How the GRUB2 found a place of the erubenv file - ubuntu-18.04

I working on some programing project, and at the time i looking for an information about of : how the GRUB2 using the file /boot/grub/grubenv ?
In particulary how the GRUB find the start LBA of the file before loading content of it ?
TIA.

GRUB use file system drivers to performs working on partition as usual.

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Can Logrotate be use in C?

I'm a newbie on linux and I was planning to use logrotate so that my log files which generate inside a radio file system, would not getting larger size and cause any memory issue.
but as can see from below, this configuration is set at logrotate.conf file in linux, then I am confused and wonder is it possible to add this thing as a "coding style" in my C files so that it work on my radio which is running Linux system.
The radio don't have this logrotate thing under /etc/logrotate.d path after all. I also unable to install any logrotate or execute the command "man logroate", it tells : no manual entry for 'logrotate'.
/var/logs/*.log {
hourly
missingok
rotate 24
compress
create
}
Can it be called like normal function such as fclose() or fopen() in .C files?
If it can be used in C files, what is the correct way to configure the parameter?
I think you misinterpreted how logrotate work: It only work with files created by service/application on host machine.
For example on your linux machine you are running mailing server postfix (base on config you posted):
Postfix service filling log file /var/log/postfix.log
Logrotate take every hour postfix.log and create compressed file postfix.1
Increment number of already existing archive files
Logrotate keep 24 compressed files (= 1 day)
In you case you have to setup application logging to save log files and then you can apply logrotate to it.
Logrotate man page can be found here

Build make file arm microcontroller

We bought an ECU emulator made with stm32f103,
The source files are attached to them. But there is no file (BIN or HEX) and there is a make file that needs to be built, but when I tried to create it but it is not possible for me,
If you have experience with this process, thank you for guiding me ...
Best Regard.

uboot using FIT to upgrade filesystem

I want to upgrade my systems in the field using the uboot FIT images.
My system is a custom firmware, booted by uboot. So far the FIT filesystem works very good. It provides a shasum verified upload. I am using uboot scripts to update stuff on the target.
One intriguing type defined in uboot docs is type "filesystem". The actual content could be several things, like maybe tar'ed bunch of files, or an actual collection of separate individual files in one chunk in the FIT.
In another FIT question, Tom Rini implied that a filesystem is really just a binary blob. What goes into it is my problem and that uboot could then just mmc write ... or usb write ... to create the new filesystem on some partition. Is this really the case?
How can I build a filesystem (say FAT), on a host build computer for packaging with FIT?
Thanks, Steve
The creation of a filesystem image will depend on the filesystem itself. In many cases, build systems such as OpenEmbedded or buildroot can help you here as they will create the images for you.

Decompressing .lz file

Curiosity is one of my personal keys. I got a folder of an executable c application, this folder include many files some are files.so , files.ini and other files.lz and I decided to try do some kind of reverse engineering, so I have used a reverse engineering online tool for the files.so and files.ini are already opened via notepad as we all know, but now my problem is about opening files.lz, which i already know that it contains libraries to be used for functions on files.so
This is what i want to know and to have some help in it how can I decompress it via a desktop tool or even an online tool?
Should be Lzip.
When you are in the linux-world, one very usefull commands is file:
$ file myFile.lz
myFile.lz: lzip compressed data, version: 1

Is their any open source project based GRE?

I want to build one network system which can make client communicate thought NAT? any suggestion ?
RFC 1701 can be implemented using ifconfig and route. You don't really need C code AFAIK. I do not know of open source to create what you specified.
The qnx site has an example:
http://www.qnx.com/developers/docs/6.4.0/neutrino/technotes/gre.html
A linux example:
http://tier.cs.berkeley.edu/drupal/howto/ip-tunnel-using-gre-on-linux

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