User Commands - gdb (1)

NAME

fpm-gdb(1f) - [FUNIX:FILESYSTEM] launch gdb(1) in vim(1) from fpm(1) (LICENSE:MIT)

Synopsis
Description
Options
Getting Started
Using The Mouse
Scrolling
More Info
Examples
See Also

SYNOPSIS

fpm-gdb [PROGRAM][OPTIONS][ --help|--version]

DESCRIPTION

fpm-gdb(1f) is an fpm(1) plugin that starts up gdb(1) in the vim(1) editor.
It uses the vim(1) terminal feature. The terminal feature is optional. Enter this in vim(1) to check if your version has it:
       :echo has(’terminal’)
If the result is "1" you have it.

OPTIONS

PROGRAM
if more than one application is built by the package the name must be specified. Unlike with the "fpm run" command wildcards are not permitted.

--gdb CMDS
pass initial commands to gdb(1)

-wide,-w
assume a wide screen width. Wide mode places the code in a window on the left of the screen. <C-W> followed by one of {RHKLJ} can change the window layout.

--test use subcommand "test" instead of the default "run" in order to select test programs. If --test is specified --example is ignored.

--verbose,-V
verbose mode

--version,-v
Print version information on standard output then exit successfully.

--help,-h
Print usage information on standard output then exit successfully.

In addition, the following options from the fpm(1) "run" subcommand are supported, noting that "--profile debug" is always specified as well ...

--example --no-prune --link-flag --flag --directory --compiler --c-flag --c-compiler --archiver

GETTING STARTED

Lets start in a terminal at least 132 characters wide and enter
     fpm gdb --wide
and then in the gdb(1) command window enter
    b main
    info sources
    info functions
    b file.F90:routine
    run
This will set a breakpoint at the beginning of the program, list the files in scope for debugging, list the procedures, set some other breakpoint in file "file.F90" at top of procedure "routine" and then start running

the program (with optional arguments).
Clicking on "next" would take you to the next breakpoint.

For some compilers "b 1"(e.g. Intel) might be required instead of "b main"(e.g gfortran).

Many other commands exist.
Assuming you are at your next breakpoint, you can ask where you are, list local variables and print the value of some variable, like "i"
    where
    info locals
    print i

USING THE MOUSE

Assuming your terminal window supports vim(1) mouse mode, you can use the mouse in various ways. For example

TO SET BREAK POINTS

If you click the right mouse in the code file you should get an option menu for setting and clearing breakpoints.

TO EVALATE VARIABLES

click on variables to highlight them and click the [eval] icon.

SCROLLING

The gdb and output windows will not be in Normal mode and so will not scroll by default. When focus is on the window that will not scroll enter "ctrl-W N" to go to scrollable, and enter "i" to return to the original mode.
On some platforms instead of "ctrl-W" followed by capital "N" you can define which key goes to Normal mode. For example, to define F1 to switch to Terminal-Normal mode:
     :tnoremap <F1> <C-W>N
In the gdb window in particular, you probably want to toggle between the modes, because when scrolling is on command recall is not.
When in Normal mode your interaction with the program is suspended, so you want to return to the original mode or you cannot enter commands in the gdb pane and cannot see new output or enter input in Normal mode. To leave scrollable mode (enter "i") in the pane.
Check out :help window-moving for more information on changing the window layout.

MORE INFO

General gdb instructions are beyond the scope of this discussion, but "help" in the gdb pane can get you started. At least look at watch, display, list, break, info, where, print, set, next, step, and info after you get started with the basics.
For the vim(1) terminal help go to the rightmost vim(1) window and enter ":help terminal-debug".

EXAMPLES

fpm gdb
fpm gdb --compiler gfortran
# run with initial gdb(1) commands in a file fpm gdb -wide -gdb ’source mycmds.gdb’
fpm gdb --example demo1

o	fpm run --runner ddd
o	fpm run --runner gdbgui
o	fpm run --runner gdbtui
o	fpm run --runner gdb