Where do library C header files go on Linux
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?
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.
3 Answers 3
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 it should also get it from the right place.
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?
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
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.)
@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.
How can I find the header files of the C programming language in Linux?
When I write C programs in Linux, and then compile them using gcc, I am always curious about where those header files are. For example, where stdio.h is. More generally, where is stdbool.h ? What I want to know is not only where it is, but also how to get those places, for example, using shell command or using the C programming language.
10 Answers 10
gcc -H . will print the full path of every include file as a side-effect of regular compilation. Use -fsyntax-only in addition to get it not to create any output (it will still tell you if your program has errors). Example (Linux, gcc-4.7):
$ cat > test.c #include #include ^D $ gcc -H -fsyntax-only test.c . /usr/lib/gcc/x86_64-linux-gnu/4.7/include/stdbool.h . /usr/include/stdio.h .. /usr/include/features.h . /usr/include/x86_64-linux-gnu/bits/predefs.h . /usr/include/x86_64-linux-gnu/sys/cdefs.h . /usr/include/x86_64-linux-gnu/bits/wordsize.h . /usr/include/x86_64-linux-gnu/gnu/stubs.h . /usr/include/x86_64-linux-gnu/bits/wordsize.h . /usr/include/x86_64-linux-gnu/gnu/stubs-64.h .. /usr/lib/gcc/x86_64-linux-gnu/4.7/include/stddef.h .. /usr/include/x86_64-linux-gnu/bits/types.h . /usr/include/x86_64-linux-gnu/bits/wordsize.h . /usr/include/x86_64-linux-gnu/bits/typesizes.h .. /usr/include/libio.h . /usr/include/_G_config.h . /usr/lib/gcc/x86_64-linux-gnu/4.7/include/stddef.h . /usr/include/wchar.h . /usr/lib/gcc/x86_64-linux-gnu/4.7/include/stdarg.h .. /usr/include/x86_64-linux-gnu/bits/stdio_lim.h .. /usr/include/x86_64-linux-gnu/bits/sys_errlist.h The dots at the beginning of each line count how deeply nested the #include is.
what is default path for header file included in c program?
Try running gcc -v -E — . When I do, part of the output is as follows:
#include search starts here: /usr/lib/gcc/i686-linux-gnu/4.6.1/include /usr/local/include /usr/lib/gcc/i686-linux-gnu/4.6.1/include-fixed /usr/include/i386-linux-gnu /usr/include It’s not an answer to the gstreamer question, but I hope this still helps!
/usr/local/include /usr/include If you use another path, you can add in your compile command with -I flag. In your case, assuming you have a /usr/local/gst/include directory, you may add -I/usr/local/gst/include and use #include
The path searched depends on the implementation (and current configuration). The correct way to find the include path is to use pkg-config
pkg-config --cflags gstreamer it shows this error —> Package gstreamer was not found in the pkg-config search path. Perhaps you should add the directory containing `gstreamer.pc’ to the PKG_CONFIG_PATH environment variable No package ‘gstreamer’ found
@Mr.32 Perhaps you need to specify a version. Or maybe gstreamer isn’t correctly installed. Look in /usr/lib/pkgconfig and /usr/share/pkgconfig .
@Mr.32: As cnicutar has pointed out you need to use pkg-config. For gstreamer it is not just gstreamer, it is gstreamer-
Where are package library and header files installed?
After downloading and installing a package in Ubuntu, how can I check where the library and header files were written to? I believe that this has something to do with the package’s .pc file, but I do not know how to find that file either. For example, I have downloaded the PCL (Point Cloud Library) package, and then in a sample CMakeLists.txt file, I have been given the following:
include_directories($) link_directories($) add_definitions($) Where are these environment variables defined, and how can I see them? If I compiled the libraries from source rather than through a package, will this be any different? Will a .pc file be created automatically?
That just returns an empty line. However, compiling my project as above works fine so it must be using the PCL libraries. Is it searching anywhere else?
If you installed a debian package you can see the content via dpkg -L
I had similar confusions. You can check to what values $ resolves to by using message command in your CMakeLists.txt i.e. add this line: message(«$) or message(«PCL_INCLUDE_DIRS = » $) . It will display the result when you run cmake .. Do the same for other macros/variables i.e. $ and $
2 Answers 2
If you install the package containing the libpcl development files
sudo apt-get install libpcl-dev You can list the installed files
an see the location of all headers.
. /usr/include/pcl-1.7/pcl/filters/fast_bilateral.h /usr/include/pcl-1.7/pcl/filters/voxel_grid_covariance.h /usr/include/pcl-1.7/pcl/filters/voxel_grid_occlusion_estimation.h /usr/include/pcl-1.7/pcl/filters/median_filter.h /usr/include/pcl-1.7/pcl/filters/crop_box.h /usr/include/pcl-1.7/pcl/filters/voxel_grid_label.h /usr/include/pcl-1.7/pcl/filters/covariance_sampling.h /usr/include/pcl-1.7/pcl/filters/random_sample.h /usr/include/pcl-1.7/pcl/filters/normal_refinement.h /usr/include/pcl-1.7/pcl/filters/project_inliers.h /usr/include/pcl-1.7/pcl/filters/fast_bilateral_omp.h /usr/include/pcl-1.7/pcl/filters/clipper3D.h /usr/include/pcl-1.7/pcl/filters/convolution.h /usr/include/pcl-1.7/pcl/filters/passthrough.h /usr/include/pcl-1.7/pcl/filters/conditional_removal.h /usr/include/pcl-1.7/pcl/filters/impl /usr/include/pcl-1.7/pcl/filters/impl/frustum_culling.hpp /usr/include/pcl-1.7/pcl/filters/impl/conditional_removal.hpp /usr/include/pcl-1.7/pcl/filters/impl/convolution_3d.hpp /usr/include/pcl-1.7/pcl/filters/impl/voxel_grid_covariance.hpp /usr/include/pcl-1.7/pcl/filters/impl/fast_bilateral_omp.hpp /usr/include/pcl-1.7/pcl/filters/impl/project_inliers.hpp /usr/include/pcl-1.7/pcl/filters/impl/morphological_filter.hpp /usr/include/pcl-1.7/pcl/filters/impl/crop_box.hpp /usr/include/pcl-1.7/pcl/filters/impl/covariance_sampling.hpp /usr/include/pcl-1.7/pcl/filters/impl/local_maximum.hpp /usr/include/pcl-1.7/pcl/filters/impl/plane_clipper3D.hpp /usr/include/pcl-1.7/pcl/filters/impl/bilateral.hpp /usr/include/pcl-1.7/pcl/filters/impl/voxel_grid_occlusion_estimation.hpp .