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@xxxxxxxxx>
---
login-utils/utmpdump.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/login-utils/utmpdump.c b/login-utils/utmpdump.c
index 5ccae8655..b9a92b5f6 100644
--- a/login-utils/utmpdump.c
+++ b/login-utils/utmpdump.c
@@ -367,6 +367,10 @@ int main(int argc, char **argv)
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");
--
2.24.3 (Apple Git-128)
