I have this sample code: First run: Well I think this is all expected as p is 1 byte long character defined in ASCII and I am reading 3 bytes. (2 p’s and Line break) In the terminal, again I see 2 characters. Now let’s try with a character that is 2 bytes long: What I do not understand is,
Tag: c++
Rewrite at the beginning of the file
I was trying to rewriting text at beginning of file but facing the following: The header file is test.h: The source file is test.c : The main file is main.c: The make file is: The out put was expected is: But it is replacing first few characters of the first line. Where I am going wrong? Answer The output is
escape alarm() process timeout with nohup or setsid?
I have a monitoring application, Zabbix agent, that allows me to run arbitrary commands/scripts and grab the return value. The agent is configured with a timeout and any command that exceeds the timeout will be killed. For every command that is run, it first sets the timeout via alarm(timeout) and then forks …
Boosts JSON parser escapes quotation marks on MacOS but not on Linux
I have a C++ program running on a server returning JSON formatted data, serialized with boost. In some cases one value part of a JSON packet is another JSON packet serialized to string. Running in XCode on my developing machine the program returns me the value data with escaped quotation marks, compiled on th…
Host testing C program with hard coded memory addresses
We will write functional/unit tests for C code. This C program will be run as embedded software. However we need to run tests on a Linux environment. The problem is that parts of the code under test looks like this: my_addresses.h: my_code.c Obviously, this will not run so well on Linux host environment. Is t…
Can-Bus Communication – MSG-Structure (WinUser.h) Linux equivalent
Hello StackOverflow Community I’ve searched for quite a while now but I don’t find a solution for my problem. I’m working on a project right now, where I have to port a Windows tool on to a Linux operating system (Ubuntu 12.04LTS to be specific). The Windows-based tool is written in C++ and …
Sending an arrow key with fprintf
I’m testing out pipes and have hit a little road block. I want to be able to simulate pressing the right arrow key through a file pointer opened by popen. The file pointer opens a display program on a different terminal, much like a projector. I would like to send a signal to advance the next image (the…
Why doesn’t Linux prevent spawning infinite number of processes and crashing?
With the very simple code below, my system (Ubuntu Linux 14.04) simply crashes not even letting my mouse respond. I had to force quit with the power button. I thought Linux is a stable OS tolerable of handling such basic program errors. Did I miss something? Answer Congratulations, you’ve discovered the…
gcc segmentation fault – how can I find a line where it happened?
I’m using Ubuntu and gcc. My application crashes I only have Segmentation fault message in console. (previously Segmentation fault (core dumped) was reported but now it changed to just Segmentation fault). There are no hints where the problem is so I do not understand how should I fix the problem. I nee…
How does read(2) in Linux C work?
According to the man page, we can specify the amount of bytes we want to read from a file descriptor. But in the read’s implementation, how many read requests will be created to perform a read? For example, if I want to read 4MB, will it create only one request for 4MB or will it split it into multiple …