I have taken my first two courses in java and now have to take Data Structures in C++. I'm trying to open up the different files I've compiled.
They're just two "Hello, world!" programs with slightly different text.
When I type:
g++ HelloWorld.cpp
The file "a.out" is created which I run by typing ./a.out into the command prompt.
Now that I compiled a second executable program, HelloWorldII.cpp, the a.out file only runs that program.
When I try to run ./HelloWorld.cpp I got permission denied, so I typed in:
sudo chmod 744 /Users/username/HelloWorld
to make me the owner of the folder which didn't work so I typed in:
sudo chown -R "$garyjones:" users/username/HelloWorld
to give the owner(me) permission to edit/open, after which when I attempted to run ./HelloWorld.cpp, terminal began to attempt executing it but instead showed me syntax error even though compiling them with g++ HelloWorld.cpp and running them with their a.out files worked fine.
If I have multiple executable files in a folder, how can I open the one I want?
When you compile and link code, the executable is by default named a.out - you are supposed to add a parameter to the linking to name it.
If you don’t do it, they are all going to be named a.out, and of course overwrite each other - there can be only one file with that name.
It is strange for you attempting to execute a pure ascii text file. You don't understand the execution mode's meaning. You are not familiar with g++. It seems like you don't know the process of how an executable file generated by compiler from source file.
And here is my advice.
Google the basic usage of g++ or some other compilers. Choose your favourite.
Here is the temporary solution.
g++ <source file> -o <executable filename>
Example:
## if you don't specific a name for the binary file,
## it will generate a.out and delete the exiting a.out firstly
g++ HelloWorld.cpp -o HelloWorld
## and then you can execute it
./HelloWorld
Figure out what the exact meaning of file permission.
The a.out filename has traditional reason and I recommend you to explore it. It's funny.
I'm repeatedly experiencing problems with libraries which are not found.
In my bashrc I have:
LD_LIBRARY_PATH=
LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/lib1
LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/lib2
LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/lib3
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH
These paths contain ALL folders from where I link libraries into my program with -L/lib1 -l1a -L/lib2 -l2a -L/lib3 -l3a.
Now I start my program standalone:
./program
Fine!
Then I start it with mpiexec from mpich:
/mpich/intel/bin/mpiexec -np 2 ./solvertest1
Fine!
BUT THEN I start it with gdb enabled:
/mpich/intel/bin/mpiexec -np 2 gdb ./solvertest1
Problem, libraries are not found:
Starting program: /my/program
/my/program: error while loading shared libraries: libirng.so: cannot open shared object file: No such file or directory
I suspect that there's something wrong when the LD_LIBRARY_PATH should be propagated through all the subprocesses and shells those scripts and programs produce... What do I have to do to let every subprocess (and whatever else will be started) know where those libraries are?
Store the library path in the DT_RPATH tag of your executable when linking
-Wl,rpath=/lib1 -Wl,rpath=/lib2 -Wl,rpath=/lib3
that way you don't need to mess with LD_LIBRARY_PATH and shell initialization.
Since the program is dependent on having the right environment variables set to run, and mpiexec isn't giving it the env it needs, try something like these from the mpiexec docs:
-x , --envall
Export all environment variables to all processes.
-E , --env name value
Export the variable name with the content value.
I want to create one unix command, which will unzip the folder.
so, I am searching for the code, but I am not aware that how should I use such code to make Unix command?
I have gone through various questions & answers but I don't get any perfect information.
So, can any one please suggest me any code (in C++ or C or any language to make exe) and to use it as a Unix command.
NOTE: I know command like 'unzip' is available in 'Mks toolkit' type of software but we can not use it, so I want to make command which can run through 'command prompt'
If you want to add a command, you only need to create your executable and put its link in the /usr/bin folder.
Just compile your code and set a link to it's executable like this:
ln -s /path/to/your_executable /usr/bin/command_name
If there exists a command that you need to modify, you should set an alias to it. For example, you want ls -1 to run whenever ls is used, then you only need to use the command:
alias ls=ls -1
or put the same command in the .bashrc file in your home directory.
I have a program which requires liblog4cpp installed to run.
Now, I want the program to run on another machine without liblog4cpp. So I just find the log4cpp.so and move it to the same directory of my program. But at running error reported:
error while loading shared libraries: liblog4cpp.so.4: cannot open
shared object file: No such file or directory
Am I doing it right? How can I tell the program to find the SO file just beside it?
