Linux? Open Source? Bah!

[Afgncaap5]

Okay, maybe the conversation is a little bitter....but man, I couldn't for the life of me find the code that runs a standard Linux terminal!

I mean, you'd think that'd be one of the important parts of the source files. But for all my searching, I can't find it.

Can someone with more experience with Linux point me to where such mystical documentation might exist? If I'm going to look into this "open source" stuff, gosh darn it the source better actually be open.

-EDIT-

And in the event that "terminal" is being too vague, I'm talking about the Command Line. The part that looks kinda like DOS.

[Mitchell]

Isn't the command prompt part of the kernel? The entire kernel should be found here: www.kernel.org/

[Afgncaap5]

Hmmm...I've already been there, but I couldn't find anything. Maybe I'm just not looking hard enough.

[Mitchell]

What exactly are you trying to do?

[Afgncaap5]

Well, I'm basically looking for the code that intrprets commands, plus a little extra. The commands that interpret | to mean piping, the commands that read >, <, and >> as I/O redirection, and the commands that know how to background programs when & is typed.

I'm basically looking to create my own dumbed down version of such stuff...but before I can start doing that I need to see what works now.

[Mitchell]

Still writing in C? You might want to try getpot: getpot.sourceforge.net/

[Afgncaap5]

Oh, man...I needed this two weeks ago. Thanks, Mitchell! :-)

It's crazy hectic, let's see if I can show what I've got at the moment....

#include <sys/wait.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/utsname.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <fcntl.h>
#include <sys/stat.h>

#define MAXARGS 64
#define BUFLEN 81

struct buffer_t{
char linebuf[BUFLEN+1];
char *arglist[MAXARGS];
};

struct buffer_t buffer;

int main(int argc, char * argv[]){
int pid, bkg;
char *(args[MAXARGS+1]);
char **args2;

while(1){
/*check_exit_status(); goes here*/

printf("JML>");
bkg = find_background(args);

if(fgets(buffer.linebuf, BUFLEN, stdin) == NULL) break;
if(!parse_args(buffer.linebuf, args)) continue;

/* if(find_pipe(args, &args2)){ run_piped_children(args,
args2, bkg); } */

else{
if((pid=fork()) == -1) perror("fork");
else if(pid == 0) childproc(args);
else parentproc(pid, bkg);
}//end else
}//end while
exit(0);
} // end main

//int find_pipe

int parse_args(args){
char whitespace[] = " \t\n\r";
int nargs;

nargs = 0;
buffer.arglist[nargs] = strtok(buffer.linebuf, whitespace);
while (buffer.arglist[nargs] != NULL){
buffer.arglist[++nargs] = strtok(NULL, whitespace);
}//end while
return 1;
}//end parse_args

int internal_command(args){
extern char **environ;
if(strcmp(buffer.arglist[0], "environ")==0){
char **envp = environ;
while (*envp){
printf("%s\n", *envp++);
}//end while
return 1;
}//end if

else if(strcmp(buffer.linebuf, "path")==0){
char *envpath;
envpath=getenv("PATH");
printf("PATH:\n");
printf("%s\n", envpath);
return 1;
}//end else if

else if(strcmp(buffer.linebuf, "exit")==0){
exit(0);
}//end else if

return 0;
}//end internal_command

int childproc(args){
int err;
int nargs=0;
int tempfd;
int i;
err=execvp(buffer.linebuf, buffer.arglist);

for (i = 0; buffer.arglist != NULL; i++)
if (strcmp(buffer.arglist, "<") == 0) {
i++;
tempfd = open(buffer.arglist, O_RDONLY, 0);
/*CHECK FOR ERRORS HERE*/
close(0);
dup2(tempfd, 0);
close(tempfd);
}
if (strcmp(buffer.arglist, ">") == 0) {
i++;
tempfd = open(buffer.arglist, O_WRONLY|O_CREAT|O_TRUNC, S_IRUSR|S_IWUSR);
/*CHECK FOR ERRORS HERE*/
close(1);
dup2(tempfd, 1);
close(tempfd);
}
if (strcmp(buffer.arglist, ">>") == 0) {
//SHOULD APPEND, NOT CHANGE STANDARD ERROR! CHANGE QUICKLY!
i++;
tempfd = open(buffer.arglist, O_WRONLY|O_CREAT|O_APPEND, S_IRUSR|S_IWUSR);
/*CHECK FOR ERRORS HERE*/
close(2);
dup2(tempfd, 2);
close(tempfd);
}

return 1;
} // end childproc

int parentproc(pid, bkg){
int status = 0; // Not sure about status...
pid = waitpid(-1, &status, WNOHANG);

if (pid == -1)
//status is requested for child process
; //Just so that the computer's not confused
else if (pid > 0)
//pid specifies the pid of the child process for which status is requested
;
else if (pid == 0)
//status is requested for any child process whose process group ID is
//equal to that of the calling process.
;
else if (pid < -1)
//status is requested for any child process whose process group ID is
//equal to the absolute value of pid.
;

/* How non-backgrounding did it...

while (wait(&bkg) != pid);
return 1;

*/
}//end parentproc

int find_background(args){
//Returns 1 if the process is to be backgrounded,
//0 if it is not. Backgrounding is signified with
// an ampersand, "&".
int j;
for (j = 0; buffer.arglist != NULL; j++) {
if (strcmp(buffer.arglist[j], "&") == 0) {
return 1;
}
else
j++;
}
return 0;
} //end find_background

[Afgncaap5]

That's where I ran into a stumbling block after looking at that link of yours. I can't figure out how to proceed from here, and as it is the code just dumps the core.