1

I'm tired of typing manage.py startserver 10.211.55.4:4000, so decided to make an alias for that. Only thing is: the port sometime changes. So I did this in bash profile:

function runserver() {
   python manage.py runserver 10.211.55.4:$1
}

But then when I call it: runserver 3000, it starts it, but immediately stops saying:

"Error: That IP address can't be assigned-to". However if I type the same thing right into command line it works with no complains.

1
  • Sanity check: do you run bash --login all the time? Function definitions should be in .bashrc, not .bash_profile, since .bash_profile is only read by login shells. Jun 3 '14 at 22:38
3

Along the lines of your original attempt, you could adjust that function to the following:

function runserver() {
    python manage.py runserver 10.211.55.4:$PORT
}

and then call it like so:

PORT=3000 runserver
5
  • Alternatively of course, you could always just whip up a quick bash or python script that takes your port argument, and stick it somewhere in your path. Jun 3 '14 at 20:46
  • That wouldn't make any difference apart from the less convenient syntax. The command that's executed in the end is exactly the same. Jun 3 '14 at 21:02
  • The trick is that his function definition is in his bash profile. $1 here refers to arguments given to the .bash_profile, not the function itself. Jun 3 '14 at 21:45
  • 2
    This is wrong. $1 in a function definition refers to the argument of the function. Jun 3 '14 at 22:37
  • I must admit you are correct, I was mistaken. Given that, I see nothing incorrect with the original function definition as provided in the question. Jun 3 '14 at 23:02
3

This is actually an error you get back from Python/Django when you feed it an IP address it can't bind to (one that isn't part of the system) as shown in a real, just-run example below:

$ python manage.py runserver 123.123.123.123:8000
Validating models...

0 errors found
June 03, 2014 - 22:36:58
Django version 1.5.7, using settings 'tv.settings'
Development server is running at http://123.123.123.123:8000/
Quit the server with CONTROL-C.
Error: That IP address can't be assigned-to.

So you either need to fix your IP address (look at the output of ifconfig --all to see what's available) or you just bind to all of them with:

function runserver() {
    python manage.py runserver 0:$1
}

The bash side of things is sound.

0

You're doing it right.

I suspect that you're running into a networking issue in your testing, and the fact that the failed test used the function was a coincidence. When you close a TCP connection, the port remains in use for a small amount of time (30s), in case there were pending packets that were not yet received (packets may arrive out of order). This is the TIME_WAIT state. To allow a new server to restart immediately, set the SO_REUSEADDR flag with setsockopt (there's an example in the Python socket documentation).

1
  • but why does it work when I type the same thing right to the console?
    – iLemming
    Jun 3 '14 at 21:27
0

We can make alias with group command { list; } and here-string <<< redirection. The key goal is to redirect stdin to the command. There's a couple of ways presented below

alias runserver='{ xargs -I % python manage.py runserver 10.211.55.4:%;} <<<'

alias runserver='{ IFS= read -r port; python manage.py runserver 10.211.55.4:"$port";} <<<'

alias runserver='{ port=$(line); echo python manage.py runserver 10.211.55.4:"$port";} <<<'

Note the space after { and semicolon before } are required.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.