In addition to what others are suggesting, consider adding the file to the dynamic linker's cache. You can do it like this:
ldconfig -l /path/to/lib/liblog4.so.4
To add it to the loader's cache use the following command: ldconfig
Then in order to verify that it was correctly added, run this:
ldconfig -v | grep liblog
Check your LD_LIBRARY_PATH environment variable... One of the directories on the path should point to the location of your log4cpp.so file; also the linux command ldd is handy for determining which shared object libraries are being used in your executable. The syntax is ldd <executable>.
assuming that the path where the .so file/s is available is /path you can also avoid to export an environment variable and just use
LD_LIBRARY_PATH=/path ./myProgram
beware the fact that if you do:
export LD_LIBRARY_PATH=/path
you are resetting LD_LIBRARY_PATH to a single value /path and losing anything you added before to this environment variable. If you want to add a value without losing the previous ones
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/path
export LD_LIBRARY_PATH to the path of the library. This env variable works much like the PATH variable. It can contain multiple paths separated by :.
In the rc script from where you are launching your program, you should set the LD_LIBRARAY_PATH before launching the application. Remember, the .so are the shared libraries, it is required at the run time to link. Thus, it should be available in the standard path like /usr/lib before launching.
In case it is not copied in the standard path like /usr/lib then specify the path by using the following.
export LD_LIBRARY_PATH=<new_path_of_so>:$(LD_LIBRARY_PATH)
Ideally, I would have placed this .so in the standard path like /usr/lib. If it is installed in the standard path, then there is no need to set the above path. Remember, to make your program better, put the new path in ldconfig.conf.
You can debug such errors by using the following.
$strace <binary_name>
to know the so dependencies
$ldd <binary_name>
For further, check the below link.
http://www.tune2wizard.com/sharedobject-crash/
After adding shared objects (or shared libraries lib*.so*, or such symbolic links) to system directories like /usr/lib or /lib known to the dynamic linker ld-linux.so(8) (or ld.so) you need to run ldconfig(8)
You could also add them to /usr/local/lib/ but then be sure that /etc/ld.so.conf (or some file /etc/ld.so.conf.d/*.conf) .mentions that directory (and run ldconfig after changing it)
How can I compile/run C or C++ code in a Unix console or a Mac terminal?
If it is a simple single-source program,
make foo
where the source file is foo.c, foo.cpp, etc., you don’t even need a makefile. Make has enough built-in rules to build your source file into an executable of the same name, minus the extension.
Running the executable just built is the same as running any program - but you will most often need to specify the path to the executable as the shell will only search what is in $PATH to find executables, and most often that does not include the current directory (.).
So to run the built executable foo:
./foo
gcc main.cpp -o main.out
./main.out
This is the command that works on all Unix machines... I use it on Linux/Ubuntu, but it works in OS X as well. Type the following command in Terminal.app.
g++ -o lab21 iterative.cpp
-o is the letter O, not zero
lab21 will be your executable file
iterative.cpp is your C++ file
After you run that command, type the following in the terminal to run your program:
./lab21
Two steps for me:
First:
make foo
Then:
./foo
All application execution in a Unix (Linux, Mac OS X, AIX, etc.) environment depends on the executable search path.
You can display this path in the terminal with this command:
echo $PATH
On Mac OS X (by default) this will display the following colon separated search path:
/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin
So any executable in the listed directories can by run just by typing in their name. For example:
cat mytextfile.txt
This runs /bin/cat and displays mytextfile.txt to the terminal.
To run any other command that is not in the executable search path requires that you qualify the path to the executable. So say I had an executable called MyProgram in my home directory on Mac OS X I can fully qualify it like so:
/Users/oliver/MyProgram
If you are in a location that is near the program you wished to execute you can qualify the name with a partial path. For example, if MyProgram was in the directory /Users/oliver/MyProject I and I was in my home directory I can qualify the executable name like this, and have it execute:
MyProject/MyProgram
Or say I was in the directory /Users/oliver/MyProject2 and I wanted to execute /Users/oliver/MyProject/MyProgram I can use a relative path like this, to execute it:
../MyProject/MyProgram
Similarly if I am in the same directory as MyProgram I need to use a "current directory" relative path. The current directory you are in is the period character followed by a slash. For example:
./MyProgram
To determine which directory you are currently in use the pwd command.
