If I have an executable in /usr/bin and call it while I'm located at ~/dev/wikis/ (that is user@HAL:~/dev/wikis$ the_executable), the ioutil.ReadFile("file.txt") function in the executable will look in /home/user/dev/wikis/file.txt, but is it possible to make it look in /usr/bin/file.txt instead without the user or developer knowing beforehand that the executable will be located in /usr/bin (it could just as well be located in /home/user/dev/my_program/the_executable)?
And then to add a layer of complexity, another situation, say I call the executable from a symbolic link in /usr/bin with the "source" of the executable actually being in /home/user/dev/my_program/the_executable, and I want the program to know about /home/user/dev/my_program/ in this case, dynamically, rather then /usr/bin.
In short: How can an executable dynamically resolve its location on the filesystem or its actual "resting place" vs the working directory of the user (which can easily be gotten through os.Getwd() and which other commands like ioutil.ReadFile use, or use something comparible, for resolving paths).
My best bet is that I have to get the PID of the running program (os.Getpid) and then somehow use that integer to access information about the instance of the program running under that PID, and hopefully that information contains a string of its directory which I can then use.
In Linux (and perhaps in other Unixy systems) you'll find a symbolic link to the actual executable running as pid under /proc/pid/exe, checking that one will give what you want if it is a binary. If it is a script of some sort, that will probably just give the interpreter.
But note that it is perfectly possible to start a process and delete the executable while it is running, leaving either a dangling link or just nothing.