Question

I am just starting to use terminal for my programming needs. In a lot of Django tutorials I see people say, for example, I should type this in terminal:

manage.py runserver

However when I do this it says:

bash: manage.py: command not found

I get it to work when I do: python manage.py runserver, however I would like to understand why this works and the other method doesn’t. I guess these are some very basic things but I thought I’d ask here.

Answer 1

bash(1) will search your PATH environment variable to find programs to execute. PATH does not normally contain your “current working directory” (.) because that opens people up to trivial security problems:

cd /home/unsavory_character/
ls

If unsavory_character places an executable in /home/unsavory_character/ls that adds his or her ssh(1) key to your ~/.ssh/authorized_keys file, you’d be in for a surprise — he or she could log in as you without a password.

So systems these days don’t add the current working directory to the PATH, because it is too unsafe.

The workaround:

./manage.py runserver

Of course, that assumes your current working directory is whichever directory contains the manage.py script. That might be a safe assumption. If you’d like to be able to execute it from anywhere in the filesystem, you can add the directory to your PATH by editing your ~/.profile or ~/.bash_profile or ~/.bashrc file. (If one of them already exists, pick that one. I seem to recall others with PATH problems on OS X found one or the the other file worked well, and the other one never got executed.)

(In my case, I have a bunch of self-written utilities in ~/bin/, but yours might be elsewhere. Change the paths as appropriate.)

if [ -d "$HOME/bin" ] ; then
    PATH="$HOME/bin:$PATH"
fi