I want to build ffmpeg with support for the av1 codec on CentOS 7. I start by following the instructions here : git clone https://aomedia.googlesource.com/aom mkdir aom_build cd aom_build cmake ../aom make sudo make install This writes a file to /usr/local/lib64/pkgconfig/aom.pc. When I later clone ffmpeg's git repo and try to run ./configure --enable-libaom ..., it complains that pkg-config can't find the aom.pc file. This is because if I run pkg-config --variable pc_path pkg-config, I can see that pkg-config only checks here: /usr/lib64/pkgconfig:/usr/share/pkgconfig It doesn't look in /usr/local/lib64/pkgconfig, where aom.pc is. So far, the only fix I've come up with is to run this instead in ffmpeg's git directory: PKG_CONFIG_PATH=$PKG_CONFIG_PATH/usr/local/lib64/pkgconfig: ./configure --enable-libaom ... This works, but I'd rather just tell libaom to write aom.pc to /usr/lib64/pkgconfig in the first place. Is there any way, when building aom, to tell cmake or make to write the aom.pc file to /usr/lib64/pkgconfig instead of /usr/local/lib64/pkgconfig? In other projects that have a ./configure step, I've seen it possible to specify this with ./configure --pkgconfigdir=/usr/lib64/pkgconfig, but the aom project doesn't have a ./configure script, so I'm not sure what to do here.

I'm trying to build a rust app on fedora within a rustup environment that depends on libudev. At the moment I get the error when trying to compile the app with cargo build --release:

error: failed to run custom build command for libudev-sys v0.1.4

Caused by:
  process didn't exit successfully: /home/me/myApp/target/release/build/libudev-sys-7d615f10fc24f9b2/build-script-build (exit status: 101)
  --- stdout
  cargo:rerun-if-env-changed=LIBUDEV_NO_PKG_CONFIG
  cargo:rerun-if-env-changed=PKG_CONFIG
  cargo:rerun-if-env-changed=LIBUDEV_STATIC
  cargo:rerun-if-env-changed=LIBUDEV_DYNAMIC
  cargo:rerun-if-env-changed=PKG_CONFIG_ALL_STATIC
  cargo:rerun-if-env-changed=PKG_CONFIG_ALL_DYNAMIC
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_PATH
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_LIBDIR
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_SYSROOT_DIR
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR

  --- stderr
  thread 'main' panicked at 'called Result::unwrap() on an Err value: "\"pkg-config\" \"--libs\" \"--cflags\" \"libudev\" did not exit successfully: exit status: 1\n--- stderr\nPackage libudev was not found in the pkg-config search path.\nPerhaps you should add the directory containing `libudev.pc'\nto the PKG_CONFIG_PATH environment variable\nPackage 'libudev', required by 'virtual:world', not found\n"', /home/me/.cargo/registry/src/github.com-1ecc6299db9ec823/libudev-sys-0.1.4/build.rs:38:41

In the past things worked fine on ubuntu (or any debian-based, using the system rust install not rustup) after doing sudo apt install libudev1 && sudo apt install libudev-dev. So far, I've tried or considered: - looking at the advice in https://unix.stackexchange.com/questions/715215/unable-to-find-libudev-pc , most of that advice was particular to someone's homebrew / linuxbrew setup while this question is specific to Fedora with a Rustup installed rust environment. - Tried updating my PKG_CONFIG_PATH and checking things with PKG_CONFIG, specifically: 1. See where the libraries are via yum provides */libudev.pc, which reveals Filename : /usr/lib/pkgconfig/libudev.pc & Filename : /usr/lib64/pkgconfig/libudev.pc 2. Add the lib folders to PKG_CONFIG_PATH in my .bashrc: PKG_CONFIG_PATH=$PATH:/usr/lib/pkgconfig/:/usr/lib64/pkgconfig 3. Start a new shell, run pkg-config --libs --cflags libudev , which still gives an error

Package libudev was not found in the pkg-config search path.
      Perhaps you should add the directory containing `libudev.pc'
      to the PKG_CONFIG_PATH environment variable
      Package 'libudev', required by 'virtual:world', not found

4. Running pkg-config --variable pc_path pkg-config shows /usr/lib64/pkgconfig:/usr/share/pkgconfig - considered doing sudo dnf install libudev , but hesitate since I'm using a rustup environment instead and installing that triggers installing the fedora system version of rust too.

In some RPM specfiles, I see lines like: BuildRequires: pkgconfig(ice) BuildRequires: pkgconfig(libnotify) BuildRequires: pkgconfig(libssl) ... I am not very familiar with pkgconfig but I understand that some installed libraries have a corresponding .pc file which describes them. I have 2 questions: 1. Is this only used for dynamic libraries? 2. How does RPM handle the above in a situation where ice, libnotify, and libssl are NOT found on the system currently or where they are found but there is no corresponding .pc file?

I am writing a little library as a self challenge. I plan to target Linux based systems. I want to add a libname.pc file so as to add support for PkgConfig. Here, is my current file:

prefix=/usr/local
exec_prefix=${prefix}
cphoton_directory=cphoton-0.0
include_directory=${prefix}/include/${cphoton_directory}
library_directory=${exec_prefix}/lib

Name: cphoton-0.0
Description: CPhoton is a basic utility library.
Version: 0.0.0
URL: https://gitlab.com/invitron/cphoton 
Cflags: -I${include_directory}
Libs: -L${library_directory} -lcphoton-0.0
Libs.private:

I wanted to know if this is compatible for both static and dynamic libs. I tried to use pkg-config with --static flag but, it seems to give precedence to .so lib. I also tested it with cmake. It links statically only if the dynamic lib is not available. Is it possible or will I have to provide a separate .pc file for static version? Already visited: - https://stackoverflow.com/questions/27586503/how-to-use-pkg-config-to-link-a-library-statically - https://people.freedesktop.org/~dbn/pkg-config-guide.html

I want to make use of pkg-config in my _Makefile_ to find the link-path for _libspa-0.2_. I observe that pkg-config --libs libspa-0.2 returns nothing. For simplicity, I'll demonstrate the problem by running pkg-config straight from the shell, i.e. not from within my _Makefile_.

