Gdb Step The Program Is Not Being Run
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Sometimes gdb show error message "The program is not being run". This is very common error most of gdb users face.This post describes this error message and how to fix this error.What does this error mean, "The program is not being run"?This error tells, program is not running. By "not running" means program hasn't even started executing. So its not like that program has been paused in between which happens when breakpoint is hit.
When this error occurs?When such gdb command is executed, which is applicable only when program execution has been started, then gdb shows this error message notifying that gdb can't execute command because program is not running.Generally people face this error while executing continue command without starting execution of program.
How to fix this error?It is very easy to fix this error. Just start running program using run or start command, and then execute your desired command.Happy Debugging!
Most installations of the GNU c++ compiler (g++) also include the GNU debugger, GDB. This page is meant to be a guide to doing some basic debugging with GDB. Be aware that there are many other features available, this is just a basic introduction.Why use a debugger?Debuggers are useful for debugging runtime errors. Whenever a program crashes, it will print out the output up to that point and then give you an error message indicating what is wrong (e.g. "segmentation fault"). These messages are not always very helpful, as they tell you what went wrong, but not where. If your program has a lot of output, you can use that to narrow down where the error is occuring. However, that is not very useful for a program without much output.
One common strategy for debugging is to include some extra output statements throughout the code that will be removed before the final version of the code is complete. These may be simple labels (e.g. "About to enter for loop") or print out the values of variables. While this strategy often works well, especially if you have a reasonable idea of where in the code errors are likely to occur, sometimes it is not enough to quickly get to the heart of the problem. A debugger can both help speed up this process and give you a better idea of what is happening as your program is running.
Once you have compiled an executable file that includes a debugging symbol table, you debug it by opening it in gdb. This is done by running gdb using the following format:gdb program_nameSo, for example, if you wanted to debug the program "main", you would run:gdb mainAt this point, you will be at the gdb command prompt. You can do various things before running the program, but are not required to. The simplest step at this point is to just run the program using the command:runwhich will run the program exactly as if you had run it from the command line. If the program encounters a runtime error then gdb will usually print a line number, then save the state of the program at the time of the error and allow you to interact with it to get more information at the gdb prompt.
There are various commands for getting information about the current state of the program when at the gdb prompt (shortcuts will be in parentheses when appropriate):bt - prints the current function stack, indicating where you are in the current program and what function calls got you thereup (u) - moves to the next frame up in the function stack (traversing the stack is useful for getting local variables in other functions)down (d) - moves to the next frame down in the function stackframe #(f #) - moves to the stack frame numbered #print x (p x) - prints the current value of the variable x. You use the varaible names as they are referred to in the current function in the source codel - lists 10 lines of source code for the current linel # - lists 10 lines of source code surrounding a specific line (#)info locals (i locals) - prints all local variables in the current stack frameinfo args (i args) - prints the arguments of the current stack frame
When you are debugging a program, it is often useful to get the program state before it actually comes to the error. For example, if have an error because you are dereferencing a null pointer, it may help you find where the pointer gets set to null. The most common way of doing this is to set a breakpoint. When a running program in GDB encounters a breakpoint, it will immediately stop and allow you to view the program state. You can also use GDB commands at this time to continue running the program, either one line at a time or until it hits the next breakpoint/runtime error. Some of the useful commands for controlling program flow are:break # (b #) - sets a breakpoint at line number #break func (b func) - sets a breakpoint at the function called funcwatch condition/variable - pauses the program when condition/variable changes its valuedelete N (d N) - removes breakpoint number Nrun (r) - start the program. If the program is currently paused, it wil restart.continue (c) - continues the program from its current point, stopping at the next breakpoint/runtime errornext (n) - runs the next line of the program. If the line is a function call, it runs the entire function, then pausesstep (s) - runs the next instruction. This is similar to next, but if the next line is a function call, it will jump into the function and execute the first statement before pausingquit (q) - quits GDBAdditional TipsWhen you have multiple source files and you need to refer to one in particular, you use filename: before the line number. For example, to set a breakpoint at line 120 in the file other.cpp, you would use:break other.cpp:120Debugging in GDB can take a while to get used to. A good way to get comfortable is to first get used to using some of the most common.I would recommend starting with bt and print. Then look at break, next, and step. From there, you can add in more commands as you need them. For more advanced topics, including the commands not listed here, there are other tutorials on the web and you can always use GDB's help command. Also be aware that there are other ways to use GDB than just running your program directly (you can use a core dump, for example).
The COBOLworx cbl-gdb package provides source-level debugging ofCOBOL programs compiled with the GnuCOBOL compiler. Our goal here is toprovide a general understanding of how the package works, and show whatit can do.
We have, instead, developed a way to convince GDB that it isdebugging a program written in the C Programming Language. The targetexecutable, however, is altered so that the embedded debugginginformation points back to the original COBOL source code, and we havecreated an extension to GDB, written in Python, that manages the displayof COBOL variables and their contents.
The cbl-gdb extensions work by interjecting additional steps that addCOBOL variable-name identifier information into the executable, modifiesthe debugging information to point back to lines of the original COBOLsource code, and includes an instruction to load a COBOL-aware Pythonscript that extends GDB.
For anybody new to COBOL: Every COBOL program has to have anIDENTIFICATION division. The WORKING-STORAGE section is where variabledefinitions go. This program defines four variables: one 64-characteralphanumeric string, and three four-digit numeric variables.
The GnuCOBOL compiler operates by translating the COBOL source codeinto the C programming language. The GCC compiler then goes through itsnormal behavior, which is to convert the C code to assembly language(which has a .S file extension). That assembly language is then compiled(or assembled, if you prefer) into machine language, which is packagedby the loader (along with debugging information, if any) into anexecutable.
Note that for all labs, the Makefile you're provided with will automaticallycompile your program(s) for you with the -g flag when you run the commandmake. You will not need to run gcc directly, like I do here.
Another common reason for Numba not being able to compile your code is that itcannot statically determine the return type of a function. The most likelycause of this is the return type depending on a value that is available only atruntime. Again, this is most often problematic when usingnopython mode. The concept of type unification is simply trying to finda type in which two variables could safely be represented. For example a 64 bitfloat and a 64 bit complex number could both be represented in a 128 bit complexnumber.
Numba (version 0.42.0 and later) has some additional functions relating togdb support for CPUs that make it easier to debug programs. All the gdbrelated functions described in the following work in the same mannerirrespective of whether they are called from the standard CPython interpreter orcode compiled in either nopython mode or object mode.
Calling numba.gdb() and/or numba.gdb_init() more thanonce in the same program is not advisable, unexpected things mayhappen. If multiple breakpoints are desired within a program,launch gdb once via numba.gdb() or numba.gdb_init()and then use numba.gdb_breakpoint() to register additionalbreakpoint locations.
It can be seen in the above example that execution of the code is paused at thelocation of the gdb() function call at end of the numba_gdb_breakpointfunction (this is the Numba internal symbol registered as breakpoint withgdb). Issuing a step at this point moves to the stack frame of thecompiled Python source. From there, it can be seen that the variables a andb have been evaluated but c has not, as demonstrated by printing theirvalues, this is precisely as expected given the location of the gdb() call.Issuing a next then evaluates line 7 and c is assigned a value asdemonstrated by the final print. 2b1af7f3a8