Location of configuration in unix program

I wan开发者_如何学Pythont 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?

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}

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",...)).

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.

As skaffman says, the canonical locations for things like config files are specified in FHS. There appears to be a convention that a program will read a config file from the directory from which it is run as an alternative to the one in the hard-coded location. You may wish to consider adding a command-line switch that allows a user to specify an alternative config file location, as well.

The makefile shouldn't modify the source directly, but it can pass a folder path/name to the compiler through the -D option. One way to handle it would be to #define something like DEFAULT_PATH to be the default installation path. If the user wants to define a path, the makefile would add -DUSER_PATH=whatever to the compiler options. You would write your code to use USER_PATH if it exists, and DEFAULT_PATH otherwise.