I can see >> is append and > is overwrite but I do not know what < < does with a space in the middle. What does this do, and does the direction of these arrows matter? For example: Answer < redirects a file as input to a command. <(…) is a process substitution – it is replaced…
Tag: linux
libuv: difference between fork and uv_spawn?
Recently I have been playing around with Libuv. I don’t get the programming model as far as child processes are concerned. For example look at the following code: Here the output printed on console is: In my understanding uv_spawn acts like fork(). In child process the value of r is 0 and in parent proc…
Filtering access logs by last 15 minutes with awk not working when there are no entries
I have an apache access log with the below format and I’m trying to use the awk command to filter out the requests by the last 15 minutes. It works fine when there are entries but returns everything when there are none found in the last 15 minutes. Access log format Answer It’s not possible to com…
How to include device tree overlay into Raspberry Pi CM4
I would like to include UART3 and UART5 overlay to enable them, using Yocto. They are already delivered with the whole package (https://github.com/raspberrypi/linux/blob/rpi-5.10.y/arch/arm/boot/dts/overlays/uart3-overlay.dts) I added to my main image recipe lines: I have also added .bbappend to enable them i…
How to stream 4k video in jetson xavier using udpsink in gstreamer
I am using a jetson xavier NX and i have connected 4k camera to it. I want to stream 4k video using gstreamer and RTP and store the streamed video data as an mkv file on another jetson. However my data is getting compressed a lot and I am not able to send it in 4k even though 4k is
How do I pause other processes when user input / confirmation is required Subprocess Python
If I have a script (process run.py) that will run 3 subprocesses A.py, B.py, C.py (3 scripts called at same time through process run.py). The operation is fine. However say in b.py i have a line such as (pref) How can i get subprocess of A.py and c.py to wait/pause for 5seconds, in order for user to enter y o…
Ansible Replace the string variable in uri module
I want to download the filebeat7.15.2 binaries form artifactory. I am passing the version in my playbook as 7-15-2, but want to change in the playbook to 7.15.2 in uri module only. My binary is stored in example.com/artifactory/mvn-public-local/com/dbdb/rf/devops/filebeat/7-15-2/filebeat-7.15.2-linux-x86_64.t…
Non variable recognition on Syspass API Bash Script
When i input a variable on the curl with the json indexed, it takes the string value of the variable, if i scaped the double-quotes, it returns me a sintax error because of in a json request u have to input the data with double-quotes. Example: The curl json request works if i input the data manually, but wit…
scanf does not work in batch mode programming
I am facing issue in my code it works perfectly fine when I try to execute in linux terminal in interactive mode shown here enter image description here but when trying to do in batch mode I am getting an unexpected behaviour from program I do not know exactly is it the address like enter image description he…
Both registering signal handler for SIGSEGV and still being able to create full crash dump from OS
We are using the standard pattern of registering custom signal handler for SIGSEGV with sigaction and then when segmentation fault occurs using the backtrace function to walk the stack and print it to some file. It is nice feature to have the backtrace in logs but it disables the OS writing the full dump of t…