If you are using pmap or using strace and want to covert kernel address to function name then you can use the following technique.
First you need to install elfutils, if not installed.
dnf install elfutils
and after this you can use the following command
eu-addr2line -f -e /boot/vmlinuz-$(uname -r) <addr> #Example eu-addr2line -f -e /boot/vmlinuz-$(uname -r) 00007f36a8045000
With the advent of tools like Docker, Linux Containers, and others, it has become super easy to isolate Linux processes into their own little system environments. This makes it possible to run a whole range of applications on a single real Linux machine and ensure no two of them can interfere with each other, without having to resort to using virtual machines. These tools have been a huge boon to PaaS providers. But what exactly happens under the hood?
Continue readingVery quick hack to fix the font hinting automatically. Just execute the below:
sudo ln -s /usr/share/fontconfig/conf.avail/10-autohint.conf /etc/fonts/conf.d/10-autohint.conf
After this you should see the font hinting enabled and thus better experience with fonts.
In shell scripts if you need to get you local IP address corresponding to your hostname then you can use this command
hostname -i
I was trying to setup a simply webservice to reply to POST requests. Earlier this was being done in tomcat which seem a little overkill to me since I already had a webserver up and running. So, a quick c program to respond to request is all that I needed. And here is the result.
/*
* =====================================================================================
*
* Filename: Login.cpp
*
* Description:
*
* Version: 1.0
* Revision: none
* Compiler: gcc
*
* Author: Amit Agarwal (),
* Organization:
*
* == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == =
*/
#include <stdio .h>
#include <stdlib .h>
#include <string .h>
#define MAXLEN 1024
#ifdef DBG
#define DEBUG(a,b) fprintf(stderr, a, b);
#else
#define DEBUG(a,b)
#endif
#define HEAD "n"
#define TAIL ""
int main(void)
{
char input[MAXLEN];
char * data;
char*lenstr;
long len;
printf("%s%c%cnn",
"Content-Type:text/xml;charset=iso-8859-1", 13, 10);
// len = getenv("QUERY_STRING"); // This is for GET
lenstr = getenv("CONTENT_LENGTH");
DEBUG( "Length string is %sn", lenstr);
if(lenstr == NULL || sscanf(lenstr,"%ld",&len)!=1 || len > MAXLEN)
printf("Error in invocation - wrong FORM probably.");
DEBUG( "Length is %ldn", len);
{
int count=0;
while ( count < len )
input[count++] = getchar();
input[count]='?';
DEBUG ( "Read characters = %dn", count)
}
//fprintf(stderr, "VAlue is %sn", input);
///unencode(input + 5 , input + len, data);
data = input;
DEBUG("Data value is %sn", data);
printf(HEAD);
printf("Everything else goes heren");
printf(TAIL);
fprintf(stderr, "Sent resp: tid[%s], eaid[%s], tcode[%s]n", tid, eaid, tcode);
}
</string></stdlib></stdio>
Additionally, the makefile:
Continue readingfirewalld by default does not allow packets that are dropped. In some cases, you need to find out if some packet is being dropped or not. For doing so you may want to enable logging of dropped packets with the following command:
sudo firewall-cmd --set-log-denied=all
This will enable logging all the packets and help you figure out if firewalld is dropping the packet.
Trying to find the total usage for each of the file types by extension, then here is a quick bash function for you :
disk_usage_type ()
{
find . -name '*'$1 -ls | awk '
BEGIN{
a[0]="Bytes";
a[1]="KB";
a[2]="MB";
a[3]="GB";
}
{sum+=$7; files++;}
END{
print "Total sum is ::\t" sum;
print "Total files ::\t" files;
while (sum > 1024) {
sum=sum/1024;
count++;
};
print sum" "a[count];
}'
}
Just define the function in one of your bash startup files. After that to use the function pass in the extension for which you would like to find the total size. Output should be something like below:
Continue reading