int main (void) {
// sentinal
int s = 1;
char buf[1024];
struct cmd command;
int fd[2], fdin, fdout,fdinflag = 0,fdoutflag = 0,ndx,mypid;
pid_t pid, pidBG;
while(s) {
// custom cmd line
printf("CMDLINE$-->");
// wil get first line of input
if((gets(buf) == NULL)){
continue;
}
else if(strcmp(buf, "exit") == 0){
s = 0;
continue;
}
// will read into struct
if (cmdscan(buf,&command)){
printf("Illegal Format: \n");
continue;
}
// if there is for redirect_in set a flag
if(command.redirect_in == 1){
if((fdin = open(command.infile, O_RDONLY)) == -1){
perror("fdin");
exit(-1);
}
fdinflag = 1;
}
// if there is for redirect_out set a flag
if(command.redirect_out == 1){
if(command.redirect_append == 1){
if((fdout = open(command.outfile, O_WRONLY | O_APPEND | O_CREAT, 0600)) == -1){
perror("open append");
exit(-1);
}
}
else
{
if((fdout = open(command.outfile, O_WRONLY | O_CREAT | O_TRUNC, 0600)) == -1){
perror("open out");
exit(-1);
}
}
fdoutflag = 1;
}
// if the user wants to pipe do here
if (command.piping) {
if ( command.background == 1){
pipe(fd);
ndx = 0;
switch( fork()){
case -1:
perror("fork error");
exit(-1);
case 0:
switch( fork()){
case -1:
perror("fork error");
exit(-1);
case 0:
ndx = 1;
switch( fork()){
case -1:
perror("fork error");
exit(-1);
case 0:
ndx = 2;
break;
default:
break;
}
default:
exit(0);
}
default:
wait(NULL);
}
// the user does not want to background
}else{
pipe(fd);
ndx = 0;
switch(fork()){
case -1:
perror("fork error");
exit(-1);
case 0:
ndx = 1;
mypid = getpid();
switch(fork()){
case -1:
perror("fork error");
exit(-1);
case 0:
ndx = 2;
break;
default:
break;
}
default:
break;
}
}
if (ndx == 0){
close(fd[0]);
close(fd[1]);
// need to close them in the parent process!!!! why my program kept writing to my out program all the time
if (fdinflag) {
close(fdin);
}
if (fdoutflag) {
close(fdout);
}
waitpid(mypid, NULL, 0);
}
if (ndx == 1){
close(fd[1]);
if (fdoutflag){
dup2(fdout, STDOUT_FILENO);
close(fdout);
}
dup2(fd[0], STDIN_FILENO);
close(fd[0]);
execvp(command.argv2[0], command.argv2);
perror("exec error");
exit(-1);
}
if (ndx == 2){
close(fd[0]);
if (fdinflag){
dup2(fdin, STDIN_FILENO);
close(fdin);
}
dup2(fd[1], STDOUT_FILENO);
close(fd[1]);
execvp(command.argv1[0], command.argv1);
perror("exec error");
exit(-1);
}
} else {
switch(pid = fork()) {
case -1:
perror("fork error");
exit(-1);
case 0:
if (command.background == 1) {
switch(fork()){
case -1:
perror("fork error");
exit(-1);
case 0:
if (fdinflag) {
dup2(fdin,STDIN_FILENO);
close(fdin);
}
if (fdoutflag) {
dup2(fdout,STDOUT_FILENO);
close(fdout);
}
execvp(command.argv1[0],command.argv1);
perror("exec error");
exit(-1);
default:
exit(0);
}
}
else{
if (fdinflag) {
dup2(fdin,STDIN_FILENO);
close(fdin);
}
if (fdoutflag) {
dup2(fdout,STDOUT_FILENO);
close(fdout);
}
execvp(command.argv1[0],command.argv1);
perror("exec error");
exit(-1);
}
default:
if (command.background == 0){
waitpid(pid,NULL,0);
// needed to close the fdins and fdouts because they were still linked to parent processes and therefor all my commands were all being sent to the outfile.
