fds | The go-to FirewallD CLI app | Firewall library

Set the close-on-exec flag for those file descriptors you don't want to carry over to the child processes. Either by setting the O_CLOEXEC flag upon opening, or later with fcntl set FD_CLOEXEC.

Before you ask, O_CLOEXEC != FD_CLOEXEC.

This seems to be imprecisely documented. While MAKEFLAGS has the flags like e.g. -s and -k as ks in it, the -j flag gets processed in another way: it is not stripped of the leading dash - AND it is not visible in the first pass of processing the makefile. Only when rules are executed, MAKEFLAGS receives a value, albeit a processed form of the one you gave. -j3 elicits a -j3 --jobserver-auth=3,4 response from the command line transcriber of make, while -j stays -j. So what does this mean for us? Obviously the feature to detect the requested parallelism at runtime is not stable or there are some good reasons not to access them (which is the case most of the time when you encounter exceptional behaviour in GNU tools), so maybe you can give us more information on what you are trying to achieve - maybe there is a way to circumvent accessing the command line.

According to man pages, dprintf is a POSIX extension, not a standard library function, so it is not equivalent in terms of portability.

As far as their implementation in GLIBC is concerned, both printf and dprintf call __vfprintf_internal, but note that dprintf does also this (done != EOF && _IO_do_flush (&tmpfil.file) == EOF) which suggests flushing the buffer after the write. printf, on the other hand, does not.

I'd try fiddling with buffering, i.e. setbuf, fflush or similar on the stdout and see if that helps.

Download web driver for firefox : https://github.com/mozilla/geckodriver/releases

then unzip file on default directory

tar -C /usr/local/bin/ -xvf geckodriver-v0.30.0-linux64.tar.gz

Add the chosen geckodriver directory to PATH

export PATH=$PATH:/YourDirectory

Create python file main.py

I found the solution, I did a casting to (UNITCallback*) and it worked like a charm. here is the code:

You seem to have forgotten that when connected to a pipe stdout is fully buffered.

You need to explicitly flush stdout for the data to actually be written to the pipe. Since the data isn't flushed, there's nothing in the pipe to be read, and the read call blocks.

So after the printf call you need fflush(stdout).

Use with Series.reindex with MultiIndex.from_product and add values to lists with unique values:

A pipe is two “files” that share a buffer and some locking or control semantics. When you write into the pipe, the data is put into the buffer. When you read from a pipe, the data is taken from a buffer.

There is nothing in the pipe that moves data to some output device.

If you use dup2 to duplicate the read side of the pipe into the standard output file descriptor (number 1), then all you have is the read side of the pipe on file descriptor 1. That means you can issue read operations to file descriptor 1, and the system will give your program data from the pipe.

There is nothing “special” about file descriptor 1 in this regard. Putting any file on file descriptor 1 does not cause that file to be automatically sent anywhere. The way standard output works normally is that you open a terminal or some chosen output file or other device on file descriptor 1, and then you send things to that device or file by writing to file descriptor 1. The operating system does not automatically write things to file descriptor 1; you have to issue write operations.

When fd1 is removed and same is dup to fd2 then kernel does not remove open file description but does remove entry from file descriptor table i.e internal data struct in kernel still remain intact but not associated with fd1 index anymore

Internally epoll fd keeps interest list in kernel data structure where it understand what all open file description needs to be cleaned up when close for one of interest list is invoked. Following link does have more information. https://unix.stackexchange.com/questions/195057/what-is-an-open-file-description