The following usages of utmpdump result in no output being flushed to the specified file because the default output buffering is fully buffered:
$ utmpdump --follow --output myOutputFile /var/log/utmp
$ utmpdump --follow /var/log/utmp > myOutputFile
This change configures line buffering for these scenarios so that output will be flushed after each log event.
Signed-off-by: Andrew Shapiro <anshapiro@gmail.com>
if (!out)
out = stdout;
+ if (follow && (out != stdout || !isatty(STDOUT_FILENO))) {
+ setvbuf(out, NULL, _IOLBF, 0);
+ }
+
if (optind < argc) {
filename = argv[optind];
in = fopen(filename, "r");