Location of configuration in unix program

Question

I want to write a unix/linux program, that will use a configuration file.

My problem is, where should I put the location of the file?

I could "hardcode" the location (like /etc) into the program itself.

However, I would like it, if the user without privileges could install it (through make) somewhere else, like ~.

Should the makefile edit the source code? Or is it usually done in a different way?

Answer 1

Create some defaults:

• /etc/appname
• ~/.appname

Then if you want to allow these to be overridden have your application inspect an environment variable. e.g.

• $app_userconfig
• $app_config

Which would contain an override path/filename.

Lastly add a command line option that allows a config to be specified at runtime, e.g.

• -c | --config {filename}

Answer 2

It is common to use a series of places to get the location:

1. Supplied by the user as a command line argument (i.e. ./program -C path/to/config/file.cfg).
2. From an environment variable (char *path_to_config = getenv("PROGRAMCONFIG");).
3. Possibly look for a user specific or local version (stat("./program.cfg") or build up a strig to specify either "$HOME/.program/config.cfg" or "$HOME/.program.cfg" and stat that).
4. Hardcoded as a backup (stat("/etc/program/config.cfg",...)).

Answer 3

keeping a global config file under /etc/prgname is a standard. Also allowing a .local config file for individual users that will override the global settings would allow each user to personalize the program to their preference.