$ uname -a
Linux MY_LINUX_PC 5.15.133.1-microsoft-standard-WSL2 #1 SMP Thu Oct 5 21:02:42 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux
$
$ sudo apt-get install -y libspa-0.2-dev
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following package was automatically installed and is no longer required:
  libwebrtc-audio-processing1
Use 'sudo apt autoremove' to remove it.
Suggested packages:
  pipewire-doc
The following NEW packages will be installed:
  libspa-0.2-dev
0 upgraded, 1 newly installed, 0 to remove and 3 not upgraded.
Need to get 0 B/81.7 kB of archives.
After this operation, 625 kB of additional disk space will be used.
Selecting previously unselected package libspa-0.2-dev:amd64.
(Reading database ... 34966 files and directories currently installed.)
Preparing to unpack .../libspa-0.2-dev_0.3.48-1ubuntu3_amd64.deb ...
Unpacking libspa-0.2-dev:amd64 (0.3.48-1ubuntu3) ...
Setting up libspa-0.2-dev:amd64 (0.3.48-1ubuntu3) ...
$
$ pkg-config --libs libspa-0.2

$

Oddly, pkg-config behaves as expected when asked to report _libspa-0.2_'s cflags:

$ pkg-config --cflags libspa-0.2
-D_REENTRANT -I/usr/include/spa-0.2
$

This is the content of _libspa-0.2.pc_:

$ cat /usr/lib/x86_64-linux-gnu/pkgconfig/libspa-0.2.pc
prefix=/usr
libdir=${prefix}/lib/x86_64-linux-gnu
includedir=${prefix}/include

plugindir=${libdir}/spa-0.2

Name: libspa
Description: Simple Plugin API
Version: 0.2
Cflags: -I${includedir}/spa-0.2 -D_REENTRANT
$

...so I was expecting pkg-config --libs libspa-0.2 to return something along the lines of /usr/lib/x86_64-linux-gnu. **Why does pkg-config --libs libspa-0.2 return an empty string?** I'd be grateful if a knowledgeable answerer can describe a little about the relationship between pkg-config, apt-get, and the content of the respective .pc files. I would like to understand the problem/observed behavior specifically with respect to _libspa-0.2-dev_, but if there is a generalization, I'd like to learn that as well. --- **Update**: this is weird -- it looks like pkg-config is doing some (intelligent) formatting/stripping of content for the library link-paths. This is the content of _zlib.pc_ -- something preinstalled (which should rule out my messing up):

$ cat /usr/lib/x86_64-linux-gnu/pkgconfig/zlib.pc
prefix=/usr
exec_prefix=${prefix}
libdir=${prefix}/lib/x86_64-linux-gnu
sharedlibdir=${libdir}
includedir=${prefix}/include

Name: zlib
Description: zlib compression library
Version: 1.2.11

Requires:
Libs: -L${libdir} -L${sharedlibdir} -lz
Cflags: -I${includedir}
$

...and this this what pkg-config reports for its library link paths:

$ pkg-config --libs zlib
-lz
$

...i.e. it seems to be stripping out the -L${libdir} -L${sharedlibdir} part. At least the behavior is consistent...which maybe implies this isn't a "problem" but defined behavior of pkg-config. But I can't figure out the rationale of why it's behaving this way: when and why does it strip out the library link-paths, i.e. -L content?

I'm setting up CI for a Rust application I'm developing that (indirectly) depends on the libudev-sys crate. Part of this CI means building my crate, which means also building libudev-sys. When the workflow runs and it gets to the build stage, cargo fails with this error message while attempting to build libudev-sys:

thread 'main' panicked at /home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/libudev-sys-0.1.4/build.rs:38:41:
  called Result::unwrap() on an Err value:
  PKG_CONFIG_ALLOW_SYSTEM_CFLAGS="1" PKG_CONFIG_ALLOW_SYSTEM_LIBS="1" "pkg-config" "--libs" "--cflags" "libudev" did not exit successfully: exit status: 1
  error: could not find system library 'libudev' required by the 'libudev-sys' crate

Package libudev was not found in the pkg-config search path.
Perhaps you should add the directory containing `libudev.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libudev' found
  note: run with RUST_BACKTRACE=1 environment variable to display a backtrace

I'm struggling to debug this because every change requires committing and pushing to the repo and then waiting for the workflow to run. This is not an error encountered on my own system. According to this page about the ubuntu-latest environment , systemd is installed (which provides libudev), as well as pkg-config from apt (so [this answer] in a related question doesn't apply). I have tried installing systemd with sudo apt-get update and sudo apt-get install systemd, but that shows that systemd is already installed. I also tried updating the PKG_CONFIG_PATH as per this answer , but this did not work either.

