I have a java process A that calls FileOutputStream.flush() to flush the content, and have another process B to read the file content. In most cases, the process B reads the content fine. However, sometimes B reports getting incorrect content. My question is, if the writer process crashes right after calling …
Directory: Is a directory
I’ve set up a cron job to run a Python script to scrape some web pages. /etc/crontab However, the emails are informing me that… /bin/bash: /usr/bin: Is a directory When I manually run the script, it pipes data into my database, but when the cron job executes the script, nothing… What does th…
Expo/GenyMotion throws “ADB server didn’t ACK” when running project
I’m trying to set up a React Native project using GenyMotion and Expo on Ubuntu. However, when I click the ‘Device’ button in Expo to package the app onto the emulator, I get the following error in the Expo console: I initially tried to use React Native through Android Studio, with the inbui…
jq array of hashes to csv
So I have a data source like this: I want to get output like this: Using a fake parameter seems like a hack and then needs to be clean up by sed to work. How do I do this with just jq. Answer Instead of trying to put literal newlines in your data, split the data into separate arrays (one
Draw table in C — like table on manual page of Linux
I want to make nice tables like you see on some manual page of Linux documentation in C programming language. Is there any library or functions to create a table like them. For example a table that you can find on man syslog like the following, produced by running man syslog: Answer You can take a look at the…
why does my ffmpeg process wait forever without stdin parameter to subprocess.run?
I am using the python subprocess module to call ffmpeg like this: This works fine. An example call: What I want to know is why it doesn’t work when I omit the stdin parameter. In this case the ffmpeg process waits forever iff I start my program as a background process in the shell. Running in the foregr…
How can I find all syscalls that have to be whitelisted for seccomp?
I have an existing program that I would like to sandbox using seccomp (v2). How can I find what seccomp rules I need to allow for the program? I’ve tried adding seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(…), 0) for all syscalls printed by strace -xfc a.out, but apparently that wasn’t enough, s…
Python does not find custom installed modules when running from a cronjob
I’m trying to set a python script to run every two minutes using a cronjob, the crontab line is below. The python script is called by a shell script, script.sh, posted below. This python script starts a selenium webdriver, gather some data and saves it to a csv file. A snippet is also bellow. crontab Th…
Serial port hangs on close()
I developed this simple kernel module, which emulates a serial port by using a FIFO queue and a timer (read from hardware : out from the queue, write to hardware : insert in the queue). Source code is shown next. Then, I wrote a simple test-application which configures the port settings (baud rate, parity, st…
Unable to substitute a custom variable in Authorization header value in curl
I am trying to use $timestamp and generate hash. I see $timestamp value is not getting assigned and it’s always same. My request:– Output[Request Authorization headers] 20180701T12:33:56+0000 is the correct value which i want to get substituted in ‘$(echo -n $timestamp’ but it’s …