Document the options in the README

2 files changed, 25 insertions, 5 deletions

diff --git a/README b/README
index a4a200a..b38911e 100644
--- a/README
+++ b/README
@@ -8,9 +8,6 @@ versions of the Linux kernel to speed up tailing files in the follow mode (the
 listens to special events sent by the kernel through the inotify API to
 determine whether a file needs to be reread.
 
-Currently inotail is not fully compatible to neither POSIX or GNU tail but might
-be in the future.
-
 Requirements
 ------------
 - Linux kernel 2.6.13 or higher with CONFIG_INOTIFY enabled
@@ -33,6 +30,29 @@ inotail binary to /usr/ and the manpage to /usr/share/man/ respectively type:
 
 	$ make prefix=/usr install
 
+Compatibility & options
+-----------------------
+inotail is fully option compatible with current POSIX and GNU tail, though the
+obsolescent options present in previous versions of those are not present (e.g.
+inotail +/-<num>). The following options are present in inotail for
+compatibility reasons (e.g. to use inotail as a tail replacement in scripts) but
+do have no effect on inotail besides emiting a warning:
+
+-s N, --sleep-interval=N  inotail does not need a sleep interval because it's
+			  relying on inotify.
+
+--max-unchanged-stats=N   inotail watches the containing directory of the file
+                          when following by name (--follow=name or -F). Thus it
+                          gets notified when a file gets moved or deleted.
+
+--pid=PID                 Watching the writer PID ios not possible, because
+                          inotail blocks on the read() call on the inotify fd.
+			  In the worst case, the dying process wouldn't cause an
+			  inotify event, so inotail would never get back from
+			  the read().
+
+These options are neither documented in the manpage nor the in-program help.
+
 License
 -------
 inotail is licensed under the terms of the GNU General Public License version 2
diff --git a/inotail.c b/inotail.c
index 53101a8..55fa532 100644
--- a/inotail.c
+++ b/inotail.c
@@ -783,7 +783,7 @@ int main(int argc, char **argv)
 		case 's':
 			/* No sleep interval because we're never sleeping.
 			 * That's the whole point of inotail! */
-			fprintf(stderr, "Warning: Option '-s' has no effect in inotail\n");
+			fprintf(stderr, "Warning: Option '-s' has no effect, ignoring\n");
 			break;
 		case PID_OPTION:
 			/* Watching the PID is not possible because of the
@@ -792,7 +792,7 @@ int main(int argc, char **argv)
 			/* inotail (will) watch the containing directory for the
 			 * file being moved or deleted, so there is no need for
 			 * this either */
-			fprintf(stderr, "Warning: Option '--%s' has no effect in inotail\n", long_opts[option_idx].name);
+			fprintf(stderr, "Warning: Option '--%s' has no effect, ignoring\n", long_opts[option_idx].name);
 			break;
 		default:
 			usage(EXIT_FAILURE);