I am not a C++ developer or typically work with Conan, CMake, or Makefiles. The first time I had heard of pkg-config was yesterday when conan started erroring on it, unable to resolve a gl package. I managed to get it working with export PKG_CONFIG_PATH="/usr/lib/x86_64-linux-gnu/pkgconfig". Today, I tried to build spotify_player with cargo and it failed, unable to find the alsa library:

--- stderr
  thread 'main' panicked at 'PKG_CONFIG_ALLOW_SYSTEM_CFLAGS="1" PKG_CONFIG_ALLOW_SYSTEM_LIBS="1" "pkg-config" "--libs" "--cflags" "alsa" did not exit successfully: exit status: 1
  error: could not find system library 'alsa' required by the 'alsa-sys' crate

  --- stderr
  Package alsa was not found in the pkg-config search path.
  Perhaps you should add the directory containing `alsa.pc'
  to the PKG_CONFIG_PATH environment variable
  No package 'alsa' found
  ', /home/xevion/.cargo/registry/src/index.crates.io-6f17d22bba15001f/alsa-sys-0.3.1/build.rs:13:18
  note: run with RUST_BACKTRACE=1 environment variable to display a backtrace

I looked around and found alsa.pc at /usr/lib/x86_64-linux-gnu/pkgconfig/alsa.pc. Exporting the variable in the exact same fashion as above fixes it. That said, while it works - something is wrong. I was able to build and install spotify_sound in the exact same way as before a couple months ago. Nothing should have changed. - I've reinstalled all associated libraries with alsa, as well as pkg-config. - I'm working in a new terminal session. - I've confirmed that pkg-config isn't finding it with pkg-config --debug alsa. - Running Pop!_OS 22.04 LTS (Ubuntu 22.04) on a Lenovo ThinkPad X1 Carbon Gen 6. .pc files can be found all over my computer - exporting in my .bashrc seems like a blockhead solution - something is happening on a greater level. How do I fix pkg-config on my machine?

`dpkg: error processing archive /var/cache/apt/archives/libxpm4_1%3a3.5.12-1_amd64.deb (--unpack): trying to overwrite shared '/usr/share/doc/libxpm4/changelog.Debian.gz', which is different from other instances of package libxpm4:amd64 Errors were encountered while processing: /var/cache/apt/archives/libxpm4_1%3a3.5.12-1_amd64.deb` I have tried: `sudo mv /usr/share/doc/libxpm4/changelog.Debian.gz $HOME` Although this seems to be kinda working as it momentarily fixes my upgrade although I need to keep typing this with the new package it tells me to move to $HOME I also tried sudo apt-get --fix-broken install and reconfiguring dpkg but I still have the same issue.

I'm trying to build btrfs-progs from sources, but when I run ./configure I get the error: checking for BLKID... no configure: error: Package requirements (blkid) were not met: No package 'blkid' found Consider adjusting the PKG_CONFIG_PATH environment variable if you installed software in a non-standard prefix. Alternatively, you may set the environment variables BLKID_CFLAGS and BLKID_LIBS to avoid the need to call pkg-config. See the pkg-config man page for more details. blkid is installed in /sbin so, presumably, all its libraries are in the default locations. What do I need to do tell pkg-config where blkid is or am I actually missing a package? FYI: I'm running Debian 8 (sid/unstable) with a 4.1.0 kernel built from github.com/torvalds/linux.git sources about a week ago (commit:g6aaf0da).

I want to build a version of some software that is more recent than the one that is currently available as a stable release Debian package. To do this, however, other than using a more recent version of the source code, I would like to follow, as closely as possible, the build procedure that was used to build the Debian package for this software in the stable release. At the very least, I would like to specify the same configuration flags and the same values for relevant environment variables during the build as was done for the stable release Debian package for this software. **Q:** How can I find the build procedure for a specific (stable release) Debian package?

I'm trying to install openssl inside R, using install.packages('openssl'), but I'm getting an error message: * installing *source* package ‘openssl’ ... ** package ‘openssl’ successfully unpacked and MD5 sums checked Found pkg-config cflags and libs! Using PKG_CFLAGS= Using PKG_LIBS=-lssl -lcrypto -ldl -lz ------------------------- ANTICONF ERROR --------------------------- Configuration failed because openssl was not found. Try installing: * deb: libssl-dev (Debian, Ubuntu, etc) * rpm: openssl-devel (Fedora, CentOS, RHEL) * csw: libssl_dev (Solaris) * brew: openssl (Mac OSX) If openssl is already installed, check that 'pkg-config' is in your PATH and PKG_CONFIG_PATH contains a openssl.pc file. If pkg-config is unavailable you can set INCLUDE_DIR and LIB_DIR manually via: R CMD INSTALL --configure-vars='INCLUDE_DIR=... LIB_DIR=...' -------------------------------------------------------------------- ERROR: configuration failed for package ‘openssl’ * removing ‘/usr/local/lib64/R/library/openssl’ Openssl seems to be installed on the system: $ openssl version -a OpenSSL 1.0.2f 28 Jan 2016 built on: reproducible build, date unspecified platform: linux-x86_64 options: bn(64,64) rc4(16x,int) des(idx,cisc,16,int) idea(int) blowfish(idx) compiler: gcc44 -I. -I.. -I../include -fPIC -DOPENSSL_PIC -DOPENSSL_THREADS -D_REENTRANT -DDSO_DLFCN -DHAVE_DLFCN_H -Wa,--noexecstack -m64 -DL_ENDIAN -O3 -Wall -DOPENSSL_IA32_SSE2 -DOPENSSL_BN_ASM_MONT -DOPENSSL_BN_ASM_MONT5 -DOPENSSL_BN_ASM_GF2m -DSHA1_ASM -DSHA256_ASM -DSHA512_ASM -DMD5_ASM -DAES_ASM -DVPAES_ASM -DBSAES_ASM -DWHIRLPOOL_ASM -DGHASH_ASM -DECP_NISTZ256_ASM OPENSSLDIR: "/usr/local/bin/miniconda2/ssl" I have tried to set PKG_CONFIG_PATH to where **openssl.pc** is located but with no luck. Some help would be much appreciated! I'm running SUSE11 SP2

