I've used linuxbrew to install gcc 5.3 on a machine on which I don't have sudo access. I now want to link with X11:
> gcc test.c -lX11
ld: cannot find -lX11
I've checked that libX11.so exists in /usr/lib64/ which is on the compiler's LIBRARY_PATH. If I use the system's gcc it works fine, but I need a newer version to compile my actual program.
use -L flag, like this -L/usr/lib64, or you can specify full path to library like this gcc test.c /usr/lib64/libX11.so
According to this comment by a linuxbrew developer,
linuxbrewed gcc removes /usr/lib64 from the library path because mixing system libraries with brewed libraries creates havoc.
The solution is to brew install linuxbrew/xorg/xorg.
Related
I'm running a Debian (Buster) container and my goal is to compile a small program I wrote which relies on libgit2. First, I was installing libgit2 via the libgit2-dev package and my Makefile had the following:
gcc -O2 -fpic -shared -I /usr/local/include -lgit2 -o output.so my_app.c
However, I'd rather have a "cleaner" environment and install libgit2 via the libgit-27 which, AFAIK, only installs the shared object binary instead of also including the development files like libgit2-dev does.
Using find I can find where the .so file is installed into:
$ find / -name "*git2*" -print 2>/dev/null
/usr/lib/x86_64-linux-gnu/libgit2.so.0.27.7
/usr/lib/x86_64-linux-gnu/libgit2.so.27
/usr/share/doc/libgit2-27
/var/lib/dpkg/info/libgit2-27:amd64.list
/var/lib/dpkg/info/libgit2-27:amd64.symbols
/var/lib/dpkg/info/libgit2-27:amd64.md5sums
/var/lib/dpkg/info/libgit2-27:amd64.shlibs
/var/lib/dpkg/info/libgit2-27:amd64.triggers
and I've been trying several combinations of linking this .so with gcc like:
gcc -O2 -fpic -shared -L /usr/lib/x86_64-linux-gnu/ -libgit2.so.27 -o output.so my_app.c
but so far I always get the following error:
my_app.c:1:10: fatal error: git2.h: No such file or directory
#include <git2.h>
^~~~~~~~
compilation terminated.
I understand this is a glaring lack of knowledge on how C compilation works. My two questions are:
Is it possible to compile my program by just relying on the libgit2-27 Debian Buster package instead of libgit2-dev? If not, why?
If yes, an example and explanation would be appreciated!
I want to learn OpenGL programming with GLFW library. But I have problem when compiling the program. I followed tutorial on http://www.glfw.org/docs/latest/quick.html and copied the full program. I download the 64-bit version library on http://www.glfw.org/download.html.
I changed the first line from include <GLFW/glfw3.h> to include "GLFW/glfw3.h". I've put the GLFW folder inside the folder along with glfw3.dll, glfw3dll, and libglfw3.a
I'm running on Windows 7. This is my gcc version
gcc --version
gcc (tdm64-1) 5.1.0
I use this command for compiling
gcc test.c -Llib-mingw/ -lglfw3 -lopengl32 -lgdi32
But I got this error
cannot find -lglfw3
What should I do to make it work?
If you are still having problems with this compilation/linking problem, try set the glfw full lib folder path in gcc or g++ lib path with -L parameter, as simplified below. Double quotes and non-relative paths should work.
g++ "-L<path_to_glfw>\\glfw\\lib-mingw" -o <executable>.exe <.o files list> -lopengl32 -lglfw3 -lgdi32
Two notes:
There is no need to pass .a extension. MinGW g++/gcc compiler will automatically understand filename.
If you are using the 64-bit version of glfw, switch -L parameter to \glfw\lib-mingw64 (or respective 64-bit library location folder)
I am working on a program which uses ncurses which will be used on embedded systems. Since these systems won't have ncurses installed I need to statically link the library. However if I try to build it like this
gcc -static ncurs.c -o ncurs -l:libncurses.a
or
gcc -static ncurs.c -o ncurs -lncurses
I get a ton of errors like this:
(.text+0x48): undefined reference to `SP'
/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../x86_64-linux-gnu/libncurses.a(lib_slktouch.o): In function `slk_touch':
normal compilation works fine.
I have searched for hours but I can't find any good information...
platform of development is stripped down debian system.
I guess you may need additional library, can you try -lncurses -ltinfo.
