Difference between revisions of "UsingSyslog"

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(New page: ==Calling syslog method from your C source code== This part is quiet simple, but we need to correctly use each parameter. First step is to declare us as syslog client : <source lang="C"> ....)
 
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     ...
 
     ...
 
</source>
 
</source>
if you compile the source file:
+
If you compile the source file:
 
<source lang="C">
 
<source lang="C">
 
// log_syslog.c
 
// log_syslog.c
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int main(int argc, char *argv[])
 
int main(int argc, char *argv[])
 
{
 
{
openlog("program_name", LOG_PID, LOG_USER);
+
    openlog("program_name", LOG_PID, LOG_USER);
syslog(LOG_INFO, "%s called with %d arguments", argv[0], argc - 1);
+
    syslog(LOG_INFO, "%s called with %d arguments", argv[0], argc - 1);
closelog();
+
    closelog();
 
+
    return 0;
return 0;
+
 
}
 
}
 
</source>
 
</source>
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itsme@mycomputer:~/log_syslog$ ./log_syslog pim pam poum
 
itsme@mycomputer:~/log_syslog$ ./log_syslog pim pam poum
 
</pre>
 
</pre>
You will probably obtain no result in shell, but you can take a look in you're system log (/var/log/syslog or /var/log/messages)
+
You will probably obtain no result in shell, but you can take a look in your system log (/var/log/syslog or /var/log/messages)
 
<pre class="apf">
 
<pre class="apf">
 
itsme@mycomputer:~/log_syslog$ tail -n 2 /var/log/syslog
 
itsme@mycomputer:~/log_syslog$ tail -n 2 /var/log/syslog

Revision as of 17:53, 19 September 2012

Calling syslog method from your C source code

This part is quiet simple, but we need to correctly use each parameter. First step is to declare us as syslog client :

...
#include <syslog.h>

int main(int argc, char *argv[])
{
    ...
    openlog("program_name", LOG_PID, LOG_USER);
    ...
    closelog();
    ...
}

Then, you can call syslog from your code using printf like format :

    ...
    syslog(LOG_INFO, "%s called with %d arguments\n", argv[0], argc);
    ...

If you compile the source file:

// log_syslog.c
#include <syslog.h>

int main(int argc, char *argv[])
{
    openlog("program_name", LOG_PID, LOG_USER);
    syslog(LOG_INFO, "%s called with %d arguments", argv[0], argc - 1);
    closelog();
    return 0;
}

With the command :

itsme@mycomputer:~/log_syslog$ gcc log_syslog.c -o log-syslog

Then run it 2 times :

itsme@mycomputer:~/log_syslog$ ./log_syslog
itsme@mycomputer:~/log_syslog$ ./log_syslog pim pam poum

You will probably obtain no result in shell, but you can take a look in your system log (/var/log/syslog or /var/log/messages)

itsme@mycomputer:~/log_syslog$ tail -n 2 /var/log/syslog
Sep 19 18:46:49 mycomputer program_name[3022]: ./log_syslog called with 0 arguments
Sep 19 18:46:53 mycomputer program_name[3023]: ./log_syslog called with 3 arguments

We can notice, that the lines contain program_name[PID] pattern showing us the name we have specified in openlog and the pid of the process because we ask it with LOG_PID argument.