How do I properly configure pkgconf and libffi to allow the python3 build process to correctly use my libffi version at every step of the build process, in order to import the _ctypes module correctly? Which piece am I missing here? #### Some background I am trying to build Python3 from source to build a GUI with PyQt5, and one of the requirements is a functional libffi-dev library. I don't have sudo permission on this SLES11 machine or write access to the typical library directory, nor are those likely to be granted. I reached out to the team who manages the machines, but they were unwilling to update the whole system set of libraries for my project. I have to resort to building ~30 dependencies from source, and I have little experience in this, but I'm familiar with the configure-->make-->install process. I'm stuck on one final piece of the process (failure to import the _ctypes module), which can be traced back to a missing symbol from the FFI library. *** WARNING: renaming "_ctypes" since importing it failed: build/lib.linux-x86_64-3.9/_ctypes.cpython-39-x86_64-linux-gnu.so: undefined symbol: ffi_prep_cif The libffi library built and installed without any issues, and I can see the files in the local library path, so I have reached the conclusion that there is either a mismatch between the libffi version and another dependency, or pkgconf is unable to locate the library. Based on my observations of the behavior of pkgconf when isolated and instructed to validate the libffi.so file, it is most likely the latter. But, I am virtually a complete novice with this, I've been at this whole build for about a week now, and I'm here typing this question, so I'm clearly open to hearing some other ideas! **Some useful debug**

pkgconf --version 1.7.3 https://distfiles.dereferenced.org/pkgconf/pkgconf-1.7.3.tar.gz 
libffi 3.3 ftp://sourceware.org/pub/libffi/libffi-3.3.tar.gz
Python 3.9.1 https://www.python.org/ftp/python/3.9.1/Python-3.9.1.tgz 

I provided the options to specify a local library directory while making the pkgconf source

./configure --prefix=$HOME/LIBRARIES/--with-system-libdir=$HOME/LIBRARIES/lib:$HOME/LIBRARIES/lib64:/usr/lib:/lib --with-system-includedir=$HOME/LIBRARIES/include:/usr/include

My PKG_CONFIG, PKG_CONFIG_PATH, LD_LIBRARY_PATH, LDFLAGS, and PATH are updated to reflect where the libffi pc files and pkgconf files are located

$ echo $PKG_CONFIG
$HOME/LIBRARIES/bin/pkgconf
$ echo $PKG_CONFIG_PATH
$HOME/LIBRARIES/lib/pkgconfig:$HOME/LIBRARIES/lib64/pkgconfig
$ echo $LD_LIBRARY_PATH
$HOME/LIBRARIES/lib:$HOME/LIBRARIES/lib64
$ echo $LDFLAGS
-L$HOME/LIBRARIES/lib64/ -L$HOME/LIBRARIES/lib
$ echo $PATH
$HOME//LIBRARIES/bin:/usr/local/bin:/usr/bin
$ ls $HOME/LIBRARIES/lib64/libff*
libffi.a libffi.la libffi.so libffi.so.7 libffi.so.7.1.0

**AND YET** pkgconf --validate validation of the library appears to fail, and the Python3 make script notes the undefined symbol. I'm more concerned about the make script; I'm not sure whether pkgconf is actually supposed to error out here. *Update here:* the library is valid according to pkgconf, so this rules out that suspicion. Thank you, telcoM

pkgconf --validate libffi 
$HOME/LIBRARIES/lib/pkgconfig/libffi.pc:9

Adding the configure command for Python3 for clarity

./configure --prefix=$HOME/LIBRARIES --enable-shared --with-system-ffi=$HOME/LIBRARIES/lib

I am trying to run make for an open-source project on my Debian virtual machine but I do not understand why the commands based on pkg-config are not being recognized. One of the commands is as follows: tempgui-qrps.so: tempgui-qrps.cc refpersys.hh tempgui-qrps.hh tempgui-qrps.moc.hh | $(RPS_CORE_OBJECTS) $(RPS_BUILD_CXX) $(RPS_BUILD_COMPILER_FLAGS) \ -shared -o $@ -fPIC -Wall -Wextra -O -g \ $(shell pkg-config --cflags Qt5Core Qt5Gui Qt5Widgets $(RPS_PKG_NAMES)) \ $(shell pkg-config --libs Qt5Core Qt5Gui Qt5Widgets $(RPS_PKG_NAMES)) \ -std=gnu++17 \ $< When I run make on the command line, the output corresponding to the above command looks like this: g++ -std=gnu++17 \ -shared -o tempgui-qrps.so -fPIC -Wall -Wextra -O -g \ \ \ -std=gnu++17 \ tempgui-qrps.cc When I run the make command, I also see these warnings: Package readline was not found in the pkg-config search path. Perhaps you should add the directory containing `readline.pc' to the PKG_CONFIG_PATH environment variable No package 'readline' found Package zlib was not found in the pkg-config search path. Perhaps you should add the directory containing `zlib.pc' to the PKG_CONFIG_PATH environment variable No package 'zlib' found Are both these problems (absence of packages and the pkg-config commands not being processed) related? Some of the details of pkg-config installed on my system are as follows: xxxxx@xxxx:~$ pkg-config --version 0.29 xxxx@xxxx:~$ whereis pkg-config pkg-config: /usr/bin/pkg-config /usr/lib/pkg-config.multiarch /usr/share/man/man1/pkg-config.1.gz

I need to use latest version of pkg-config. So I build it from source with --with-internal-glib --disable-host-tool. However, it cannot find any package without setting PKG_CONFIG_PATH. How can I make it behave like system installed one which contains all default paths?

