I have a TSV file with 4 columns in this format The 4th column is a date string Example : 2020-12-09 12:34:22 I want every row with the same date to go into its own file For example, file 20201209 should have all rows that start with 2020-12-09 in the 4th column file 20201210 should have all rows that start
Why is there a while loop in wait function of a semaphore, when if can be used too?
this is my code: there is a while loop in the wait function of a semaphore, can’t I use an if statement simply? Answer Because we can’t assume that after a thread is woken up and it requires the lock another thread has not already come along and taken the resource this is guarding:
How to have Bash set -x only apply to the very next command without creating child processes and without calling set +x
This is limited to Bash only, and the answer needs to work on all Bash versions without exception. I do this now: and it does what I expect: The op1 is not transcribed, the op2 is transcribed, and then op3 is not. And this has the feature that if “code wedging” occurs whereby op2 has a lot of line…
Why does the Qemu run differ from the native run?
What did i do? I ran qemu-x86_64 -singlestep -d nochain,cpu ./dummy to dump all the registers of a dummy program after each instruction and used grep to save all the RIP values into a text file (qemu_rip_dump.txt). I then singlestepped the dummy program with ptrace and dumped the RIP values after each instruc…
modifying u-boot environment in kernel init
I’m trying to modify a u-boot env arg within the kernel code. I’ve found boot_command_line var in main.c and setup.c, which contains an arg, so that made me think it is possible, however, I coudn’t find where this var is being updated with the u-boot env arg value, or how to get a different …
Tcl refuses to set 76800 baud rate for serial channel on Linux
I have an FTDI USB/serial device at /dev/ttyUSB0. I set up my channel with which works just fine for Tcl on Windows. On Linux, baud rate queries show and I get all the garbage you’d expect from trying to communicate at the wrong baud rate. I saw this previous post: fconfigure refuses to set baud rate to…
How to configure Key for IdentityServer4 on Linux
I have an asp.net core app with IdentityServer4. In production it requires a key. On Windows Server, I deployed it OK – created a self-signed certificate and added LocalMacine/my as the key location. How can I do the same on Linux? appsettings.json config on Windows – need syntax for Linux: Answer…
D-Bus returns UnkownMethod – saying No such interface on object at path
I want to write a short program, which triggers the Thumbnail creation for all pictures on my network share recursively (e.g. over night) – so that when I access a folder in Thunar, the thumbs are displayed immediately. I would say, that when I can access the API via gdbus call, then the system is setup…
what is segment 00 in my Linux executable program (64 bits)
Here is a very simple assembly program, just return 12 after executed. It can be built and executed correctly: But the size of a.out is big, it is more than 4k: I try to understand it by reading elf content: it is strange, segment 00 is aligned by 0x1000, I think it means such segment at least will occupy 409…
Read number from stdin and save as integer directly, using read() function
when I execute this code, it returns just random integer like 724109877 Why this happend? also glad to hear if someone tells me right way to read number from stdin and save as integer Answer You can do that by reading a line and convert it to a number later: Note that nb_bytes will include the newline charact…