You can check on your system what the linker library flags for ncurses using command
pkg-config --static --libs ncurses
on my system, I got
-lncurses -ltinfo
try adding -ltinfo to the end of your commandline
This might be the most newbie question ever, but how do you compile a C program?
I’ve downloaded the source of a C program (ffmpeg, to be precise). How do I compile it?
For most Unix-style C programs, the incantation is:
./configure
make
sudo make install
This should already be documented in the INSTALL file, which additionally may contain further useful information.
For a single file just cc file.c (or gcc or whatever you C compiler is called)
For a complex project like ffmpeg, then either make, cmake, configure some other. Check their documentation
It depends on what OS and compilers you have, but typically the sequence is:
$ ./configure
$ make
$ sudo make install
to compile simple math program, it's not enough to <include math.h>. See
gcc file.c -lmath -o program_bin
for a single .c file using ffmpeg libraries, it can be made this way:
gcc -Wall -g live_segmenter.c -o live_segmenter -lavformat -lavcodec -lavutil -lbz2 -lm -lz -lfaac -lmp3lame -lx264 -lfaad -lpthread -I/home/devicer/ffmpeg/include -L/home/devicer/ffmpeg/lib
notice -L and -I options. In serious projects they are usually set by pkg-config.
for the ffmpeg itself..
- install lame, few other required libraries, then do as Chris said.
Btw, sometimes it requires gmake, not make.
Also, have a look on
./configure --prefix /home/devicer/ffmpeg
This is what was mentioned (used for) in segmenter compilation above.
When I compile a simple Hello World! program that uses the sscanf function on my local Debian lenny x64, it works. But when I upload the same program to the server running CentOS x86, it will not work. If I do not use sscanf, then the program works on both computers.
gcc -std=c99 -O2 -pipe -m32
If I compile it with sscanf but without -std=c99, then it works on both computers.
gcc -O2 -pipe -m32
What is the problem with sscanf and c99 on CentOS x86 ? I thought that compiling with the -m32 flag would work on all Linuxes ? (I have limited access to the CentOS server, so I do not have access to error messages.)
Probably the CentOS box is using an old version of glibc. Since the nonstandard GNU extensions to their scanf implementation ended up making glibc conflict with c99, they added a nasty hack of redirecting *scanf to __isoc99_*scanf when -std=c99 is in use; if your copy of glibc is missing the __isoc99_sscanf symbol, the program will then fail to run.
Static linking, or linking to a different libc without ugly backwardsness-compatibility hacks, would solve the problem.
Are you uploading the binary or the source and then recompiling? If you are uploading the binary, you are probably running into a library compatibility issue between Debian and CentOS.
If that is the case, upload the source only and recompile on CentOS.
If you do not have permission to compile # CentOS, then try compiling a static binary. You can use dietlibc which makes smaller binaries than glibc or try EGLIBC which is the default C library that Debian will use starting Debian "squeeze".
I came up with the similar problem, it works # Ubuntu 64-bit, but the compile fails # CenseOS 64-bit (REHL5 desktop):
the error message is:
undefined reference to `__isoc99_sscanf#GLIBC_2.7'
when i copied the executable file compiled #Ubuntu to REHL5, and run it another error appeared:
elf file os abi invalid
it is compiled without flag -std=c99, i'm a newbie at C, and looking forword some workarounds, ex. add some flag.
Makefile:
CC=gcc
CCFLAGS= -Wall -O2 -DLINUX -I../include
demos:linuxdemo.c
$(CC) $(CCFLAGS) -o demoA linuxdemo.c -L../lib -lsense4 -lusb
$(CC) $(CCFLAGS) -o demoSO linuxdemo.c -lusb -lsense4
clean:
rm -f demoA
rm -f demoSO
You need to update your glibc to 2.7
download the rpm package from here:
http://archive.fedoraproject.org/pub/archive/fedora/linux/releases/8/Everything/x86_64/os/Packages/
needs:
libc-common-2.7-2.x86_64.rpm
glibc-headers-2.7-2.x86_64.rpm
glibc-devel-2.7-2.x86_64.rpm
glibc-2.7-2.x86_64.rpm
command:
rpm -Uvh --aid --nodeps glibc-common-2.7-2.x86_64.rpm
rpm -Uvh --aid --nodeps glibc-headers-2.7-2.x86_64.rpm
rpm -Uvh --aid --nodeps glibc-devel-2.7-2.x86_64.rpm
rpm -Uvh --aid --nodeps glibc-2.7-2.x86_64.rpm