# PetscAttachDebuggerErrorHandler
Error handler that attaches a debugger to a running process when an error is detected. This routine is useful for examining variables, etc. 
## Synopsis
```
#include "petscsys.h"   
PetscErrorCode PetscAttachDebuggerErrorHandler(MPI_Comm comm, int line, const char *fun, const char *file, PetscErrorCode num, PetscErrorType p, const char *mess, void *ctx)
```
Not Collective


## Input Parameters

- ***comm -*** communicator over which error occurred
- ***line -*** the line number of the error (indicated by __LINE__)
- ***file -*** the file in which the error was detected (indicated by __FILE__)
- ***message -*** an error text string, usually just printed to the screen
- ***number -*** the generic error number
- ***p -*** `PETSC_ERROR_INITIAL` if error just detected, otherwise `PETSC_ERROR_REPEAT`
- ***ctx -*** error handler context



## Options Database Keys

- ***-on_error_attach_debugger [noxterm,dbx,xxgdb,xdb,xldb,gdb] [-*** display name] - Activates debugger attachment
- ***-start_in_debugger [noxterm,dbx,xxgdb,xdb,xldb,gdb] [-*** display name] [-debugger_ranks m,n]





## Notes
By default the GNU debugger, gdb, is used.  Alternatives are cuda-gdb, lldb, dbx and
xxgdb,xldb (on IBM rs6000), xdb (on HP-UX).

Most users need not directly employ this routine and the other error
handlers, but can instead use the simplified interface SETERR, which has
the calling sequence
```none
SETERRQ(PETSC_COMM_SELF,number,p,message)
```


## Notes for experienced users
Use `PetscPushErrorHandler()` to set the desired error handler.  The
currently available PETSc error handlers are
```none
PetscTraceBackErrorHandler()
```
```none
PetscAttachDebuggerErrorHandler()
```
```none
PetscAbortErrorHandler()
```
or you may write your own.


## Developer Note
This routine calls abort instead of returning because if it returned then `MPI_Abort()` would get called which can generate an exception
causing the debugger to be attached again in a cycle.


## See Also
 `PetscSetDebuggerFromString()`, `PetscSetDebugger()`, `PetscSetDefaultDebugger()`, `PetscError()`, `PetscPushErrorHandler()`, `PetscPopErrorHandler()`, `PetscTraceBackErrorHandler()`,
`PetscAbortErrorHandler()`, `PetscMPIAbortErrorHandler()`, `PetscEmacsClientErrorHandler()`, `PetscReturnErrorHandler()`, `PetscSetDebugTermainal()`

## Level
developer

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/sys/error/adebug.c.html#PetscAttachDebuggerErrorHandler">src/sys/error/adebug.c</A>


---
[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/sys/error/adebug.c)


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