Passing data to a shell'ed command

Passing data to a shell'ed command

[Shawn McCarney]

I need to create a user-defined command that reads some memory and then
passes it a formatting program.  I am assuming the formatting program would
be run via the 'shell' command'.  Is there any way to do this?

Below is a list of the things that I have thought of.  None of them seem to
be possible:

* Writing the command output to a file (this is my preferred approach)
* Passing output as stdin to a child process
* Setting an environment variable which contains the output
* Passing output as command line parameters to a child process

The data could be passed as command parameters if the 'shell' command
expanded convenience variables.  However, it doesn't seem to.

The only solution I have found so far is to require the user to run DDD and
then parse the ~/.ddd/log file.  However, this is a strange restriction on
the users.  It also might not work reliably due to buffered I/O.

Another possible solution would be to call C runtime I/O functions as part
an expression in a 'set' command.  However, these functions would be
running on the target, not the gdb host machine right?

Any other ideas?  Someone must have solved this already...

Shawn McCarney (shawnmm@us.ibm.com)

Re: Passing data to a shell'ed command

[Eli Zaretskii]

On Tue, 3 Jul 2001, Shawn McCarney wrote:

> I need to create a user-defined command that reads some memory and then
> passes it a formatting program.  I am assuming the formatting program would
> be run via the 'shell' command'.  Is there any way to do this?
> 
> Below is a list of the things that I have thought of.  None of them seem to
> be possible:
> 
> * Writing the command output to a file (this is my preferred approach)
> * Passing output as stdin to a child process
> * Setting an environment variable which contains the output
> * Passing output as command line parameters to a child process

I'd suggest

 * add a special function to the debuggee which will accept the
   command line for the formatting program, and then run that
   program.  Then use the GDB `call' command to invoke that function
   from GDB.

> Another possible solution would be to call C runtime I/O functions as part
> an expression in a 'set' command.  However, these functions would be
> running on the target, not the gdb host machine right?

Ah, you are debugging a remote target?  Than my suggestion won't work
for you.

Sounds like a good reason for extending `shell', or maybe a new
command.