If you are commonly putting programs in a place on your hard disk that you wish to run without having to qualify their names. For example, if you have a "bin" directory in your home directory for regularly used shell scripts of other programs it may be wise to alter your executable search path.
This can be does easily by either creating or editing the existing .bash_profile file in your home directory and adding the lines:
#!/bin/sh
export PATH=$PATH:~/bin
Here the tilde (~) character is being used as a shortcut for /Users/oliver. Also note that the hash bang (#!) line needs to be the first line of the file (if it doesn't already exist). Note also that this technique requires that your login shell be bash (the default on Mac OS X and most Linux distributions). Also note that if you want your programs installed in ~/bin to be used in preference to system executables your should reorder the export statement as follows:
export PATH=~/bin:$PATH
Do all of this in "Terminal".
To use the G++ compiler, you need to do this:
Navigate to the directory in which you stored the *.cpp file.
cd ~/programs/myprograms/
(the ~ is a shortcut for your home, i.e. /Users/Ryan/programs/myprograms/, replace with the location you actually used.)
Compile it
g++ input.cpp -o output.bin (output.bin can be anything with any extension, really. Extension .bin is just common on Unix.)
There should be nothing returned if it was successful, and that is okay. Generally you get returns on failures.
However, if you type ls, you will see the list of files in the same directory. For example, you would see the other folders, input.cpp and output.bin
From inside the directory, now execute it with ./outbut.bin
A compact way to go about doing that could be:
make foo && ./$_
It is nice to have a one-liner so you can just rerun your executable again easily.
Assuming the current directory is not in the path, the syntax is ./[name of the program].
For example ./a.out
To compile C or C++ programs, there is a common command:
make filename
./filename
make will build your source file into an executable file with the same name. But if you want to use the standard way, You could use the gcc compiler to build C programs and g++ for C++.
For C:
gcc filename.c
./a.out
For C++:
g++ filename.cpp
./a.out
Add the following to get the best warnings, and you will not regret it. If you can, compile using WISE (warning is error).
- Wall -pedantic -Weffc++ -Werror
Step 1 - create a cpp file using the command
touch test.cpp
Step 2 - Run this command
g++ test.cpp
Step 3 - Run your cpp file
./a.out
I am on a new MacBook Pro with the Apple M1 Pro chip. I have my Xcode installed - both IDE and command line tools. This is how it worked for me:
g++ one.cpp -o one
./one
Use a makefile. Even for very small (= one-file) projects, the effort is probably worth it because you can have several sets of compiler settings to test things. Debugging and deployment works much easier this way.
Read the make manual. It seems quite long at first glance, but most sections you can just skim over. All in all, it took me a few hours and made me much more productive.
I found this link with directions:
http://www.wesg.ca/2007/11/how-to-write-and-compile-c-programs-on-mac-os-x/
Basically you do:
gcc hello.c
./a.out (or with the output file of the first command)
In order to compile and run C++ source code from a Mac terminal, one needs to do the following:
If the path of .cpp file is somePath/fileName.cpp, first go the directory with path somePath
To compile fileName.cpp, type c++ fileName.cpp -o fileName
To run the program, type ./fileName
Just enter in the directory in which your .c/.cpp file is.
For compiling and running C code.
gcc filename.c
./a.out filename.c
For compiling and running C++ code.
g++ filename.cpp
./a.out filename.cpp
You need to go into the folder where you have saved your file.
To compile the code: gcc fileName
You can also use the g++ fileName
This will compile your code and create a binary.
Now look for the binary in the same folder and run it.
For running C++ files, run the below command, assuming the file name is "main.cpp".
Compile to make an object file from C++ file.
g++ -c main.cpp -o main.o
Since #include <conio.h> is not supported on macOS, we should use its alternative which is supported on Mac. That is #include <curses.h>. Now the object file needs to be converted to an executable file. To use file curses.h, we have to use library -lcurses.
g++ -o main main.o -lcurses
Now run the executable.
./main
Running a .C file using the terminal is a two-step process.
The first step is to type gcc in the terminal and drop the .C file to the terminal, and then press Enter:
gcc /Desktop/test.c
In the second step, run the following command:
~/a.out