if (fdinflag) {
close(fdin);
}
if (fdoutflag) {
close(fdout);
}
}else {
if (fdinflag) {
close(fdin);
}
if (fdoutflag) {
close(fdout);
}
}
}
}
}
exit(0);
}
int main() {
char buf[BUFSIZE];
pid_t pid, pid1, pid2;
int fd[2];
// get USER name and print
printf("--------- Welcome %s ---------\n",getenv("USER"));
printf("[%s]: ", getenv("USER"));
// while stdin != Null run while loop
while((fgets(buf,BUFSIZE,stdin) != NULL)) {
//if error from cmdscan.c print error and continue
if(cmdscan(buf,&command) == -1) {
printf("ILLEGAL FORMAT\n");
printf("[%s]: ", getenv("USER"));
continue;
}//end if error from cmdscan.c
//if user types exit terminate shell
if(strcmp(command.argv1[0],"exit") == 0) {
exit(0);
}//end if exit
// create first child process
if((pid = fork()) < 0){
perror("FORK ERROR\n");
}//end if fork error check
// if child process
else if (pid == 0) {
//if backgrounding = true create another child process pid2
if (command.background){
pid2 = fork();
if(pid2 < 0){
perror("FORK ERROR\n");
}//end if pid2 error
}//end if backgrounding
//if backgrounding and parent of child pid2 exit
//pid2 is now adopted by init
if(command.background && (pid2 != 0)){
exit(0);
}//end if backgrounding and pid2 !=0
// if not backgrounding or backgrounding and child pid2
if(!command.background || (command.background && pid2 == 0)){
//if piping
if(command.piping){
pipe(fd);
pid1 = fork();
//if pid1 is the parent process
if (pid1 > 0) {
redirectCheck();
close(fd[1]);
dup2(fd[0], STDIN_FILENO);
execvp(command.argv2[0],command.argv2);
}//end if pid1 is parent process
// if pid1 is the child process
else if( pid1 == 0){
redirectCheck();
close(fd[0]);
dup2(fd[1],STDOUT_FILENO);
execvp(command.argv1[0],command.argv1);
}//end else if child process
}//end if piping
//if !piping
if(!command.piping){
redirectCheck();
// error check
if(execvp(command.argv1[0],command.argv1) == -1){
printf("NOT A VALID USAGE\n");
exit(1);
}//end if error check
//execute arguments
execvp(command.argv1[0],command.argv1);
}//end if !piping
exit(0);
}//end if not backgrounding or backgrounding and child pid2
}//end else if child
else {
if(wait(&status) != pid)
perror("WAIT ERROR");
printf("[%s]: ", getenv("USER"));
}//end else
}//end while loop
return 0;
}//end main
int main(){
int stop = 0;
char buf[1024];
struct cmd command;
int i;
int fd[2], fdin, fdout;
pid_t pid, pidBG;
while(!stop){
write(STDOUT_FILENO, ">", 1);
if((gets(buf) == NULL)){
continue;
}
else if(strcmp(buf, "exit") == 0){
stop = 1;
continue;
}
if (cmdscan(buf,&command)){
printf("Illegal Format: \n");
continue;
}
if(command.redirect_in){
if((fdin = open(command.infile, O_RDONLY)) == -1){
perror("fdin");
exit(-1);
}
}
if(command.redirect_out){
if(command.redirect_append){
if((fdout = open(command.outfile, O_WRONLY | O_APPEND | O_CREAT, 0600)) == -1){
perror("open append");
exit(-1);
}
}
else{
if((fdout = open(command.outfile, O_WRONLY | O_CREAT | O_TRUNC, 0600)) == -1){
perror("open out");
exit(-1);
}
}
}
switch(pid = fork()){
case -1:
perror("fork");
exit(-1);
case 0:
if(pipe(fd) == -1){
perror("pipe");
exit(-1);
}
switch(pidBG = fork()){
case -1:
perror("fork2");
exit(-1);
case 0:
close(fd[0]);
if(command.redirect_in){
close(0);
dup(fdin);
close(fdin);
}
if(command.redirect_out && !command.piping){
close(1);
dup(fdout);
close(fdout);
}
else if(command.piping){
dup2(fd[1], STDOUT_FILENO);
}
close(fd[1]);
execvp(command.argv1[0], command.argv1);
perror("execvp arg1");
exit(-1);
break;
default:
if(!command.piping){
exit(0);
}
else{
dup2(fd[0], STDIN_FILENO);
close(fd[0]);
if(command.redirect_out){
close(1);
dup(fdout);
close(fdout);
}
close(fd[1]);
execvp(command.argv2[0], command.argv2);
perror("execvp arg2");
exit(-1);
}
}
default:
if(!command.background){
if(waitpid(pid, NULL, 0) != pid){
perror("waitpid error");
exit(-1);
}
}
}
}
exit(0);
}