I am trying to compile test.c as described this NanoPi Neo guide. However, when ever I try to run the gcc command to compile, I get this error message...
GNU ld (GNU Binutils for Ubuntu) 2.26.1
Supported emulations:
armelf_linux_eabi
armelfb_linux_eabi
/usr/lib/gcc/arm-linux-gnueabihf/5/../../../arm-linux-gnueabihf/crt1.o: In function `_start':
(.text+0x28): undefined reference to `main'
collect2: error: ld returned 1 exit status
...the command...
sudo gcc -Wall -o test.c -lwiringPi -lpthread -Wl,-V
...and the code I'm trying to compile...
#include <wiringPi.h>
int main(void)
{
wiringPiSetup() ;
pinMode (7, OUTPUT) ;
for(;;)
{
digitalWrite(7, HIGH) ;
delay (500) ;
digitalWrite(7, LOW) ;
delay (500) ;
}
}
May I guess that this is a possible linking issue? I'm just not sure and I really do know how to change it.
I am rather novice-like when it comes to topics like C, Linux and the like. :)
You have not specified any .c source files since the -o specifies the output as #user3386109 mentioned.
sudo gcc -Wall test.c -o output_file_name -lwiringPi -lpthread -Wl,-V
Related
I'm a beginner to learn the basic compiling. I create a very simple c file as below
#include <stdio.h>
int main (void) {
printf("Hello World!\n");
return 0;
}
then I run the commands,
cpp -E helloworld.c -o helloworld.i
gcc -S helloworld.i -o helloworld.s
as helloworld.s -o helloworld.o
ld -shared -o helloworld /usr/lib64/libc.so helloworld.o
in here, I got an error message like this,
ld -shared -o helloworld /usr/lib64/libc.so helloworld.o
ld: helloworld.o: relocation R_X86_64_32 against `.rodata' can not be used when making a shared object; recompile with -fPIC
ld: final link failed: Nonrepresentable section on output
so I rerun the upper but with a -fPIC
cpp -E helloworld.c -o helloworld.i
gcc -S helloworld.i -o helloworld.s -fPIC
as helloworld.s -o helloworld.o
ld -shared -o helloworld /usr/lib64/libc.so helloworld.o
at last, I got my helloworld, but when I try ./helloworld, I got a Segmentation fault.
anyone can help? Thanks in advance!
I try the gcc helloworld.c -Wl,--verbose | grep succeeded and get some output as below,
attempt to open /usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/crt1.o succeeded
attempt to open /usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/crti.o succeeded
attempt to open /usr/lib/gcc/x86_64-redhat-linux/4.8.5/crtbegin.o succeeded
attempt to open /tmp/ccSuIvy2.o succeeded
attempt to open /usr/lib/gcc/x86_64-redhat-linux/4.8.5/libgcc.a succeeded
attempt to open /usr/lib/gcc/x86_64-redhat-linux/4.8.5/libgcc_s.so succeeded
attempt to open /usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/libc.so succeeded
attempt to open /lib64/libc.so.6 succeeded
attempt to open /usr/lib64/libc_nonshared.a succeeded
attempt to open /lib64/ld-linux-x86-64.so.2 succeeded
attempt to open /usr/lib/gcc/x86_64-redhat-linux/4.8.5/libgcc.a succeeded
attempt to open /usr/lib/gcc/x86_64-redhat-linux/4.8.5/libgcc_s.so succeeded
attempt to open /usr/lib/gcc/x86_64-redhat-linux/4.8.5/crtend.o succeeded
attempt to open /usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/crtn.o succeeded
but I still don't know how to do the link, I try this one
ld -shared -o helloworld /usr/lib64/libc.so /usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/crti.o /usr/lib/gcc/x86_64-redhat-linux/4.8.5/libgcc_s.so /usr/lib/gcc/x86_64-redhat-linux/4.8.5/crtend.o /usr/lib64/crtn.o helloworld.o /usr/lib/gcc/x86_64-redhat-linux/4.8.5/libgcc.a /usr/lib64/libc_nonshared.a /usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/crt1.o
but get an error message,
ld: /usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/crt1.o: relocation R_X86_64_32S against undefined symbol `__libc_csu_fini' can not be used when making a shared object; recompile with -fPIC
ld: final link failed: Nonrepresentable section on output
My File name is hello.c
#include<stdio.h>
int main(void)
{
printf("Hello World!");
return 0;
}
and the commands I gave are:
$ gcc hello.c -o hello
$ gcc ./hello
The Terminal output is:
/usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
collect2: error: ld returned 1 exit status
Can please Anyone help me?
I use:
gcc version 7.2.0 (Debian 7.2.0-20)
$ gcc hello.c -o hello
$ gcc ./hello
Assuming you were trying to run it with that second command, it should just be ./hello (in other words, get rid of the gcc at the start).
