For some reason, adding n to printf() changes the behaviour of below code. The code without n prints (null) whereas the code with n leads to Segmentation fault. Printf.c Printf.c – Output Printf_Newline.c Printf_Newline.c – Output I am curious to understand the reason behind this. Answer Both are …
pipe command make standard input broken
I have two processes: t1.cpp and t2.cpp. t1.cpp and t2.cpp are simplified ,I want to describe the problem easily. After compiling t1.cpp and t2.cpp. I execute them in this way ./t1 | ./t2. Problems occur! cin >> x; in t2.cpp failed! I have no chance to type from the keyboard. It seems the pipe command i…
electron – incremental updating?
I am using electron-vue & electron-packager. I am wondering whether I can do something like incremental updating, that is, after running an electron build command, I don’t need to copy the whole electron-linux-x64 folder to my dist machine to update it to the newest, but instead I only need to copy …
Java web application seems to go idle quickly in Tomcat
I’m new to java and tomcat. I’m developing a website in java using spring mvc. It’s deployed to a linux server that’s running Tomcat 8. Everything works fine when I deploy, it connects to the database great. The issue is that the site seems to go idle very quickly. I haven’t been…
In the kernel space, how does one get the physical addresses corresponding to a file on ext4-formatted disk
If you’re here: https://github.com/torvalds/linux/blob/master/fs/ext4/file.c#L360 You have access to these two structs inside the ext4_file_mmap function: I am changing the implementation of this function for dax mode so that the page tables get entirely filled out for the file the moment you call mmap …
‘top’ shows Java program using more memory than Java profiler shows
What are the possible causes for when the Linux top command shows a Java process is using 14GBs of memory while Java profiling shows only 2GBs being used? Answer That means that your JVM / Java application is using off-heap memory. Lots of it. It could be memory-mapped files. It could be native libraries: unl…
Why doesn’t grep -lv work?
I want to print out the name of a file if and only if it does not contain the string foo. However, if file contains foo and I run this file is outputted. Why does this happen and what can I do to work around it? Answer -v means to match any line that doesn’t match the pattern. So -lv
Azure Powershell Module – Linux (.NET Core) Support
There exists an AzureRM module that is built on .NET Core. However, the AzureRM module doesn’t have all of the required functionality to interact with Azure. Many of the other cmdlets, such as New-AzureAffinityGroup, are present in the Azure module. Here are a list of other cmdlets: https://www.powershe…
Set docker image username at container creation time?
I have an OpenSuse 42.3 docker image that I’ve configured to run a code. The image has a single user(other than root) called “myuser” that I create during the initial Image generation via the Dockerfile. I have three script files that generate a container from the image based on what operati…
OpenSSL will not release file handles
I am writing a service (in C for CentOS) that must make lots of outbound SSL connections to a third party REST API via SSL. OpenSSL is used to create establishment of the secure connections with the remote server. After initialization of the ssl_connection I register the returned file descriptor with our epol…