Thread: Append a temp file to a log file

hello, i am faced with another problem that I am not sure how to tackle:

Code:

FILE *file = tmpfile();
FILE *logfile;

Code:

time_t time;
fprintf(file, "%s", ctime(&time));

Code:

logfile = fopen("logfile.txt","a");
////////////////
Append here
///////////////////////

Code:

fclose(file);
fclose(logfile);

These are little snippets of my code for my basic direction. Here I am printing the time with some commands entered in to a temp file. After the session is complete I will append the temp file to a log file. Any good way to append the temp to logfile?

You've got the right idea opening the log file for append and the tmp file for read...

Now you can use fread() and fwrite() to transfer the file in chunks.

Close both when you're done.

Originally Posted by CommonTater

You've got the right idea opening the log file for append and the tmp file for read...

Now you can use fread() and fwrite() to transfer the file in chunks.

Close both when you're done.

From the looks of these functions it does not look like text, uses binary?

Here is what I tried and i could open the logfile.txt

Code:

FILE *file = tmpfile();
FILE *logfile;

Code:

int buffer = 256; 
logfile = fopen("logfile.txt","a");
fread(&buffer,sizeof(buffer),1,file);  
fwrite(&buffer,sizeof(buffer),1,logfile);

Code:

fclose(file);
fclose(logfile);

Ok, you're opening the logfile... now you need to open the tmp file for read (same process...)

To read and write you need a character buffer to hold the data, you can't point it at an integer.

Code:

char buffer[256];   // to hold data
int ChrRead;      // to hold data counts

// open and check the logfile
logfile = fopen("logfile.txt","a");  
if (logfile == 0)
  { puts("Error opening logfile\n");
     exit(1); }

// open temp file here

//  transfer the data
do
 { ChrRead = fread(buffer,sizeof(char),sizeof(buffer),file);  
     fwrite(buffer,1,ChrRead,logfile); }
while (ChrRead > 0);

// close files here

Ok, you're opening the logfile... now you need to open the tmp file for read (same process...)

Not sure what you mean but I have opened a temp file and have put some data in it. I never closed it till the end.

Originally Posted by Randellk02

Not sure what you mean but I have opened a temp file and have put some data in it. I never closed it till the end.

Your posted code doesn't show that. Pleas post an update of your complete code, lets see where we're at...

Originally Posted by CommonTater

Your posted code doesn't show that. Pleas post an update of your complete code, lets see where we're at...

This is my main code where i where i am doing the appending.

Code:

  FILE *file = tmpfile();
  FILE *logfile;
  pid_t pid;
  int pd[2];
  pipe(pd);
  pid = fork();
  if(pid == -1){
    fprintf(stderr, "Pipe Error");
    exit(1);
  }
  // printf("1\n");
    if(pid != 0){ // Parent Process writes
        printf("In Parent\n");

      	while (fgets(input, sizeof(input), stdin)) {
            printf("Parent received: %s", input);
            strcpy(in,input); // saves previous command in
   	    strcpy(in2,input); // saves full command in2
            start = append(start, input);
            stripcrlf(input);
            parse(input);
            printf("\n$ ");

            if(strcmp(input,"history") == 0)
     	        displayRecentCommands(start);
            if(input[0] == '!')
                getCommand(start, input, in);

            time_t time;
	    fprintf(file, "%s", ctime(&time));

	    write(pd[1],input, sizeof(input));
            printf("parent end\n");
      	}
    }
    else		// Child Process
    { 
      	read(pd[0],temp,sizeof(temp));
      	while(strcmp(temp,"stop") != 0){		// 4 is ctrl+d ascii
 	   printf("Im in the Child");
           printf("Input Received: %s\n", temp);
           read(pd[0],temp,sizeof(temp));

           int i = 1;
    	   fprintf(file, "%d. Command: %s", i++, temp);
     	}
     
      // exec only returns if error
      //fprintf(stderr, "an error with exec occured.");
      // exit(1);
      printf("child end\n");
    }    
    char buffer[100];
    int Char;
    write(pd[1],"stop", sizeof("stop"));    // send "stop" to end child process 
  
    logfile = fopen("logfile.txt","a");
    Char = fread(buffer,sizeof(char),sizeof(buffer),file);
    while(Char > 0){ 
    	fwrite(buffer,1,Char,logfile);
        Char = fread(buffer,sizeof(char),sizeof(buffer),file);
    }
    fclose(file);
    fclose(logfile);

    savedata(start);
    displaydata(start);
    freedata(start);
    
    return 0;
}

Ok... is it working? What problems are you having?

I don't think it needs to be as complex as it is... certainly I see no need of parent and child processes.

The only comment I have is with the use of Char as a variable name... I'd suggest you pick something a) more descriptive and b) not like a type or function name... Perhaps CharsRead or such...

Originally Posted by CommonTater

Ok... is it working? What problems are you having?

I don't think it needs to be as complex as it is... certainly I see no need of parent and child processes.

The only comment I have is with the use of Char as a variable name... I'd suggest you pick something a) more descriptive and b) not like a type or function name... Perhaps CharsRead or such...

The problem now is when I open my logfile nothing is in it. I use the child process to save the commands to a temp file and the parent executes the command. My code is also running twice so im guessing I need to kill the child right after the parent/child code?

When this started you just wanted to tack a temp file onto the end of a log file. Now it's a lot more complex and I don't think I quite understand what you're up to...

Perhaps one of the others can assist you better.