I'm trying to run the _makefile_, shown in this repo , which is a simple Wayland client. But when I run _make_, it seems that the output of $(WAYLAND) is blank, and it fails to compile due to not being able to find the necessary _wayland-client.h_ header file. cc (GCC) version 5.3.1 on Fedora 23 in bash. Below are some details. My question is, what mistake am I making with my environment that is preventing this _makefile_ from working for me as intended? Contents of _makefile_: WAYLAND=pkg-config wayland-client --cflags --libs CFLAGS?=-std=c11 -Wall -Werror -O3 -fvisibility=hidden hello_wayland: hello_wayland.o helpers.o helpers.h images.bin $(CC) -o hello_wayland *.o $(WAYLAND) -lrt images.bin: images/convert.py images/window.png images/fish.png images/convert.py cat window.bin fish.bin > images.bin clean: $(RM) *.o fish.bin window.bin hello_wayland Output of _make_: > cc -std=c11 -Wall -Werror -O3 -fvisibility=hidden -c -o hello_wayland.o hello_wayland.c hello_wayland.c:6:28: fatal error: wayland-client.h: No such file or directory Notice how the options to _cc_ above seem to be missing the output of $(WAYLAND) specified in _makefile_. If I manually execute _cc_ like this: cc -std=c11 -Wall -Werror -O3 -fvisibility=hidden -c -o hello_wayland.o hello_wayland.c \ -I/home/me/install/include -L/home/me/install/lib -lwayland-client The compilation succeeds. Output of _pkg-config wayland-client --cflags --libs_: > -I/home/me/install/include -L/home/me/install/lib -lwayland-client Contents of *~/.bash_profile*: source ~/.profile source ~/.bashrc Relevant contents of _~/.bashrc_: export WLD=$HOME/install export LD_LIBRARY_PATH=$WLD/lib export PKG_CONFIG_PATH=$WLD/lib/pkgconfig/:$WLD/share/pkgconfig/ export PATH=$WLD/bin:$PATH export ACLOCAL_PATH=$WLD/share/aclocal export ACLOCAL="aclocal -I $ACLOCAL_PATH" Thanks for pointing out something that should probably be totally obvious to me.

*(Learning how to install programs on linux...)* deja-dup source code can be downloaded on its GitHub repo. There is a makefile con the package. Once into the folder I run: santi@eoan:~/deja-dup$ make And get the error: The Meson build system Project name: deja-dup Project version: 40.6 ... Run-time dependency goa-1.0 found: NO (tried pkgconfig and cmake) Run-time dependency json-glib-1.0 found: NO (tried pkgconfig and cmake) meson.build:36:0: ERROR: Dependency "json-glib-1.0" not found, tried pkgconfig and cmake A full log can be found at /home/santi/deja-dup/builddir/meson-logs/meson-log.txt make: *** [Makefile:15: configure] Error 1 I'm running lubuntu eoan, where deja-dup is updated, or almost. I wanted to know what's going wrong for future reference though.

I have a strange problem when trying to install dev-lib/gobject-introspection: >>> Emerging (1 of 9) dev-libs/gobject-introspection-1.42.0 ...... configure: error: Package requirements (glib-2.0 > 2.36.0) were not met: No package glib-2.0 found I have dev-libs/glib-2.42.1 installed, but there is some strange issue with pkg-config: $ pkg-config --modversion glib-2.0 Package glib-2.0 was not found in the pkg-config search path. Perhaps you should add the directory containing glib-2.0.pc to the PKG_CONFIG_PATH environment variable No package 'glib-2.0' found $ echo $PKG_CONFIG_PATH $ And looks like there is no glib-2.0.pc file in /usr/lib/pkgconfig . There is the file /usr/lib32/pkgconfig/glib-2.0.pc, but for previous version of glib-2.38.2 Can anybody explain to me, what can be wrong and how can fix this? I've already asked this question on the gentoo forum , but maybe I'll have better luck here.

I followed a tutorial on GTK which used this command to generate the build flags: $ pkg-config --cflags --libs gtk+-3.0 This outputs coherent flags. From research, I have found that pkg-config searches for .pc files in /usr/lib/pkginfo, usr/share/pkgconfig, in the /local equivalents, and in the folder indicated by the PKG_CONFIG_PATH variable. None of the folders contains the GTK file and the environment variable is not set. Where is pkg-config getting the flags?

