I just downloaded some new header files and have a folder of them that I wish to make available. First, I would like to make them available to any file wishing to use them. So, I would like to be able to include the new header file (call it newheader.h) where I want, just like math.h, for example. Where should I put it?
Second, I wish to make these files available to all users. I have root permissions. Is there a special directory I need to put it in? Thanks so much!
Store them in /usr/local/include. From http://tldp.org/LDP/Linux-Filesystem-Hierarchy/html/usr.html, items in this directory are "... safe from being overwritten when the system software is updated", which is important since you do not want the headers files you have downloaded to get clobbered by system updates, which might happen if you put them in /usr/include.
cuba.h in in /usr/local/include, use #include <cuba.h>. If you put foo/cuba.h in /usr/local/include, use #include <foo/cuba.h>.
/usr/local/include itself is in the default GCC include path using (for example) gcc -v -xc -E /dev/null 2>&1 | awk '/#include/,/End/'
Commented
Mar 19, 2018 at 2:00
On MY system, the /usr/local/include/ directory exists, and is empty. The Filsystem Hierarchy Standard says (FHS 3.0) the directory to use is /usr/local/include. Files should be world-readable (0444) and directories should be searchable (0555).
The question is, what do you want to achieve?
Usually you have three scenarios:
$HOME)For the first 2, you should probably use the -I switch to give a path to the headers. The first would likely be -I../mylib/include, the second may be -I/home/user/local_libs/somelib/include.
The third one is a global installation, which should place them in /usr/local/include, but managed by a tool like automake or cmake. When packaging, the maintainer should adapt the installpath and/or the include path to install the headers to /usr/include.
When using automake you may have notices than the --prefix parameter defaults to /usr/local for a safe installation which does not interfere with system packages, while i.e. debian maintainers run ./configure --prefix=/usr in their package scripts. The include path is built from this prefix, so it follows the package installation.
/opt/our-dev-code/include or a copy per user. So I still have a bit the feeling if it is a X Y problem and the proper -I option is a better answer then deploying in /usr/local/include, so I elaborated a bit on the other options.