Control stript which is runing in background.

[2QdxY4RzWzUUiLuE at potatochowder.com]

On 2021-01-01 at 03:43:43 +0100,
Regarding "Re: Control stript which is runing in background.,"
jak <nospam at please.ty> wrote:

> Il 01/01/2021 01:43, Cameron Simpson ha scritto:
> > On 01Jan2021 01:21, jak <nospam at please.ty> wrote:
> > > Il 01/01/2021 00:58, 2QdxY4RzWzUUiLuE at potatochowder.com ha scritto:
> > > > Most of the time, I have several shells open, often with their own
> > > > background jobs running.  Limiting write permission on the pipe to "me"
> > > > wouldn't prevent concurrent access.
> > > 
> > > This is true but there would be no difference if this happened through
> > > a socket.
> > 
> > Accessing a socket makes a distinct separate data connection - other
> > openers do not conflict with it. That's the critical difference between
> > a socket and a pipe in terms of functionality, and why sockets have a
> > connect/accept step.
> > 
> > Cheers,
> > Cameron Simpson <cs at cskk.id.au>
> > 
> 
> Maybe the fact that I'm not English and I don't know the language well
> doesn't allow me to express myself clearly. Try it one more time:
> The OP would like to give some command to a script that is running. How?
> With a script that sends commands to it. One of the ways, as mentioned,
> is by using a mini socket server. Given the needs of the OP and the fact
> that sockets are a limited resource in a system, I took the liberty of
> proposing a simple alternative: using a named pipe, also because, IMO,
> sockets, in this case, are an overkill. with a few lines of code in a
> thread in the running script they can allow it to receive commands:
> #-----------------
> import os, errno
> 
> fnpipe = 'cmdpipe'
> 
> try:
>     os.mkfifo(fnpipe)
> except OSError as e:
>     if e.errno != errno.EEXIST:
>         raise
> while True:
>     with open(fnpipe, 'rt', 1) as fifo:
>         for line in fifo:
>             print(line, ends='')
> #-----------------
> 
> Running the command:
> 
> $ cat bible.txt > cmdpipe & cat bible.txt > cmdpipe & cat bible.txt >
> cmdpipe
> 
> the three texts do not mix. IMO, the OP should be enough. after that, I
> know that a pipe is more like a queue than a soket and in this case a
> socket, IMO, is wasted.

Only the OP knows for sure.  :-)   Does the server send data back to the
client that made the request?  Are the requests (and the responses, if
any) small enough to be sent/received atomically?  *If* the answers are
no and yes, then you're right, a named pipe would be good enough.  If
not, then a socket *might* be better.  Until the OP clarifies, we can't
tell.

> greetings, hoping to have been clearer than before.

I think you were clear enough before, but you may not have considered
things the OP did not specify.  One of the hardest parts of software
development is understanding and specifying the actual problem to be
solved.  I've never done that in a second language (I'm nowhere near
fluent in anything other than English); I can only imagine the extra
layers of complexity.