flock | Copy Flock package by Ivan Popivanov

There are a few adjustment you need to make:

• don't increase i manually in the loop but use step value in range(start, end, step). The step value here would need to be 5.
• You need to append the results to the list, otherwise you are just replacing the value over and over again and only the last value will be stored in the variables at the end of the for loop.
• you probably want to strip the newlines \n (but this is optional) using rstrip("\n").
• you probably also want to have all the possibilities for an answer in an array (but this is also optional). You can do that by using split("#") on the relevant string.

I believe channels can throw off this calculation.

Try:

Well, according to some nginx doc (see the "Log Rotation" section), nginx keeps the log file open so when you rename it, nginx just keeps writing to the same file descriptor it had which is now the renamed file. Until you signal it, it won't make a new file. So renaming the log file won't do anything to nginx. According to that, it will just keep writing to the renamed file.

So, I guess the answer to "Is renaming a safe way of locking files?" for nginx is "No". It doesn't lock anything.

Since there was no input example, I used your "Output I have" as input.

I also checked if the whole line contains the word terror or bird, but you can change it if you need the column where it is.

Extract the first character with map from the list:

flock -n creates/checks for a lock at the given /var/lock.. location

No, flock works on file descriptors.

/var/lock is a typical location for system administrators to put locks for global utilities. Like for example for package managers (pacman, apt-get etc.). You can use (ok, almost) any file anywhere with flock.

Let's say generally, flock is a property associated with a file referenced by a file descriptor. The number 100 is not significant, it has to be any open for writing file descriptor.

100>/var/lock/dobackup.lock redirects file descriptor 100 to file /var/lock/dobackup.lock. flock -n 100 applies flock on the file descriptor 100. When file descriptor 100 is closed (which happens when process terminates) then flock associated with that process is lifted automatically.

See Wikipedia for file descriptor, see man 2 flock and man 2 fcntl.

ok, looks like i found my solution here: https://gitlab.alpinelinux.org/alpine/aports/-/issues/12406

quote from Lyle Franklin:

I hit this error when trying to build a cross-platform ARM64 docker image from a AMD64 host. However, running docker run --rm --privileged linuxkit/binfmt:v0.8 or update-binfmts --enable prior to running the build seems to avoid the issue. My understanding Docker will try to use upstream QEMU if it is installed and registered with the kernel, otherwise Docker will fallback to using a built-in forked version of QEMU. The build error above only showed up for me with the forked QEMU.

So I will probably add docker run --rm --privileged linuxkit/binfmt:v0.8 && update-binfmts --enable to my pipeline file if I encounter the error again, for now running it once solved the issue.

how to open file with O_CLOEXEC flag

It's not possible. You have to write small a Bash built-in that will open the file descriptor. I would imagine:

Try this: