On Wed, 1 Mar 2000, Balazs Scheidler wrote:

ops, this is a docbug. earlier syslog-ng was able to do this, but this maxed out CPU usage. It is not possible to decide whether new data arrived to a file using poll()

I do a tail-like operation and sleep a predetermined interval between fgets. If you set the pause high-enough, it doesn't take much CPU (but then, the logfile is processed on bursts, and not so smoothly). char *fileName = "/var/log/syslogfile"; FILE *fileDescriptor; char *ptr; char buffer[510]; /* sleep 30 seconds between log-file reads */ int sleepLength = 30; /* 20 consecutive reads with no data = frozen log file */ int maxReads = 36; int EOFile = 0; /* not yet at the end of the log file */ int whatever_procedure (void) { if ((fileDescriptor = fopen (fileName, "r")) == (FILE *) NULL) { fprintf (stderr, "Couldn't open logfile: %s\n", fileName); return (0); } /* if EOFile == 0, we're not at the end of the log file */ /* if EOFile == 1, we're at the end of the file, and read good data */ /* if EOFile > 1, it is the number of reads with no new data */ for (;;) { while (fgets (buffer, sizeof (buffer), fileDescriptor) != (char *) NULL) { /* skip ahead to the end of the logfile */ if (EOFile != 0) { /* now we're tailing the end of the logfile */ EOFile = 1; /* Now do whatever you want with the buffer[] that was read from the logfile */ } } EOFile++; if (EOFile > maxReads) /* too many reads with no data, try reopening logfile */ { fclose(fileDescriptor); if ((fileDescriptor = fopen (fileName, "r")) == (FILE *) NULL) { fprintf (stderr, "Couldn't open log file: %s\n", fileName); return (0); } EOFile = 0; } sleep (sleepLength); } }