Fix: update lttng.1 man page

[lttng-tools.git] / doc / man / lttng.1

diff --git a/doc/man/lttng.1 b/doc/man/lttng.1
index afa8eb85371b40c55d2d0aa175b3976a853c985e..283367190a30e010805db1cb3d8d971931ff794c 100644 (file)
--- a/doc/man/lttng.1
+++ b/doc/man/lttng.1
@@ -1,7 +1,7 @@
 .TH "LTTNG" "1" "December 3rd, 2012" "" ""
 
 .SH "NAME"
-lttng \(em LTTng 2.1.x tracer control command line tool
+lttng \(em LTTng 2.x tracer control command line tool
 
 .SH "SYNOPSIS"
 
@@ -101,8 +101,9 @@ data output:
 Please take a look at the help (\-h/\-\-help) for a detailed list of available
 contexts.
 
-If no channel is given (\-c), the context is added to all channels. Otherwise
-the context will be added only to the given channel (\-c).
+If no channel is given (\-c), the context is added to all channels that were
+already enabled. If the session has no channel, a default channel is created.
+Otherwise the context will be added only to the given channel (\-c).
 
 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
 file.
@@ -214,6 +215,10 @@ automatically created having this form: 'auto-yyyymmdd-hhmmss'.
 
 If no \fB\-o, \-\-output\fP is specified, the traces will be written in
 $HOME/lttng-traces.
+
+The $HOME environment variable can be overridden by defining the environment
+variable LTTNG_HOME. This is useful when the user running the commands has
+a non-writeable home directory.
 .fi
 
 .B OPTIONS:
@@ -304,8 +309,11 @@ If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngr
 file.
 
 It is important to note that if a certain type of buffers is used, the session
-will be set with that type and all other subsequent channel need to have the
+will be set with that type and all other subsequent channel needs to have the
 same type.
+
+For the kernel tracer (\-k), once the session is started at least once, it's
+not possible anymore to enable new channel for that session.
 .fi
 
 .B OPTIONS:
@@ -330,6 +338,10 @@ same type.
         Subbuffer size in bytes {+k,+M,+G}
         (default UST uid: 131072, UST pid: 4096, kernel: 262144, metadata: 4096)
         Rounded up to the next power of 2.
+
+        The minimum subbuffer size, for each tracer, is the max value between
+        the default above and the system page size. You can issue this command
+        to get the current page size on your system: \fB$ getconf PAGE_SIZE\fP
 \-\-num-subbuf NUM
         Number of subbuffers. (default UST uid: 4, UST pid: 4, kernel: 4, metadata: 2)
         Rounded up to the next power of 2.