Embarrassingly basic question. sudo apt-get install libmemcached6 - where do the .h's and .o's or .so's live in a typical install on a Linux machine (Ubuntu)? And, how do I make sure g++ can pick them up?
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g++ can pick them up if they are properly installed because they should be in the PATH. Otherwise, you could compile the library yourself statically and place the output somewhere in a folder of your choice.Mihai Todor– Mihai Todor2012-05-24 00:01:51 +00:00Commented May 24, 2012 at 0:01
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The question is which folder to put them inCoffeeTableEspresso– CoffeeTableEspresso2020-05-18 04:48:45 +00:00Commented May 18, 2020 at 4:48
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3 Answers
They go to /usr/include and /usr/lib. If you use the -l option (for the libraries) it should find them from these standard places. If you include using <file.h> it should also get it from the right place.
8 Comments
djechlin
Found the so in /usr/lib. No header in /usr/include. Is this likely something not included in an apt-get install and I'll just need to acquire the source myself?
mohaps
mostprobably your library has a -dev version that installs the header and this one just installs the runtime requirements (aka the .so) try doing apt-cache search libmemcached6 and see if there's a libmemcached6-dev package for development files. that will add the header file
djechlin
Thanks, I needed the -dev version. g++ myfile.cpp works clean now.
djechlin
Linking with -lmemcached seems like it compiles but fails to link the C functions in, not sure how to tell where to find them (or where they are.)
mpontillo
@djechlin, try running
objdump -T /usr/lib/libmemcached.so.6 and checking to make sure the names match what you have in your code. |
On Ubuntu (and other Debian variants) you can use the dpkg command to find out. For example:
$ dpkg -L libxml2
/.
/usr
/usr/share
/usr/share/doc
/usr/share/doc/libxml2
/usr/share/doc/libxml2/AUTHORS
/usr/share/doc/libxml2/NEWS.gz
/usr/share/doc/libxml2/TODO.gz
/usr/share/doc/libxml2/copyright
/usr/share/doc/libxml2/README
/usr/share/doc/libxml2/changelog.Debian.gz
/usr/share/doc/libxml2/README.Debian
/usr/lib
/usr/lib/libxml2.so.2.7.8
/usr/lib/libxml2.so.2
As you can see, Debian packages don't typically include the .h files; those are normally in corresponding -dev packages. So you can find the header files here:
$ dpkg -L libxml2-dev
/.
/usr
/usr/share
/usr/share/doc
/usr/share/doc/libxml2-dev
/usr/share/doc/libxml2-dev/AUTHORS
/usr/share/doc/libxml2-dev/NEWS.gz
/usr/share/doc/libxml2-dev/TODO.gz
/usr/share/doc/libxml2-dev/copyright
/usr/share/doc/libxml2-dev/README
/usr/share/doc/libxml2-dev/changelog.Debian.gz
/usr/share/aclocal
/usr/share/aclocal/libxml2.m4
/usr/share/man
/usr/share/man/man3
/usr/share/man/man3/libxml.3.gz
/usr/share/man/man1
/usr/share/man/man1/xml2-config.1.gz
/usr/include
/usr/include/libxml2
/usr/include/libxml2/libxml
/usr/include/libxml2/libxml/HTMLtree.h
/usr/include/libxml2/libxml/tree.h
/usr/include/libxml2/libxml/xmlreader.h
/usr/include/libxml2/libxml/xmlschemastypes.h
...
As for gcc, the manual explains how it searches for header files. Note that this is different and separate from using -l to instruct the linker to link with a certain library.
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On Linux and the majority of the Unix-based systems, the libraries may be found on either of these two locations:
- /usr/lib/
- /usr/local/lib/
The difference between these two locations is that the latter is used for the third party libraries. So if you have published your own library or have installed one from a third party repository (for instance ppa),those files should go to /usr/local/lib.
The storage of header files can be understood using the above analogy. The folders are:
- /usr/include/
- /usr/local/include/
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