Re: [PATCH][TEST-CASE][DOC] Implementation of pipe to pass GDB's command output to the shell.

[Abhijit Halder <abhijit dot k dot halder at gmail dot com>]

On Tue, Aug 30, 2011 at 8:18 PM, Abhijit Halder
<abhijit.k.halder@gmail.com> wrote:
> On Tue, Aug 30, 2011 at 8:01 PM, Abhijit Halder
> <abhijit.k.halder@gmail.com> wrote:
>> On Tue, Aug 30, 2011 at 7:57 PM, Pedro Alves <pedro@codesourcery.com> wrote:
>>> On Tuesday 30 August 2011 14:58:02, Abhijit Halder wrote:
>>>> +@table @code
>>>> +@item pipe @var{args}
>>>
>>> I suggest writing this as something like:
>>>
>>> @item pipe @var{delim} @var{gdbcmd} @var{delim} @var{shellcmd}
>>>
>>> and then adjust the text a bit to refer to the variables by name.
>>> The syntax is more immediately obvious this way.
>>>
>>>> +The @var{args} consists of a delimiter followed by a @value{GDBN} command,
>>>> +followed by the same delimiter and finally a shell command. ?The delimiter is a
>>>> +string of arbitrary length, containing no whitespace and no leading '-', acts
>>>> +as a separator between a @value{GDBN} command and a shell command. ?The shell
>>>> +command should be in compliance with the syntax of the default shell.
>>>> +@end table
>>>
>>> --
>>> Pedro Alves
>>>
>>
>> Sure. I am going to change this.
>>
>
> Hi all,
>
> In gdb.texinfo file I have seen @cindex and @kindex markup. Someone
> please tell me the significance of them.
> Secondly, the example I have used is from a sample code written by me
> just for this purpose. This should not have any licensing issue I
> hope.
>

Changes as suggested by Pedro.

Regards,
Abhijit Halder

diff -rup src/gdb/doc/ChangeLog dst/gdb/doc/ChangeLog
--- src/gdb/doc/ChangeLog	2011-08-27 20:35:38.459934029 +0530
+++ dst/gdb/doc/ChangeLog	2011-08-28 16:24:53.024714073 +0530
@@ -1,3 +1,7 @@
+2011-08-29  Abhijit Halder  <abhijit.k.halder@gmail.com>
+
+	* gdb.texinfo (pipe command): New node.
+
 2011-08-25  Andrew Oakley  <andrew@ado.is-a-geek.net>
 
 	* gdb.texinfo (Types In Python): Document 'bitpos' for enums.
diff -rup src/gdb/doc/gdb.texinfo dst/gdb/doc/gdb.texinfo
--- src/gdb/doc/gdb.texinfo	2011-08-26 21:11:39.938354007 +0530
+++ dst/gdb/doc/gdb.texinfo	2011-08-30 20:09:24.120190599 +0530
@@ -1367,6 +1367,53 @@ Execute the @code{make} program with the
 arguments.  This is equivalent to @samp{shell make @var{make-args}}.
 @end table
 
+If you want to process the output of a @value{GDBN} command using some shell
+command or some script, that can be done by using the command @code{pipe}.  You
+don't even need to get a shell for that.  The same could be achieved by
+enabling logging and redirecting the output of @value{GDBN} command to some
+file and then processing the file content by invoking a shell using
+@code{shell} command.  But this incurs higher costs as the explicit invokation
+of shell involves execution of its startup scripts and locating the file
+containing @value{GDBN}'s command output involves directory lookup; even though
+OS may optimize these processes by its cache mechanism.
+
+@table @code
+@item pipe @var{dlim} @var{gdbcmd} @var{dlim} @var{shellcmd}
+@var{dlim} is a string of arbitrary length, containing no whitespace and no
+leading '-', acts as a separator between a @value{GDBN} command @var{gdbcmd}
+and a shell command @var{shellcmd}.  The shell command should be in compliance
+with the syntax of the default shell.
+@end table
+
+@smallexample
+(@value{GDBP}) @b{ptype dd_tbl}
+type = struct dd @{
+    int dd_handle;
+    const char *dd_name;
+    int dd_major;
+    int dd_minor;
+    void *dd_code;
+    void *dd_data;
+@} [1024]
+(@value{GDBP}) @b{pipe <br> print dd_tbl <br> sed 's/@}/\n/g' | grep @
+"\.test_dd" | tr ',' '\n'}
+
+  @{dd_handle = 10
+  dd_name = 0x8048538 ".test_dd"
+  dd_major = 100
+  dd_minor = 0
+  dd_code = 0xcc
+  dd_data = 0x80
+@end smallexample
+
+In the above example @samp{@var{<br>}} acts as a delimiter.  The output of
+@samp{print dd_tbl} is passed to the shell command @samp{sed 's/@}/\n/g' | @
+grep ".test_dd" | tr ',' '\n'} for processing.
+
+In the given example the output of @value{GDBN} command is huge and not well
+formated.  The use of shell commands like ``sed'', ``tr'' and ``grep'' ease
+the searching of desired pattern and hence ease debugging.
+
 @node Logging Output
 @section Logging Output
 @cindex logging @value{GDBN} output