I wish to write a graphical tool with which one could configure and query information about a Linux system.
In order to achieve some independence from the underlying Linux distribution, I am planning to require that the target system uses systemd, and that the target system has the PackageKit console program installed.
With this, I will have excluded Slackware Linux, since it does not use systemd.
What other considerations should I have in mind when designing such a tool? With the use of an abstraction layer away from the package manager, and with the use of systemd, are there any other things that I would have to consider?
Related
I am curious about mechanism of Linux compatibility layer of FreeBSD and got some info below.
https://en.wikipedia.org/wiki/FreeBSD#Compatibility_layers_with_other_operating_systems
https://unix.stackexchange.com/questions/172038/what-allows-bsd-to-run-linux-binaries-but-not-vice-versa
The key difference between two OSes is difference of system calls.
And, I know Linux app and BSD app depend on different standard dynamic libraries (linux-gate.so.1 for example).
Is there anything else in the implementation?
The approach to being able to run Linux apps in FreeBSD is multi-faceted.
The parts of the strategy, as I understand it, are as follows:
Provide a system call layer that mimics as close as it can the Linux system call structure and semantics. In FreeBSD, this layer is called 'the linuxolator'
Install a set of vanilla pre-compiled Linux userland libraries. These libraries work because the linuxolator provides the right system calls that they depend on.
Install/provide/mount platform services that Linux userland libraries and apps expect. For example:
Mount a Linux-compatible procfs - linprocfs.
Install pre-compiled Linux apps and have them depend on these Linux userland libraries.
The Linux Apps call the Linux libraries which call the Linuxolator's Linux system calls which call the FreeBSD system calls.
Some functionality is available on Linux (udev, systemd, inotify(7), ...) but not on FreeBSD (and probably vice versa).
Some system calls have different flags. FreeBSD mmap(2) is not exactly the same as Linux mmap(2), etc...
Both are Unix systems, but the devil is in the details.
If you want to code in C an application for both OSes, try hard to follow POSIX.
I know Rust can handle windows and *nix filesystems. I saw there is support to fork processes - is this also cross-platform? Would I be able to write a *nix daemon and a Windows service with the same codebase?
There is no such thing as fork on Windows (it uses CreateProcess instead).
More generally, Unix daemons and Windows services are very different (the latter has to comply with specific Windows interfaces), so you would need a significant abstraction layer if you want to share some code base. As far as I can tell, there is no library providing such an abstraction layer yet.
I am looking for design suggestions/documents etc. which contains specifics of system applications management in Linux (Ubuntu, Debian etc.)
Can you please point to a source of information or suggest a design?
I'm not sure to understand what you mean by system applications management (certainly it can mean several different things).
In practice, Linux distributions have some package management system to deal with that issue. init or systemd (etc....) is in charge of starting/stopping/managing daemons and servers. Its configuration is related to packaging.
Read also Ubuntu Packaging Guide and How To Package For Debian and Debian new Maintainer guide etc...
If you are coding some service application, read Advanced Linux Programming and about daemon(3) & syslog(3)
Also, study the source code of relevant system applications (similar to the one you are dreaming of), since Linux is generally (mostly) free software.
I am planning to implement Hiawatha web server on a non-linux platform which is uC/OS-II RTOS.
I need help to port the Linux dependent API's to RTOS platform.
Kindly let me if there are already build libraries that I can use to port Linux on RTOS.
Thanks in Advance
Any code that uses more than just the standard C library will require some porting effort - the extent to which non-standard and OS specific libraries and calls are made will determine the effort required or even the feasibility of such a port.
Most Linux code of any complexity will require a POSIX API and networking code will probably use BSD sockets. Multi-threaded code would likley use pthreads. uC/OS-II has neither of these; it deals with only scheduling, timing, synchronisation and inter-process communication; it is a scheduling kernel, not a full OS in the same sense as Linux - it does not even have a file system - a requirement of most Linux code. Of course adding additional libraries and extensions may provide some or all of what you may need.
Moreover uC/OS-II's simple one-thread-per-priority-level scheduler would make typical Linux multi-threaded code hard to schedule in the manner intended. Most RTOSes (including uC/OS-III) support round-robin/time-sliced scheduling of tasks at the same priority level, but uC/OS-II does not; possibly making it unsuitable for this task.
Something more sophisticated that uC/OS-II may be in order, or perhaps using code more suited to uC/OS-II perhaps. eCos for example is a far more complete RTOS for embedded systems; it is open-source and includes a POSIX API, file-system support and a socket API. It would be far easier to port Linux code to that. Equally there are many lightweight embedded webserver examples that are probably more suited to uC/OS-II and other simple RTOS or even no OS at all. LwIP for example is a TCP/IP stack for small embedded systems for which uC/OS-II ports exist and for which there are web server examples.
The point is that Linux are uC/OS-II are not comparable; one requires < 10Kb of code, the other has a minimal foot-print of about 4Mb! To get Linux code to run on such a system will require you to add a lot of additional code to provide the missing services, and it may not be feasible on your target platform.
[Edit: 08 July 2012]
Have you considered using Micrium's own TCP/IP stack and μC/HTTPs web-server add-on? It is likley to be better integrated to uC/OS-II and provide better performance than non-RTOS specific third-party code.
I have to check installation steps of my application on different production machines. I want to check how can I install my application on HP UX. I have only linux/windows machines but dont have real physical HP unix machine. Is there any way i can check installation steps of HP unix. I am thinking of any virtual environment or any flavour that run on linux or windows which gives accessiblity and functionality of HP unix.
I am looking something to cross check platfrom installation steps.
The short answer is no. HP-UX is as different from Linux as Linux is from Windows (almost). There would be many differences in libraries, patches, installed utilities, build tools, etc.
A few examples:
HP-UX does not come pre-installed with the bash shell
HP-UX uses a proprietary software packager and installer called swinstall (analogous to RPM but completely different)
Partition layout is different
Many common utilities behave differently. "echo" is one of many examples. This will affect things if your build process uses shell utilities
Even if you can test the install, don't you need to test the product's operation on HP-UX?
Not saying it's impossible. If your application uses basic, nonspecific utilities for install, it might work. There is no way to know without a running installation. Unfortunately you need Itanium hardware and the O/S.
My recommendation would be to get your application working on Solaris and any other Unixes first. The more platforms you test on, the more portable your code will become on all of them. Then, put out some feelers and find someone with a system you can borrow time on.
Worst case, find an Itanium server like an rx2620 on eBay, should not cost too much. Even better if the seller forgets to wipe the O/S :). You'll need a terminal and possibly null modem. 11.31 (11iv3) is the latest version of the O/S.