* Re: should man page for syslog(2) be updated WRT log levels?
2014-05-26 13:06 should man page for syslog(2) be updated WRT log levels? Robert P. J. Day
@ 2014-06-15 18:17 ` Michael Kerrisk (man-pages)
0 siblings, 0 replies; 2+ messages in thread
From: Michael Kerrisk (man-pages) @ 2014-06-15 18:17 UTC (permalink / raw)
To: Robert P. J. Day
Cc: mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w,
linux-man-u79uwXL29TY76Z2rM5mHXA
Hi Robert,
On 05/26/2014 03:06 PM, Robert P. J. Day wrote:
>
> hi, not sure if this question makes any sense but, currently, the
> man page for syslog(2) claims:
>
> The conventional meaning of the loglevel is defined in
> .I <linux/kernel.h>
> as follows:
>
> .nf
> #define KERN_EMERG "<0>" /* system is unusable */
> #define KERN_ALERT "<1>" /* action must be taken immediately */
> #define KERN_CRIT "<2>" /* critical conditions */
> #define KERN_ERR "<3>" /* error conditions */
> #define KERN_WARNING "<4>" /* warning conditions */
> #define KERN_NOTICE "<5>" /* normal but significant condition */
> #define KERN_INFO "<6>" /* informational */
> #define KERN_DEBUG "<7>" /* debug-level messages */
>
> first, those defines don't seem to exist anymore --
Yup. there was a change with kernel commit
04d2c8c83d0e3ac5f78aeede51babb3236200112, it seems.
> in userspace, one
> finds definitions in <sys/syslog.h>:
>
> #define LOG_EMERG 0 /* system is unusable */
> #define LOG_ALERT 1 /* action must be taken immediately */
> #define LOG_CRIT 2 /* critical conditions */
> #define LOG_ERR 3 /* error conditions */
> #define LOG_WARNING 4 /* warning conditions */
> #define LOG_NOTICE 5 /* normal but significant condition */
> #define LOG_INFO 6 /* informational */
> #define LOG_DEBUG 7 /* debug-level messages */
Those defines are there for syslog(3).
> also, in kernelspace, there is the newer header file kern_levels.h
> which defines log levels differently these days:
>
> #define KERN_SOH "\001" /* ASCII Start Of Header */
> #define KERN_SOH_ASCII '\001'
>
> #define KERN_EMERG KERN_SOH "0" /* system is unusable */
> #define KERN_ALERT KERN_SOH "1" /* action must be taken immediately */
> #define KERN_CRIT KERN_SOH "2" /* critical conditions */
> #define KERN_ERR KERN_SOH "3" /* error conditions */
> #define KERN_WARNING KERN_SOH "4" /* warning conditions */
> #define KERN_NOTICE KERN_SOH "5" /* normal but significant condition */
> #define KERN_INFO KERN_SOH "6" /* informational */
> #define KERN_DEBUG KERN_SOH "7" /* debug-level messages */
>
> #define KERN_DEFAULT KERN_SOH "d" /* the default kernel loglevel */
>
> i have no idea how any of that should affect the man page for
> syslog(2), and possibly others. thoughts? or am i just totally
> misunderstanding something?
So, some details have changed, and I agree that the page could be clearer.
But, in the meantime, I'll apply a patch something like the below.
Cheers,
Michael
diff --git a/man2/syslog.2 b/man2/syslog.2
index 5053b88..10894bf 100644
--- a/man2/syslog.2
+++ b/man2/syslog.2
@@ -1,3 +1,4 @@
+'\" t
.\" Copyright (C) 1995 Andries Brouwer (aeb-rh8NL+sEX9E@public.gmane.org)
.\"
.\" %%%LICENSE_START(VERBATIM)
@@ -232,20 +233,21 @@ This level is
(6) unless the line starts with <d>
where \fId\fP is a digit in the range 1-7, in which case the level
is \fId\fP.
-The conventional meaning of the loglevel is defined in
-.I <linux/kernel.h>
-as follows:
+The conventional meaning of the loglevel is as follows:
-.nf
-#define KERN_EMERG "<0>" /* system is unusable */
-#define KERN_ALERT "<1>" /* action must be taken immediately */
-#define KERN_CRIT "<2>" /* critical conditions */
-#define KERN_ERR "<3>" /* error conditions */
-#define KERN_WARNING "<4>" /* warning conditions */
-#define KERN_NOTICE "<5>" /* normal but significant condition */
-#define KERN_INFO "<6>" /* informational */
-#define KERN_DEBUG "<7>" /* debug-level messages */
-.fi
+.TS
+lB lB lB
+lB c l.
+Kernel constant Level value Meaning
+KERN_EMERG 0 System is unusable
+KERN_ALERT 1 Action must be taken immediately
+KERN_CRIT 2 Critical conditions
+KERN_ERR 3 Error conditions
+KERN_WARNING 4 Warning conditions
+KERN_NOTICE 5 Normal but significant condition
+KERN_INFO 6 Informational
+KERN_DEBUG 7 Debug-level messages
+.TE
.SH RETURN VALUE
For \fItype\fP equal to 2, 3, or 4, a successful call to
.BR syslog ()
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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