You seem to be getting some parts of dmesg in messages, but not your 'hello', possibly because it's just an 'alert' and not anything critical. the system logger is able to tell the different levels of criticality apart.
But KERN_ALERT is on a higher, 2nd, log-level than is KERN_CRIT!
Snippet from kernel.h:
Code:
#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 */
Hi Friends,
Can any of you explain me about the below line of code?
mn_code=`env|grep "..mn"|awk -F"=" '{print $2}'`
Im not able to understand, what exactly it is doing :confused:
Any help would be useful for me.
Lokesha (4 Replies)
Doubt regarding using "exec" command to redirect the STDERR to a file. e.g I did it this way.
mystage.sh
#!/bin/sh exec 2>stage.err
....
....
cat stage.err
mv: cannot move `/root/stage' to a subdirectory of itself, `/root/stage_old/stage'
ls: *.zDB: No such file or... (0 Replies)
Hi,
I am having an issue with using sockets.
I have a program which binds to a socket and listen on it. Later I spawn a thread to handle some function. In the new thread created I need to call a shell script which executes the specified function. Here I am using a system command to call the... (5 Replies)
Hello ;
This what i want to do :
I know that in the system call
#include <sys/socket.h>
int bind(int socket, const struct sockaddr *address,
socklen_t address_len);
you can specify the local port for your socket, but im using a private library , and im sure that in that library... (0 Replies)
Hi,
I have line in input file as below:
3G_CENTRAL;INDONESIA_(M)_TELKOMSEL;SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL
My expected output for line in the file must be :
"1-Radon1-cMOC_deg"|"LDIndex"|"3G_CENTRAL|INDONESIA_(M)_TELKOMSEL"|LAST|"SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL"
Can someone... (7 Replies)
Discussion started by: shis100
7 Replies
6. Post Here to Contact Site Administrators and Moderators
Majority of the questions are pertaining file/string parsing w.r.t
sed
or
awk
It would be nice to have these two as their own sub category under shell-programming-scripting which can avoid lot of duplicate posts. (1 Reply)
How to use "mailx" command to do e-mail reading the input file containing email address, where column 1 has name and column 2 containing “To” e-mail address
and column 3 contains “cc” e-mail address to include with same email.
Sample input file, email.txt
Below is an sample code where... (2 Replies)
Hello experts!
I need your help please
I have a file.txt of which I want to extract 3rd and 4th columns with date with the form e.g.:
2016-11-25 03:14:50and pass them to "date" command, but also append the 9th column in a file as well.
So I want to execute
date -d '2016-11-25 03:14:50' ... (2 Replies)
Hello.
System : opensuse leap 42.3
I have a bash script that build a text file.
I would like the last command doing :
print_cmd -o page-left=43 -o page-right=22 -o page-top=28 -o page-bottom=43 -o font=LatinModernMono12:regular:9 some_file.txt
where :
print_cmd ::= some printing... (1 Reply)
Cannot present unpresented disks back again. On a test server tried this as a solution "multipath -r" and it worked. Too worried to try it in production before I know all the information.
Any info would be appreciated!
Also some links to the documentation on this specific issue could help a... (1 Reply)
Discussion started by: jsteppe
1 Replies
LEARN ABOUT REDHAT
klogctl
SYSLOG(2) Linux Programmer's Manual SYSLOG(2)NAME
syslog, klogctl - read and/or clear kernel message ring buffer; set console_loglevel
SYNOPSIS
/* The glibc interface */
#include <sys/klog.h>
int klogctl(int type, char *bufp, int len);
/* The handcrafted system call */
#include <unistd.h>
#include <linux/unistd.h>
_syscall3(int, syslog, int, type, char *, bufp, int, len);
int syslog(int type, char *bufp, int len);
DESCRIPTION
If you need the libc function syslog(), (that talks to syslogd(8)), then look at syslog(3). The system call of this name is about control-
ling the kernel printk() buffer, and the glibc version is called klogctl().
The type argument determines the action taken by this function.
Quoting from kernel/printk.c:
/*
* Commands to sys_syslog:
*
* 0 -- Close the log. Currently a NOP.
* 1 -- Open the log. Currently a NOP.
* 2 -- Read from the log.
* 3 -- Read up to the last 4k of messages in the ring buffer.
* 4 -- Read and clear last 4k of messages in the ring buffer
* 5 -- Clear ring buffer.
* 6 -- Disable printk's to console
* 7 -- Enable printk's to console
* 8 -- Set level of messages printed to console
*/
Only function 3 is allowed to non-root processes.
The kernel log buffer
The kernel has a cyclic buffer of length LOG_BUF_LEN (4096, since 1.3.54: 8192, since 2.1.113: 16384) in which messages given as argument
to the kernel function printk() are stored (regardless of their loglevel).
The call syslog (2,buf,len) waits until this kernel log buffer is nonempty, and then reads at most len bytes into the buffer buf. It
returns the number of bytes read. Bytes read from the log disappear from the log buffer: the information can only be read once. This is
the function executed by the kernel when a user program reads /proc/kmsg.
The call syslog (3,buf,len) will read the last len bytes from the log buffer (nondestructively), but will not read more than was written
into the buffer since the last `clear ring buffer' command (which does not clear the buffer at all). It returns the number of bytes read.
The call syslog (4,buf,len) does precisely the same, but also executes the `clear ring buffer' command.
The call syslog (5,dummy,idummy) only executes the `clear ring buffer' command.
The loglevel
The kernel routine printk() will only print a message on the console, if it has a loglevel less than the value of the variable con-
sole_loglevel (initially DEFAULT_CONSOLE_LOGLEVEL (7), but set to 10 if the kernel commandline contains the word `debug', and to 15 in case
of a kernel fault - the 10 and 15 are just silly, and equivalent to 8). This variable is set (to a value in the range 1-8) by the call
syslog (8,dummy,value). The calls syslog (type,dummy,idummy) with type equal to 6 or 7, set it to 1 (kernel panics only) or 7 (all except
debugging messages), respectively.
Every text line in a message has its own loglevel. This level is DEFAULT_MESSAGE_LOGLEVEL - 1 (6) unless the line starts with <d> where d
is a digit in the range 1-7, in which case the level is d. The conventional meaning of the loglevel is defined in <linux/kernel.h> as fol-
lows:
#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 */
RETURN VALUE
In case of error, -1 is returned, and errno is set. Otherwise, for type equal to 2, 3 or 4, syslog() returns the number of bytes read, and
otherwise 0.
ERRORS
EPERM An attempt was made to change console_loglevel or clear the kernel message ring buffer by a process without root permissions.
EINVAL Bad parameters.
ERESTARTSYS
System call was interrupted by a signal - nothing was read. (This can be seen only during a trace.)
CONFORMING TO
This system call is Linux specific and should not be used in programs intended to be portable.
NOTES
From the very start people noted that it is unfortunate that kernel call and library routine of the same name are entirely different ani-
mals. In libc4 and libc5 the number of this call was defined by SYS_klog. In glibc 2.0 the syscall is baptised klogctl.
SEE ALSO syslog(3)Linux 1.2.9 2001-11-25 SYSLOG(2)