My Linux distribution (Antergos) installed the latest version of OpenCV from the repositories (version 3.14.1) about a week ago. For compatibility, I have OpenCV 2 (version 2.4.13.5) installed in a separate folder in my home directory. In order to make compilation easier with g++, I've created aliases in my .bashrc file for each version. This configuration essentially allows me to compile, say a program with only a main.cpp file, by using g++ main.cpp $(opencv2) Below is the relevant code from my .bashrc file: # Programming Related Aliases # OpenCV alias opencv3='pkg-config --cflags --libs opencv' # OpenCV 3 opencv2prefix="$HOME/separate-libs/opencv2/release/installed" # Prefix that serves as the basis for the pathname of the OpenCV 2 directory. export PKG_CONFIG_PATH="$opencv2prefix/lib/pkgconfig" export LD_LIBRARY_PATH="$opencv2prefix/lib" alias opencv2="pkg-config --cflags --libs opencv2" # OpenCV 2 lib, include and runtime specifications for OpenCV 2. Defined in PKG_CONFIG_PATH. This setup worked perfectly until earlier today when I went to compile a larger program (that performs image segmentation) with the OpenCV 2 configuration. At first I thought I had forgotten a necessary build option when compiling OpenCV 2 from source. However, just to check my sanity, I tried compiling a program that I had successfully compiled with OpenCV 2 prior to the aforementioned update. The following was the result: /usr/bin/ld: warning: libImath-2_2.so.12, needed by /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so, not found (try using -rpath or -rpath-link) /usr/bin/ld: warning: libIlmImf-2_2.so.22, needed by /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so, not found (try using -rpath or -rpath-link) /usr/bin/ld: warning: libIex-2_2.so.12, needed by /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so, not found (try using -rpath or -rpath-link) /usr/bin/ld: warning: libHalf.so.12, needed by /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so, not found (try using -rpath or -rpath-link) /usr/bin/ld: warning: libIlmThread-2_2.so.12, needed by /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so, not found (try using -rpath or -rpath-link) /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::globalThreadCount()' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::ChannelList::insert(char const*, Imf_2_2::Channel const&)' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::InputFile::header() const' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::hasChromaticities(Imf_2_2::Header const&)' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::OutputFile::writePixels(int)' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::InputFile::setFrameBuffer(Imf_2_2::FrameBuffer const&)' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::InputFile::readPixels(int, int)' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::Channel::Channel(Imf_2_2::PixelType, int, int, bool)' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::Slice::Slice(Imf_2_2::PixelType, char*, unsigned long, unsigned long, int, int, double, bool, bool)' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::OutputFile::setFrameBuffer(Imf_2_2::FrameBuffer const&)' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::Header::dataWindow() const' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::Header::channels()' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `half::_eLut' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::Header::channels() const' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::Header::~Header()' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::Header::Header(int, int, float, Imath_2_2::Vec2 const&, float, Imf_2_2::LineOrder, Imf_2_2::Compression)' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::InputFile::InputFile(char const*, int)' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::OutputFile::OutputFile(char const*, Imf_2_2::Header const&, int)' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::FrameBuffer::insert(char const*, Imf_2_2::Slice const&)' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::ChannelList::findChannel(char const*) const' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::chromaticities(Imf_2_2::Header const&)' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `half::convert(int)' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::Chromaticities::Chromaticities(Imath_2_2::Vec2 const&, Imath_2_2::Vec2 const&, Imath_2_2::Vec2 const&, Imath_2_2::Vec2 const&)' /home/kvasir/separate-libs/opencv2/release/installed/lib/libopencv_highgui.so: undefined reference to `Imf_2_2::OutputFile::~OutputFile()' collect2: error: ld returned 1 exit status I've tried running sudo ldconfig, as well as checking that my path names are correct. Also, I checked for compatibility issues in the include statements of all files and found no issues. I'm presuming that the package manager's update to the OpenCV 3 installation is what messed everything up. But if that's the case, why? Obviously if the OpenCV installations were in the same folder, I could understand. But both of them appear to be entirely separate and unaware of one another. My only other guess would be something with pkg-config. When I try to compile the image segmentation program that contains object files and more complex code I get: /tmp/ccpvnIWK.o: In function `main': /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/main.cpp:37: undefined reference to `cv::waitKey(int)' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/main.cpp:51: undefined reference to `cv::Mat::convertTo(cv::_OutputArray const&, int, double, double) const' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/main.cpp:74: undefined reference to `cv::imwrite(cv::String const&, cv::_InputArray const&, std::vector > const&)' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/main.cpp:75: undefined reference to `cv::namedWindow(cv::String const&, int)' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/main.cpp:76: undefined reference to `cv::imshow(cv::String const&, cv::_InputArray const&)' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/main.cpp:77: undefined reference to `cv::waitKey(int)' /tmp/ccpvnIWK.o: In function `cv::String::String(char const*)': /usr/include/opencv2/core/cvstd.hpp:602: undefined reference to `cv::String::allocate(unsigned long)' /tmp/ccpvnIWK.o: In function `cv::String::~String()': /usr/include/opencv2/core/cvstd.hpp:648: undefined reference to `cv::String::deallocate()' /tmp/ccpvnIWK.o: In function `cv::String::operator=(cv::String const&)': /usr/include/opencv2/core/cvstd.hpp:656: undefined reference to `cv::String::deallocate()' /tmp/ccpvnIWK.o: In function `cv::Mat::Mat(cv::Mat const&)': /usr/include/opencv2/core/mat.inl.hpp:490: undefined reference to `cv::Mat::copySize(cv::Mat const&)' /tmp/ccpvnIWK.o: In function `cv::Mat::~Mat()': /usr/include/opencv2/core/mat.inl.hpp:704: undefined reference to `cv::fastFree(void*)' /tmp/ccpvnIWK.o: In function `cv::Mat::release()': /usr/include/opencv2/core/mat.inl.hpp:816: undefined reference to `cv::Mat::deallocate()' /tmp/ccpvnIWK.o: In function `cv::Mat::operator=(cv::Mat&&)': /usr/include/opencv2/core/mat.inl.hpp:1383: undefined reference to `cv::fastFree(void*)' /tmp/ccpvnIWK.o: In function `cv::String::String(std::__cxx11::basic_string, std::allocator > const&)': /usr/include/opencv2/core/cvstd.inl.hpp:83: undefined reference to `cv::String::allocate(unsigned long)' Loader.o: In function `void cv::operator>>, std::allocator > >(cv::FileNode const&, std::__cxx11::basic_string, std::allocator >&)': /usr/include/opencv2/core/cvstd.inl.hpp:156: undefined reference to `cv::read(cv::FileNode const&, std::__cxx11::basic_string, std::allocator >&, std::__cxx11::basic_string, std::allocator > const&)' Loader.o: In function `Loader::loadControlParameters(ControlParameters&)': /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/Loader.cpp:16: undefined reference to `cv::FileStorage::FileStorage(cv::String const&, int, cv::String const&)' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/Loader.cpp:17: undefined reference to `cv::FileStorage::isOpened() const' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/Loader.cpp:20: undefined reference to `cv::waitKey(int)' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/Loader.cpp:24: undefined reference to `cv::FileStorage::operator[](char const*) const' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/Loader.cpp:25: undefined reference to `cv::FileStorage::operator[](char const*) const' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/Loader.cpp:26: undefined reference to `cv::FileStorage::operator[](char const*) const' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/Loader.cpp:27: undefined reference to `cv::FileStorage::operator[](char const*) const' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/Loader.cpp:16: undefined reference to `cv::FileStorage::~FileStorage()' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/Loader.cpp:16: undefined reference to `cv::FileStorage::~FileStorage()' Loader.o: In function `Loader::loadOriginalImage(ControlParameters const&)': /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/Loader.cpp:35: undefined reference to `cv::imread(cv::String const&, int)' Loader.o: In function `void cv::operator>>(cv::FileNode const&, int&)': /usr/include/opencv2/core/persistence.hpp:1238: undefined reference to `cv::read(cv::FileNode const&, int&, int)' MeanShift.o: In function `cv::operator*=(cv::Mat&, double const&)': /usr/include/opencv2/core/operations.hpp:254: undefined reference to `cv::Mat::convertTo(cv::_OutputArray const&, int, double, double) const' MeanShift.o: In function `MeanShift::segmentUsingLAB(cv::Mat, unsigned int)': /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:22: undefined reference to `cv::Mat::convertTo(cv::_OutputArray const&, int, double, double) const' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:24: undefined reference to `cv::cvtColor(cv::_InputArray const&, cv::_OutputArray const&, int, int)' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:26: undefined reference to `cv::split(cv::Mat const&, cv::Mat*)' MeanShift.o: In function `MeanShift::segmentUsingLAB(cv::Mat, unsigned int)': /usr/include/opencv2/core.hpp:788: undefined reference to `cv::noArray()' MeanShift.o: In function `MeanShift::segmentUsingLAB(cv::Mat, unsigned int)': /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:28: undefined reference to `cv::normalize(cv::_InputArray const&, cv::_InputOutputArray const&, double, double, int, int, cv::_InputArray const&)' MeanShift.o: In function `MeanShift::segmentUsingLAB(cv::Mat, unsigned int)': /usr/include/opencv2/core.hpp:788: undefined reference to `cv::noArray()' MeanShift.o: In function `MeanShift::segmentUsingLAB(cv::Mat, unsigned int)': /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:29: undefined reference to `cv::normalize(cv::_InputArray const&, cv::_InputOutputArray const&, double, double, int, int, cv::_InputArray const&)' MeanShift.o: In function `MeanShift::segmentUsingLAB(cv::Mat, unsigned int)': /usr/include/opencv2/core.hpp:788: undefined reference to `cv::noArray()' MeanShift.o: In function `MeanShift::segmentUsingLAB(cv::Mat, unsigned int)': /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:30: undefined reference to `cv::normalize(cv::_InputArray const&, cv::_InputOutputArray const&, double, double, int, int, cv::_InputArray const&)' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:32: undefined reference to `cv::merge(cv::Mat const*, unsigned long, cv::_OutputArray const&)' MeanShift.o: In function `MeanShift::segmentUsingHLS(cv::Mat, unsigned int)': /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:44: undefined reference to `cv::Mat::convertTo(cv::_OutputArray const&, int, double, double) const' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:46: undefined reference to `cv::cvtColor(cv::_InputArray const&, cv::_OutputArray const&, int, int)' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:48: undefined reference to `cv::split(cv::Mat const&, cv::Mat*)' MeanShift.o: In function `MeanShift::segmentUsingHLS(cv::Mat, unsigned int)': /usr/include/opencv2/core.hpp:788: undefined reference to `cv::noArray()' MeanShift.o: In function `MeanShift::segmentUsingHLS(cv::Mat, unsigned int)': /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:50: undefined reference to `cv::normalize(cv::_InputArray const&, cv::_InputOutputArray const&, double, double, int, int, cv::_InputArray const&)' MeanShift.o: In function `MeanShift::segmentUsingHLS(cv::Mat, unsigned int)': /usr/include/opencv2/core.hpp:788: undefined reference to `cv::noArray()' MeanShift.o: In function `MeanShift::segmentUsingHLS(cv::Mat, unsigned int)': /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:51: undefined reference to `cv::normalize(cv::_InputArray const&, cv::_InputOutputArray const&, double, double, int, int, cv::_InputArray const&)' MeanShift.o: In function `MeanShift::segmentUsingHLS(cv::Mat, unsigned int)': /usr/include/opencv2/core.hpp:788: undefined reference to `cv::noArray()' MeanShift.o: In function `MeanShift::segmentUsingHLS(cv::Mat, unsigned int)': /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:52: undefined reference to `cv::normalize(cv::_InputArray const&, cv::_InputOutputArray const&, double, double, int, int, cv::_InputArray const&)' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:54: undefined reference to `cv::merge(cv::Mat const*, unsigned long, cv::_OutputArray const&)' MeanShift.o: In function `MeanShift::segmentUsingRGB(cv::Mat, unsigned int)': /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:74: undefined reference to `cv::countNonZero(cv::_InputArray const&)' MeanShift.o: In function `MeanShift::segmentUsingRGB(cv::Mat, unsigned int)': /usr/include/opencv2/core.hpp:788: undefined reference to `cv::noArray()' MeanShift.o: In function `MeanShift::segmentUsingRGB(cv::Mat, unsigned int)': /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:121: undefined reference to `cv::normalize(cv::_InputArray const&, cv::_InputOutputArray const&, double, double, int, int, cv::_InputArray const&)' MeanShift.o: In function `MeanShift::segmentFromFeatureSpace(cv::Mat const&, unsigned int, std::vector > const&, std::vector, std::allocator > >, std::allocator, std::allocator > > > > const&)': /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:145: undefined reference to `cv::split(cv::Mat const&, cv::Mat*)' MeanShift.o: In function `MeanShift::getChannelsRanges(cv::Mat, int*, SImgDims&)': /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:204: undefined reference to `cv::split(cv::Mat const&, cv::Mat*)' MeanShift.o: In function `MeanShift::getChannelsRanges(cv::Mat, int*, SImgDims&)': /usr/include/opencv2/core.hpp:819: undefined reference to `cv::noArray()' MeanShift.o: In function `MeanShift::getChannelsRanges(cv::Mat, int*, SImgDims&)': /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:214: undefined reference to `cv::minMaxLoc(cv::_InputArray const&, double*, double*, cv::Point_*, cv::Point_*, cv::_InputArray const&)' MeanShift.o: In function `MeanShift::showImage(cv::Mat, std::__cxx11::basic_string, std::allocator > const&)': /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:789: undefined reference to `cv::namedWindow(cv::String const&, int)' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:795: undefined reference to `cv::imshow(cv::String const&, cv::_InputArray const&)' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:797: undefined reference to `cv::waitKey(int)' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:800: undefined reference to `cv::destroyWindow(cv::String const&)' MeanShift.o: In function `MeanShift::makeIt8bit(cv::Mat)': /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:811: undefined reference to `cv::Mat::convertTo(cv::_OutputArray const&, int, double, double) const' MeanShift.o: In function `MeanShift::standardization(cv::Mat const&)': /usr/include/opencv2/core.hpp:819: undefined reference to `cv::noArray()' MeanShift.o: In function `MeanShift::standardization(cv::Mat const&)': /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:827: undefined reference to `cv::minMaxLoc(cv::_InputArray const&, double*, double*, cv::Point_*, cv::Point_*, cv::_InputArray const&)' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:829: undefined reference to `cv::operator-(cv::Mat const&, cv::Scalar_ const&)' /home/kvasir/Documents/PolytechSchoolWork/2018 Spring (algorithms, software engineering, computer vision, artificial intelligence, computer architecture and organization)/computer-vision/projects/3rd-assignment/MeanShift/MeanShift.cpp:829: undefined reference to `cv::operator*(cv::MatExpr const&, double)' MeanShift.o: In function `cv::Mat::Mat(int, int const*, int)': /usr/include/opencv2/core/mat.inl.hpp:446: undefined reference to `cv::Mat::create(int, int const*, int)' MeanShift.o: In function `cv::Mat::Mat(int, int const*, int, cv::Scalar_ const&)': /usr/include/opencv2/core/mat.inl.hpp:454: undefined reference to `cv::Mat::create(int, int const*, int)' /usr/include/opencv2/core/mat.inl.hpp:455: undefined reference to `cv::Mat::operator=(cv::Scalar_ const&)' MeanShift.o: In function `cv::Mat::create(int, int, int)': /usr/include/opencv2/core/mat.inl.hpp:796: undefined reference to `cv::Mat::create(int, int const*, int)' collect2: error: ld returned 1 exit status make: *** [makefile:6: segmentation] Error 1 What particularly strikes me odd about this output is that the *.o files look in /usr/include/opencv2 for function definitions, it seems. If it was called with $opencv2, shouldn't it look in /home/kvasir/separate-libs/opencv2/release/installed/*? The makefile that produces the above error is shown below: segmentation : main.cpp Loader.o MeanShift.o ControlParameters.h defs.h g++ -g -o segmentation main.cpp Loader.o MeanShift.o $(opencv2) Loader.o : Loader.cpp Loader.h g++ -g -c Loader.cpp MeanShift.o : MeanShift.cpp MeanShift.h g++ -g -c MeanShift.cpp clean: rm segmentation *.o I also tried compiling the object files with the OpenCV 2 version to no avail. My next move will probably be to reinstall OpenCV 2. However, I'm curious as to why this happened in the first place and if there's any way to fix and prevent this from happening in the future. Additionally, both of these programs successfully compile with OpenCV 3 without issue. For example, changing $(opencv2) in my makefile above to $(opencv3) results in no errors and a working program. Edit: I'm a college student and these programs are assignments for a Computer Science course. The more complicated program mentioned above was not written by me. It was provided by my professor and borrowed from another university. I have to modify it, but it is in a compile-able state as is with the one exception of main in main.cpp being void. I changed this to int and made the return statement return 0;, and it seemed to compile perfectly fine with OpenCV 3. **Note:** I know the code for both of these programs works. I'm not asking for help with coding, but I'm asking why an update to the OpenCV 3 installation in /usr/include/ would muck up a custom installation of OpenCV 2 in a separate location. Edit: Here is a link to the more complicated (image segmentation) program. Edit: I've uploaded the simpler program's source code to Google Drive. It is available here .