What you're trying to do is compile/link the executable file that you've already compiled from source, when it's already in a state where it can be run.
I am creating an exe and shared library in cygwin.
The library is created and is in the proper place, but when I try to compile the client code daemon, the linking phase says that it can't find the sysutil library.
Error is posted below:
/usr/lib/gcc/i686-pc-cygwin/5.4.0/../../../../i686-pc-cygwin/bin/ld: cannot find -lsysutil
collect2: error: ld returned 1 exit status
make: *** [Makefile:84: daemon] Error 1
I tried exporting the path using LD_LIBRARY_PATH but unfortunately that also didn't help.
daemon.c
#include <stdio.h>
#include <sys_util.h>
int main(){
sys_util();
while(1){
}
return 0;
}
sysutil.c
#include <stdio.h>
#include "sys_util.h"
int sys_util(){
return 0;
}
sysutil.h
int sys_util();
test.bat
g++ -fpic -c sysutil.c
g++ -shared -o libsysutil.so sysutil.o -I.
g++ -c daemon.c -I.
g++ -o daemon.exe daemon.o -L. -lsysutil
del *.o
Shared library is generated sysutil.so in the folder c:/test same as the source code (daemon.c,sysutil.c,sys_util.h,test.bat,libsysutil.so)
Cygwin console output:
/cygdrive/c/test
$ ./test.bat
C:\test>g++ -fpic -c sysutil.c
sysutil.c:1:0: warning: -fpic ignored for target (all code is position independent)
C:\test>g++ -shared -o libsysutil.so sysutil.o -I.
C:\test>g++ -c daemon.c -I.
C:\test>g++ -o daemon.exe daemon.o -L. -lsysutil
c:/mingw/bin/../lib/gcc/mingw32/5.3.0/../../../../mingw32/bin/ld.exe: cannot find -lsysutil
collect2.exe: error: ld returned 1 exit status
C:\test>del *.o
Cygwin expects shared libraries to have the .dll extension.
Change the second line in your batch file to:
g++ -shared -o sysutil.dll sysutil.o -I.
See the users' guide for more info:
https://cygwin.com/cygwin-ug-net/dll.html
I have a problem with my QTCreator-generated Makefile. Everything is working fine except when I try to create myself a new executable file for my tests, my terminal says: bash: ./RunTests: cannot execute binary file: Exec format error
Here is how my MakeFile rule looks like:
TESTS: ../WannaBeRPG/testes.cpp ../WannaBeRPG/hero.h ../WannaBeRPG/charinterface.h
$(CXX) -c $(CXXFLAGS) $(INCPATH) -o RunTests ../WannaBeRPG/testes.cpp
Flags are:
CXX = g++
CXXFLAGS = -pipe -g -std=gnu++0x -Wall -W -fPIC $(DEFINES)
INCPATH = -I../WannaBeRPG -I. -I/usr/lib64/qt5/mkspecs/linux-g++
DEFINES = -DQT_QML_DEBUG
If that is anyhow helpful here is my testes.cpp file:
#include <gtest/gtest.h>
#include "hero.h"
TEST(teee, HPTEST)
{
Hero myHero("Hika",150,100,0,0,0,0,0,0,0);
EXPECT_EQ(100,myHero.getHP());
}
int main_tests(int argc, char* argv[])
{
testing::InitGoogleTest(&argc,argv);
return RUN_ALL_TESTS();
}
I am using Fedora.
Any ideas why does this works this way? Primary exec from this Makefile works completely fine.
The -c argument to g++ tells it not to link your binary. Thus, your output file is an object file rather than an executable.
I'm trying to compile a CUDA program in Linux and I get the following linker error:
/usr/lib/gcc/x86_64-redhat-linux/4.4.4/../../../../lib64/crt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
collect2: ld returned 1 exit status
This is my Makefile:
mtrand.o : mtrand/mtrand.cpp
nvcc -I"./mtrand" -O2 -c mtrand/mtrand.cpp
CUDAMCMLrng.o : CUDAMCMLrng.cu
nvcc --use_fast_math -O2 -c CUDAMCMLrng.cu
kernel.o : CUDAMCMLrng.o kernel.cu
nvcc --use_fast_math -O2 -c kernel.cu
main.o : mtrand.o CUDAMCMLrng.o kernel.o main.cu
nvcc --use_fast_math -O2 -Xcompiler "-fopenmp -Wall" -c main.cu
lab : main.o mtrand.o CUDAMCMLrng.o kernel.o
nvcc -lgomp -o lab main.o mtrand.o CUDAMCMLrng.o kernel.o
The main function is in the main.cu file but for some reason the linker is not seeing it.
Could anyone please tell me what am I doing wrong?
Thanks!
I recommend doing the final linking with g++ rather than nvcc. If you only have .o files and libraries as input to the link line, I see no reason to use nvcc.