I'm on a Mac and in terminal I'm compiling my program
gcc -Wall -g -o example example.c
it compiles (there are no errors), but when I try to provide command line arguments
example 5 hello how are you
terminal responds with "-bash: example: command not found"
how am supposed to provide the arguments I want to provide after compiling?
Run it like this with path:
./example 5 hello how are you
Unless the directory where the example binary is part of the PATH variable, what you have won't work even if the binary you are running is in the current directory.
It is not a compilation issue, but an issue with your shell. The current directory is not in your PATH (look with echo $PATH and use which to find out how the shell uses it for some particular program, e.g. which gcc).
I suggest testing your program with an explicit file path for the program like
./example 5 hello how are you
You could perhaps edit your ~/.bashrc to add . at the end of your PATH. There are pro and conses (in particular some possible security issues if your current directory happens to be sometimes a "malicious" one like perhaps /tmp might be : bad guys might put there a gcc which is a symlink to /bin/rm so you need to add . at the end of your PATH if you do).
Don't forget to learn how to use a debugger (like gdb). This skill is essential when coding in C (or in C++). Perhaps consider also upgrading your gcc (Apple don"t like much its current GPLv3 license so don't distribute the recent one; try just gcc -v and notice that the latest released GCC is today 4.8.1).
./example 5 Hello how are you is the syntax you're looking for.
This article lends a good explanation as to why this is important.
Basically, when you hit Enter, the shell checks to see if the first set of characters is an absolute path. If it's not, it checks the PATH variable to find executables with the name of the command you are trying to run. If it's found, it will be run, but otherwise it will crash and burn and you will become very sad.
Related
I have written a c program. I want to pipe the program and I want to make it look meaningful. So instead of writing ./a.out each time, I want to name it changetext. To achieve that, I compiled my program following way: gcc -o changetext myprog.c. To the best of my knowledge, this should replace the use of ./a.out and changetext should do that instead. But I'm getting command not found. I am new to c and unix environment. Any suggestion appreciated.
As I said in a comment, you can either put a dot slash (./) in front of the executable to run it
./changetext
Or you put in in a directory that is referenced in the PATH environment variable. A nice explanation of this safety feature can be found here (thanks to rubenvb):
http://www.linfo.org/dot_slash.html
It says that this is more or less to distinguish built-in commands from user-written commands with the same name. I am not convinced though. The shell could simply prefer built-in names to user-supplied ones, and look in the current directory as well as in the PATH.
But this is the *nix way.
In order to compile and run a program such as your changetext with just the command chanhetext, you must put the binary in a directory listed in your PATH environment variable. It is recommended that you put programs that you made for your own use in the ~/bin/ directory. The command you would use to accomplish this would be the following, assuming ~/bin/ already exists:
gcc -o ~/bin/changetext myprog.c
If it does not exist, you can simply create it, then log out and back in.
If you are tired of doing the ./ before the program name you can always make an alias such as
alias a='./a.out' or alias changetext='./changetext'
this just basically look for everytime you type changetext or a and then replaces it to have the ./ infront of it
I once tried to compile a C program I made that was for a chess game (thanks to YouTube's Bluefever Software for the tutorial), but when I went to compile the program, I executed this line of code:
C:\TDM-GCC-64\>gcc Chess/chess.c Chess/init.c -o chess
The compiling worked (there were no syntax errors or anything), but when I got to my file directory, I saw this (circled in blue):
An unexpected application (but there were no viruses!):
How did this happen? It may had something to do with the line I was compiling, but what is the "intel" behind this?
It is normal for the compiler to generate an application!
What is surprising is the location for the executable, it should have been generated in the parent directory:
C:\TDM-GCC-64\> gcc Chess/chess.c Chess/init.c -o chess
The explanation is interesting:
You are using the Windows operating system, where the filenames are case insensitive.
You instructed gcc to generate the executable into chess, but this is the name of the Chess directory. In this case, gcc generates the executable in the named directory and gives it a name that is the basename of the first source file chess.c -> chess.
Furthermore, the application name really is chess.exe in Windows, but the default setting for the file manager is to not display file extensions. This is a very unfortunate choice. I suggest you change this setting in the Windows/File Explorer Options window to always show file extensions. This will allow you to distinguish chess.c, chess.exe and chess.h more easily.
You have a Makefile in the Chess directory, you should use the make command to build the executable:
C:\TDM-GCC-64\> make -C Chess
Or simply cd to the Chess subdirectory and type:
C:\TDM-GCC-64\Chess> make
That's the file you told the compiler to make.
The -o option to gcc is the output file. In this case, you told it to create an executable file named chess. And that's exactly what was created.
The compiler is automatically creating an executable file while compiling.
I'm trying to find a way to convert simple C code to NASM assembly. I have tried using objconv and downloaded and unzipped and built it since I am using a MAC; however, it doesn't seem to be working. I keep getting "-bash: objconv: command not found". Does anyone know another way or can help me solve the -bash error.
Bash is the program that takes the words you type in a terminal and launches other programs. If it is reporting an error, it is because it cannot find the program you want to run (at least in this case).
You need to either find a pre-packaged installation of objconv, or you need to do the work to "integrate" your copy of objconv yourself.
If you can identify the executable you want to run (probably called objconv) you need to add that to your path. The easiest way (if it is just for you) is to verify that your ~/.bashrc or ~/.bashprofile has a line that looks something like
PATH=$PATH:${HOME}/bin
Don't worry if it doesn't look exactly the same. Just make sure there's a ${HOME}/bin or ~/bin (~ is the short version of ${HOME}).
If you have that then type the commands
cd ~/bin
ln -fs ../path/to/objconv
and you will create a soft link (a type of file) in your home binary directory, and the program should be available to the command line.
