Can a linked list be sorted by changing the references?

Question

I'm trying to sort a linked list using bubble sort algorithm, by changing the references of nodes. I have searched through a lot of books and on the internet, but I have only found sort methods that changes the values from the information part between nodes. What I want to do is sorting by changing the order of traveling the list, not the values between them. Here's my code. PS: The sort algorithm does not work. It's not duplicate of merge sort list, because it's entirely another algorithm.

#include <stdio.h>
#include <malloc.h>
#include <string.h>
#include <stdlib.h>
#define LINESIZE 128
struct Student {
    float medie;
    char nrMatricol[10];
    char *nume;
    char facltate[6];
};
struct Nod{
    Student stud;
    Nod* next;
};
Nod* inserareNodEnd(Nod *l,Student st)
{
    Nod *nou = (Nod*)malloc(sizeof(Nod));
    nou->next = NULL;//NOU->NEXT=0
    nou->stud = st;
    if (!l) {
        //lista este goala
        return nou;
    }
    else
    {
     //lista contine un nod
        Nod *t = l;
        while (t->next) {
            t = t->next;
        }
        t->next = nou;
        return l;
    }

}
float medieStudenti(Nod *lista) {
    float suma=0;
    int i=0;
    Nod *aux=lista;
    while (aux->next) {
        aux = aux->next;
        suma += aux->stud.medie;
        i++;
    }
    return suma/i;
}
Nod *stergerePrimulNodLista(Nod *l,Student *st) {
    if (l) {
        Nod *aux = l;
        l = l->next;
        aux->next = NULL;
        *st = aux->stud;
        //aux->next = NULL;
        free(aux);

    }
        return l;
}
Nod* sortareLista(Nod *l) {
    Nod *i=l;
    Nod *j=l;
    Nod *aux=l;
    Nod *min=l;
    min = i;
    while (i->next) {

        if (i->stud.medie < min->stud.medie) {
            min = i;
        }
        i = i->next;

    }
    i = l;
    int n = 0;
    while (i->next) {
        j = i->next;
        while (j->next) {
            if (i->stud.medie > j->stud.medie) {
                aux = i->next;
                i->next = j->next;
                j->next = aux;
            }
            j = j->next;
        }
        i = i->next;
    }

    return min;
    //return l;
}
void dezalocare(Nod *lista) {
    Nod *aux;
    aux = lista;
    while (aux->next) {
        lista = aux->next;
        free(aux->stud.nume);
        free(aux);
        aux = lista;
    }
}
void main()
{
    FILE *f;
    Student s;
    Nod *list=NULL;
    f = fopen("fisier.txt", "r");
    char fileBuff[LINESIZE], SEPARATORI[] = { "," };
    char *token;
    while (fgets(fileBuff, LINESIZE, f)) {
        token = strtok(fileBuff, SEPARATORI);
        strcpy(s.nrMatricol, token);
        //extragere token nume student din aceeasi linie
        //salvata in file Buff
        token = strtok(NULL, SEPARATORI);
        s.nume = (char*)malloc(sizeof(char)*strlen(token) + 1);
        strcpy(s.nume, token);
        token = strtok(NULL, SEPARATORI);
        strcpy(s.facltate, token);
        //extragere tokeni medie si conversia tokenului la float
        token = strtok(NULL, SEPARATORI);
        s.medie = atof(token);
        list = inserareNodEnd(list, s);
        printf("%s %s \n", s.nrMatricol, s.nume);
    }
    Nod *tmp = list;
    while (tmp) {
        printf("\nSe afiseaza din lista");
        printf("%s %s \n", tmp->stud.nrMatricol, tmp->stud.nume);
        tmp = tmp->next;
    }

    fclose(f);
    //determinarea mediei pentru studentii din lista
    float media = medieStudenti(list);
    printf("\nMedia este %.2f", media);
    //sortare lista dupa medie(cu modificarea adreselor de legatura)

    //tema dezalocare lista
    //tema dezalocari la nivel de aplicatie
    printf("\nAcesta este Ionel %s %s \n", s.nrMatricol, s.nume);
//  list = stergerePrimulNodLista(list, &s);
    tmp = list;
    while (tmp) {
        printf("\nSe afiseaza din lista");
        printf("%s %s \n", tmp->stud.nrMatricol, tmp->stud.nume);
        tmp = tmp->next;
    }

     tmp = list;
    while (tmp) {
        printf("\nSe afiseaza  lista sortata");
        printf("%s %s \n", tmp->stud.nrMatricol, tmp->stud.nume);
        tmp = tmp->next;
    }
    dezalocare(list);
  }

Answer 1

As requested by original poster, example of a bubble sort for linked list.

Update - removed swap, using pnEnd (ptr to end of unsorted list) instead.

/* bubble sort linked list */

NODE * SortList(NODE *pHead)    /* pHead used as local ptr to start of list */
{
NODE *pEnd = NULL;              /* ptr to end of unsorted part of list */
NODE *pnEnd;                    /* pEnd for next pass */
NODE *pNext;                    /* ptr to next node */
NODE **ppCurr;                  /* ptr to ptr to curr node */
    if(pHead == NULL)           /* return if empty list */
        return pHead;
    do{
        ppCurr = &pHead;        /* set ppCurr to start of list */
        pnEnd = pHead->next;    /* set pnEnd to 2nd node */
        while((pNext = (*ppCurr)->next) != pEnd){
            if((*ppCurr)->data > pNext->data){ /* if out of order swap */
                (*ppCurr)->next = pNext->next;
                pnEnd = pNext->next = *ppCurr;
                *ppCurr = pNext;
            }
            ppCurr = &(*ppCurr)->next;
        }
        pEnd = pnEnd;           /* update pEnd since rest of list is sorted */
    }while(pEnd != pHead->next);
    return pHead;
}