propre

int fds[2];
    pipe(fds);

    if(fork()==0){
        int n;
        char buff[MAX];
        close(fds[0]);
        while((n=read(0,buff,MAX))){
            int i;
            for(i=0;i<n;i++){
                buff[i]=tolower(buff[i]);
            }
            write(fds[1],buff,n);
        }
    }
    else{
        int m;
        char buff2[MAX];
        close(fds[1]);
        while((m=read(fds[0],buff2,MAX))){
            int j;
            int cmp=0;
            char tmp[m];
            for(j=0;j<m;j++){
                if(j>0){
                    if(tmp[cmp]!=buff2[j]){
                        cmp++;
                        tmp[cmp]=buff2[j];
                    }
                }
                else{
                    tmp[j]=buff2[j];
                }
            }
            write(1,tmp,cmp+1);
        }
    }