[RFAv3 6/6] NEWS and documentation for | (pipe) command.

[Philippe Waroquiers]

gdb/ChangeLog
	* NEWS: Mention new pipe command and new convenience variables.

gdb/doc/ChangeLog
	* gdb.texinfo (Shell Commands): Document pipe command.
	(Logging Output): Add a reference to pipe command.
	(Convenience Variables): Document $_shell_exitcode and
	$_shell_exitstatus.
---
 gdb/NEWS            | 32 ++++++++++++++--------
 gdb/doc/gdb.texinfo | 67 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 88 insertions(+), 11 deletions(-)

diff --git a/gdb/NEWS b/gdb/NEWS
index b21b2cbb47..570718ab5c 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -16,11 +16,23 @@
 
 * Support for Pointer Authentication on AArch64 Linux.
 
-* Two new convernience functions $_cimag and $_creal that extract the
+* Two new convenience functions $_cimag and $_creal that extract the
   imaginary and real parts respectively from complex numbers.
 
+* New built-in convenience variables $_shell_exitcode and $_shell_exitsignal
+  provide the exitcode or exit status of the shell commands launched by
+  GDB commands such as "shell", "pipe", "make".
+
 * New commands
 
+pipe [COMMAND] | SHELL_COMMAND
+| [COMMAND] | SHELL_COMMAND
+pipe -d SEP COMMAND SEP SHELL_COMMAND
+| -s DEP COMMAND SEP SHELL_COMMAND
+  Executes COMMAND and sends its output to SHELL_COMMAND.
+  With no COMMAND, repeat the last executed command
+  and send its output to SHELL_COMMAND.
+
 set print max-depth
 show print max-depth
   Allows deeply nested structures to be simplified when printing by
@@ -28,16 +40,6 @@ show print max-depth
   The default max-depth is 20, but this can be set to unlimited to get
   the old behavior back.
 
-* Python API
-
-  ** The gdb.Value type has a new method 'format_string' which returns a
-     string representing the value.  The formatting is controlled by the
-     optional keyword arguments: 'raw', 'pretty_arrays', 'pretty_structs',
-     'array_indexes', 'symbols', 'unions', 'deref_refs', 'actual_objects',
-     'static_members', 'max_elements', 'repeat_threshold', and 'format'.
-
-* New commands
-
 set may-call-functions [on|off]
 show may-call-functions
   This controls whether GDB will attempt to call functions in
@@ -48,6 +50,14 @@ show may-call-functions
   an error when a command (such as print expression) calls a function
   in the program.
 
+* Python API
+
+  ** The gdb.Value type has a new method 'format_string' which returns a
+     string representing the value.  The formatting is controlled by the
+     optional keyword arguments: 'raw', 'pretty_arrays', 'pretty_structs',
+     'array_indexes', 'symbols', 'unions', 'deref_refs', 'actual_objects',
+     'static_members', 'max_elements', 'repeat_threshold', and 'format'.
+
 *** Changes in GDB 8.3
 
 * GDB and GDBserver now support access to additional registers on
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index dd8ae91b93..36e3f8bc35 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -1454,6 +1454,56 @@ Execute the @code{make} program with the specified
 arguments.  This is equivalent to @samp{shell make @var{make-args}}.
 @end table
 
+@table @code
+@kindex pipe
+@kindex |
+@cindex send the output of a gdb command to a shell command
+@anchor{pipe}
+@item pipe [@var{command}] | @var{shell_command}
+@itemx | [@var{command}] | @var{shell_command}
+@itemx pipe -d @var{sep} @var{command} @var{sep} @var{shell_command}
+@itemx | -d @var{sep} @var{command} @var{sep} @var{shell_command}
+Executes @var{command} and sends its output to @var{shell_command}.
+Note that no space is needed around @code{|}.
+If no @var{command} is provided, the last command executed is repeated.
+
+If the @var{command} contains a @code{|}, then the option @code{-d @var{sep}}
+can be used to specify an alternate separator string @var{sep} that separates
+the  @var{command} from the @var{shell_command}.
+
+Example:
+@smallexample
+@group
+(gdb) pipe p full|wc
+      5      17      81
+(gdb) |p full|wc -l
+5
+@end group
+@group
+(gdb) p full
+$4 = (black => 144,
+  red => 233,
+  green => 377,
+  blue => 610,
+  white => 987)
+(gdb) ||grep red
+  red => 233,
+@end group
+@group
+(gdb) | -d ! echo this contains a | char\n ! sed -e 's/|/PIPE/'
+this contains a PIPE char
+(gdb) | -d xxx echo this contains a | char!\n xxx sed -e 's/|/PIPE/'
+this contains a PIPE char!
+(gdb)
+@end group
+@end smallexample
+@end table
+
+The convenience variables @code{$_shell_exitcode} and @code{$_shell_exitsignal}
+can be used to examine the exit status of the last shell command launched
+by @code{shell}, @code{make}, @code{pipe} and @code{|}.
+@xref{Convenience Vars,, Convenience Variables}.
+
 @node Logging Output
 @section Logging Output
 @cindex logging @value{GDBN} output
@@ -1482,6 +1532,8 @@ Set @code{redirect} if you want output to go only to the log file.
 Show the current values of the logging settings.
 @end table
 
+You can also redirect the output of a @value{GDBN} command to a
+shell command.  @xref{pipe}.
 @node Commands
 @chapter @value{GDBN} Commands
 
@@ -11292,6 +11344,21 @@ the value 12 for @code{$_gdb_minor}.  These variables allow you to
 write scripts that work with different versions of @value{GDBN}
 without errors caused by features unavailable in some of those
 versions.
+
+@item $_shell_exitcode
+@itemx $_shell_exitsignal
+@vindex $_shell_exitcode@r{, convenience variable}
+@vindex $_shell_exitsignal@r{, convenience variable}
+@cindex shell command, exit code
+@cindex shell command, exit signal
+@cindex exit status of shell commands
+@value{GDBN} commands such as @code{shell}, @code{|} are launching
+shell commands.  When a launched command terminates, @value{GDBN}
+automatically maintains the variables @code{$_shell_exitcode}
+and @code{$_shell_exitsignal} according to the exit status of the last
+launched command.  These variables are set and used similarly to
+the variables @code{$_exitcode} and @code{$_exitsignal}.
+
 @end table
 
 @node Convenience Funs
-- 
2.20.1