostname[1024];

gethostname(hostname,sizeof(hostname));

char *username;

username=getenv("USER");

while(1)

{

if(signal(SIGINT,sig_handler)==SIG_ERR)

perror("Signal not caught!!");

int status1;

pid_t t;

mode = NORMAL;

getcwd(curDir, 100);

proc temp3[1024];

proc temp4[1024];

int c=0;

int m=0;

for(c=0;c<no;c++)

{

pid_t pid_result = waitpid(pro[c].id, &status, WNOHANG);

if(kill(pro[c].id,0)==-1 && errno==ESRCH){

printf("Process %s exited whose id is %d\n",pro[c].process,pro[c].id);

printf("YES");

}

else

{

temp3[m]=pro[c];

temp4[m]=jobs[c];

m++;

}

}

no=m;

for(c=0;c<no;c++)

{

pro[c]=temp3[c];

jobs[c]=temp4[c];

}

int len1=strlen(home);

int totallen=strlen(curDir);

int ii;

int flag=0;

char path[100];

for(ii=0;ii<len1;ii++)

if(curDir[ii]!=home[ii])

flag=1;

if(flag==0)

{

for(ii=len1;ii<=totallen;ii++)

path[ii-len1+1]=curDir[ii];

path[0]='~';

}

else

{

for(ii=0;ii<totallen;ii++)

path[ii]=curDir[ii];

}

printf("%s@%s:%s$",username,hostname,path);

getline( &inputString, &len, stdin);

if(strcmp(inputString, "exit\n") == 0)

exit(0);

char **args2;

args2=split(inputString,";");

for(i=0;args2[i]!=NULL;i++)

{

cmdArgc = parse(args2[i], cmdArgv, &supplement, &mode);

if(strcmp(*cmdArgv, "cd") == 0)

{

cd(cmdArgv);

}

else if(strcmp(*cmdArgv, "") == 0)

{

continue;

}

else if(strcmp(*cmdArgv, "pwd") == 0)

{

pwd();

}

else if(strcmp(*cmdArgv, "echo") == 0)

{

echo(cmdArgv,cmdArgc);

}

else if(strcmp("pinfo",*cmdArgv)==0)

{

FILE *fp;

char buf1[256],buf2[256];

int pid;

char name[256],state;

long unsigned int size;

if(cmdArgc==1)

{

sprintf(buf1,"/proc/%d/stat",getpid()); //open the stat and exe files

sprintf(buf2,"/proc/%d/exe",getpid());

}

else

{

sprintf(buf1,"/proc/%s/stat",(cmdArgv[1]));

sprintf(buf2,"/proc/%s/exe",(cmdArgv[1]));

}

if((fp=fopen(buf1,"r"))!=NULL)

{

/*scan the stat file*/

fscanf(fp,"%d %*s %c %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %lu %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d",&pid,&state,&size);

fclose(fp);

printf("pid -- %d\nProcess Status -- %c\nmemory -- %lu\n",pid,state,size);

readlink(buf2,name,256);

printf("Executable Path -- %s\n",name);

}

else

perror("No such process");

}

else

execute(cmdArgv, mode, &supplement);

}

}

return 0;

}