If you create the file, and nothing above has any errors, but it is not available to the command line, you might need to set the executable bit on your "real" (not link) copy of objconv.
If this doesn't work, by now you should be well primed for a better, more specific question.
If you have gcc installed, try gcc -masm=intel -S source.c to generate assembly files in a syntax very similar to that of MASM.
I have a problem with compiling and running C codes in notepad++.
I am using the nppexec plugin and wrote the following in the script section after pressing F6:
C:\MinGW\bin\gcc.exe -g "$(FULL_CURRENT_PATH)" -o "$(CURRENT_DIRECTORY)\$(NAME_PART).exe"
$(CURRENT_DIRECTORY)\$(NAME_PART).exe
After pressing OK, I get the following on the console:
C:\MinGW\bin\gcc.exe -g "D:\Silent\Documents\College Stuff\6th sem\NETWORKING lab\substitutioncypher.C" -o "D:\Silent\Documents\College Stuff\6th sem\NETWORKING lab\substitutioncypher.exe"
Process started >>>
<<< Process finished. (Exit code 0)
D:\Silent\Documents\College Stuff\6th sem\NETWORKING lab\substitutioncypher.exe
Process started >>>
Here, substitution.c is my program to be run. The problem is that the gcc part is working fine but I am not able to execute the program from here as there is no response.
As you see, it just says process started and after that nothing. No response to a key being pressed, it just accepts everything like a text editor.
If I go to the working directory and execute the program from there (double clicking the exe file) then it seems to run perfectly fine. The problem seems to be in my script or the plugin.
Please, can anyone find out what is wrong with my compiling and running script?
In addition to #paxdiablo 's answer, you may also find useful the following NppExec script for single file projects:
npp_save
cd "$(CURRENT_DIRECTORY)"
cmd /c del "$(NAME_PART)".o "$(NAME_PART)".exe *.o
C:\MinGW\bin\gcc.exe -g3 -std=c89 -pedantic -Wall -Wextra -Wno-nonnull "$(NAME_PART)".c -o "$(NAME_PART)".exe
npp_run "$(NAME_PART)".exe
The 1st line saves the document that is currently active inside notepad++.
The 2nd line ensures your current directory is the one of the active document. This let you refraining from using the "$(CURRENT_DIRECTORY)" variable in the rest of the lines.
The 3rd line removes any executables and object-file leftovers from previous successful compilations. Removing the last executable is a nice idea, because if you don't then the last line will cause your .exe produced by the last compilation to be run anyway, even if your current compilation fails. A failed compilation does not produce an .exe, so normally you don't want NppExec to run the previous .exe. Removing the previously produced object-file is optional, but it does ensure that it will not affect fresh compilations (it makes more sense in multi-file projects, as an alternative to the touch command-line tool).
The 4th line compiles the active document. Feel free to modify gcc's options according to your needs. If you add C:\MinGW\bin into the Windows PATH environment variable, and assuming you are using only one gcc installation on your system, then you can skip the absolute path, and write just gcc instead.
The last line executes the produced executable. The npp_run command tells NppExec to launch a new command-prompt window, and run your program in it (unless it is a WIN32 GUI program). I personally find it more convenient compared to the NppExec console embed in notepad++. It looks more natural and it also avoids some I/O redirection problems of the NppExec console.
However, if your program is a console app that does not interact with the user say via a loop, then this approach will cause the launched command-prompt window to close immediately after your program terminates, not giving you the chance to inspect its output. In that case you should have you program waiting for a key to be pressed by the user just before its termination. A quick-and-dirty way is to put a system("pause"); right before your main() function's return and/or exit() statements (it is much better though to write a simple cross-platform function or macro for this).
You may experiment with the above script by typing it in F6's <temporary script> and save it permanently for general use when you are happy with its behavior.
On a side note, you may also find it useful to have a look at this post, where I'm trying to explain how to setup NppExec so it jumps to the appropriate line in the source code, by double-clicking on any error gcc spits in the NppExec console during compilation.
hello everyone
i try to debug a program, which have been installed by makefile.
it have a binary file of OpenDPI_demo.o and a shell shellscript OpenDPI_demo.
when i gdb OpenDPI_demo.o,i have a problem. i can't run it. the error is:
Starting program: /home/lx/ntop/test/opendpi/src/examples/OpenDPI_demo/OpenDPI_demo.o
/bin/bash: /home/lx/ntop/test/opendpi/src/examples/OpenDPI_demo/OpenDPI_demo.o：can't execute the binary file.
please tell me why. actually i can run the program by ./OpenDPI_demo.
thank you.
Based on the extension, the file is an object file. It is used by the linker (alongside other object files) to produce an executable. It's the real executable the one you want to run/debug.
This is another example of difficulties encountered with programs using libtool.
the file OpenDPI_demo alongside OpenDPI_demo.o is actually, as you said, a shell script which wraps the execution of the real compiled file, probably in .libs/OpenDPI_demo.
libtool needs this wrapper to adjust the runtime library paths and such so that you can execute the program transparently, as if it was actually installed on your system.
The way to correctly debug this application is not
/home/lx/ntop/test/opendpi $ gdb src/examples/OpenDPI_demo/.libs/OpenDPI_demo
but rather using libtool --mode=execute on the shell script, like the following (it's an example):
/home/lx/ntop/test/opendpi $ ./libtool --mode=execute gdb --args \
src/examples/OpenDPI_demo/OpenDPI_demo -f capture.pcap
Suggest you use
gdb OpenDPI_demo
instead
In your makefile if it depens on the object, make it depend on OpenDPI_demo, e.g.