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 + + * gdb.texinfo (pipe command): New node. + 2011-08-25 Andrew Oakley * 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 18:39:03.200191037 +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{args} +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 + +@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
print dd_tbl
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{
}} 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