I've been having a harrowing time lately just trying to get several C programs compiled because I can't find where the libraries are located and pkg-config seems to be out of order. I installed GNU GSL like this: wget ftp://ftp.gnu.org/gnu/gsl/gsl-1.15.tar.gz tar xvzf gsl-*gz cd gsl-1.15 ./configure make sudo make install Apparently it installed in /usr/local/lib which is a non-standard place? (1) What is a standard place? (2) How would I get it to install there? And I can't manage to compile a simple program that uses this library: $ gcc gsl_erf.c -o gsl -I/usr/local/lib -L/usr/local/lib /tmp/cc3WD9Zq.o: In function `main': gsl_erf.c:(.text+0x24): undefined reference to `gsl_cdf_gaussian_P' collect2: error: ld returned 1 exit status Now, with pkg-config : pkg-config --libs --cflags gslPackage gsl was not found in the pkg-config search path. Perhaps you should add the directory containing `gsl.pc' to the PKG_CONFIG_PATH environment variable No package 'gsl' found So I did add the directory: PKG_CONFIG_PATH=/usr/local/lib/pkgconfig But no luck yet! :( pkg-config still gives me the same message as above. (Perhaps you sh ...) This is a more general problem I face regularly when I have to compile some C program. I would love a general solution for: 1. Where and how do I install my C libs? (Perhaps the same place yum installs them?) 2. How do I correct/configure and use pkg-config ---- **Update** : I tried one of the answer's suggestions below and running the compiled program gives me this : ./gsl_app: error while loading shared libraries: libgsl.so.0: cannot open shared object