Debugger Console App: what changed

Revision 2 to 3. Removed lines have a minus sign; added lines have a plus sign.

Old	New		Line
1	1		## Introduction
2	2
3	3		This page contains information on how to debug console applications in Lazarus. That is where to find the output (writeln) of your app, and where to type the input (readln).
4	4
5	5		This page was written for Lazarus 0.9.30 and above.
6	6
7	7		## Windows
8	8
9	9		On Windows, the application will open its own console window, just as it would outside the debugger. There is no need to do anything special apart from adding a `ReadLn;` before the application terminates so that the console window does not automatically close until you press `Enter`.
10	10
11	11		## Linux
12	12
13	13		### Lazarus 0.9.30 / 0.9.30.2
14	14
15	15		Please see the notes in the#Mac section.
16	16
17	17		### Lazarus 0.9.31 / 1.0 and higher
18	18
19	19		You can open a console window from the menu: "View" =\> "Debug Windows" =\> "Terminal Output"
20	20
21	21		It shows the raw output of your application. Note it has no support for any escape sequences, as some terminals may have. Anything you type into this window will be sent to your application.
22	22
23	23		## Mac & Linux
24	24
25	25		Unfortunately there is currently no built-in support for debugging console applications.
26	26
27	27		Console applications do not have their own terminal, but use the terminal they were started from (the terminal of the shell they were started from). When started from within Lazarus, there is no such terminal. You can specify a "starter application" (like xterm) under menu "Run" =\> "Run parameters". however this only works if you start your application without a debugger. This does not work for debugging.
28	28
29	29		There are a couple of workarounds.
30	30
31	31		### Redirect output to file
32	32
33	33		In menu "Run" =\> "Run parameters": specify in "command line parameters":
34	34
35		-	~~` >/somedir/somefile`~~
	35	+	```text
	36	+	>/somedir/somefile
	37	+	```
36	38
37	39		Then outside Lazarus open a shell and run
38	40
39	41		``` bash
40	42		tail -f /somedir/somefile
41	43		```
42	44
43	45		### Redirect input and output to a pty (terminal)
44	46
45	47		Open a terminal outside of Lazarus and run
46	48
47	49		```bash>
48	50		pty
49	51		</syntaxhighlight>
50	52		On Ubuntu 18, the command is
51	53		<syntaxhighlight lang=
52	54		```
53	55
54	56		tty
55	57
56	58		It should return something like
57	59
58		-	~~` /dev/pty/2`~~
	60	+	```text
	61	+	/dev/pty/2
	62	+	```
59	63
60	64		The exact value depends on the OS and the number of terminals already open.
61	65
62	66		Note
63	67		The returned value is only valid as long as the terminal stays open, so if you open a new terminal next time you debug in Lazarus, you need to adapt all settings to the new value.
64	68
65	69		In menu "Run" =\> "Run parameters": specify in "command line parameters":
66	70
67		-	~~` >/dev/pty/2 </dev/pty/2`~~
	71	+	```text
	72	+	>/dev/pty/2 </dev/pty/2
	73	+	```
68	74
69	75		If you want to use the terminal to send input to your application, then you may need to stop the shell in it from reacting to the input (unless you started a terminal without a shell). Run something like
70	76
71	77		``` bash
72	78		tail -f /some/empty/file/that/does/not/change
73	79		```
74	80
75	81		> Note: This means you still can't use ctrl-c in the input.
76	82
77	83		#### Debugger startup options
78	84
79	85		In the global options dialog, on the debugger page, you can specify parameters given to gdb (do *not* use the in/output redirect \> or \< here, which is meant for interactive bash but use something like --args).
80	86
81	87		It may be possible to specify the pty here, but there is currently no further info.
82	88
83	89		### gdbserver
84	90
85	91		Use the gdbserver based debugger. You can start gdbserver on the same computer as the IDE. Run gdbserver inside the terminal that you want to use for your stdout/stdin
86	92
87	93		### Lazarus 0.9.31
88	94
89	95		In the global options dialog, on the debugger page is an entry "ConsoleTty". You can enter the result of "pty" here. Then you do not need to specify any \< or \> redirects.
90	96
91	97		### Lazarus 2.x with LLDB on macOS aarch64
92	98
93	99		In the global options dialog, on the debugger page there is a "LaunchNewTerminal" option when LLDB is selected (currently the only option for this platform).
94	100
95	101		However if you tick that without making the following prerequisites, lldb (and thus Lazarus) will freeze.
96	102
97	103		1, First of all, check that your terminal shell is listed in the /etc/shells file.
98	104
99	105		You can check your current shell by this command:
100	106
101	107		``` bash
102	108		echo $SHELL
103	109		```
104	110
105	111		And list the current contents of this file by this command:
106	112
107	113		``` bash
108	114		cat /etc/shells
109	115		```
110	116
111	117		If you installed your shell e.g. via Homebrew, your shell is probably not on the list. In this case you can add it manually, to make the following commands will work.
112	118
113	119		If you have to edit this file, be extremely cautious, and do it on your own risk! You have been noticed!
114	120
115	121		2, (Optional step) If you use different terminal emulator than the default one, you can test the following command.
116	122
117	123		``` bash
118	124		osascript -e "tell application \"Terminal\" to do script \"echo lazarus\""
119	125		```
120	126
121	127		The system protection dialog should pop-up, about do you allow xy application to control the terminal. You should answer yes, and check that the freshly popped-up built-in terminal app writes "lazarus".
122	128
123	129		3, Open Lazarus. Define a new external tool in the Tools menu, with the program of /bin/sh and the following parameters.
124	130
125	131		``` bash
126	132		-c 'osascript -e "tell application \"Terminal\" to do script \"echo lazarus\""'
127	133		```
128	134
129	135		After you've added the tool, restart Lazarus, and click on it. The same system protection dialog will pop up, but for Lazarus now. Say yes, to allow it.
130	136
131	137		After doing these prerequsities, you can safely tick the "LaunchNewTerminal" option in the global settings, and every time you start a debugging, you can control stdin/stdout of the debugged program in a separate terminal window.
132	138
133	139		Note: Debugging will be really, really, really slow, unless you add the dedicated Debug/Release modes to your project, and use the Debug one for debugging. Use Dwarf2 symbols at the moment when possible.
134	140
135	141		## See also
136	142
137	143		- [[GDB Debugger Tips\|General tips/info on debugging]]
138	144
139	145		---
140	146		From the Free Pascal wiki, page "Debugger Console App", as it stood on 2023-06-18 after a change by Shaglonux, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).
141	147		Category: Debugging
142	148		Category: Lazarus

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