ConEmu
Windows Terminal

Troubleshooting Cygwin and Msys problems

Please, don’t report third-party bugs on the ConEmu issue tracker, report cygwin and msys bugs to their authors!

ConEmu is a terminal! It’s just the display for the output of your console applications. Bugs in these applications will lead to wrong behaviour and display output in ConEmu.

If you think that the problem is in ConEmu? Read the rest of this wiki first.

Some techinfo first

There are three types of Windows console (terminal) emulators:

TTY style

Most of this type emulators are based on ‘POSIX layer’ - cygwin, msys or msysgit. msys was forked long ago from cygwin, that is why they are alike in many cases. In turn, there is another fork - msysgit was forked from msys…

When TTY emulator starts it establishes stdin/stdout redirection where it may process control sequences emitted by console application.

TTY Pros

Very fast output. Really. No need to use ‘slow’ Windows console subsystem, that’s why the speed is limited mainly with pipe throughput.

‘Easy’ implementation of ANSI support. All ANSI codes are processed inside the emulator. No need to translate them to and from Windows console subsystem.

Almost unlimited backscroll buffer (depends on implementation).

TTY Cons

User can’t run here large amount of programs designed for Windows console. For example, Powershell and Far Manager can’t be started at all. Official Vim is not working. cmd.exe can do something here, but command history (Up arrow) is not working. And so on…

In other words, if your console application was not linked with cygwin1.dll or msys-2.0.dll there are chances it’s not working properly in TTY terminal.

Windows console API style

These emulators always have hidden standard Windows console window. Say, they are wrappers around Windows console API. That means all programs designed for Windows console sybsystem are expected to work properly. Using these emulators, users will get bonuses like easy resizing, convenient copy/pasting, hyperlinks processing, etc.

ConAPI Pros

Programs running in classic consoles have access to full set of Windows classic console API. That’s why applications utilizing this set of API work way better compared with cygwin terminals.

ConAPI Pros

On the other hand, programs designed for ‘POSIX layer’ may fails here or there… For example, there were a lot of complains about ssh-ing to remove machines from the classic consoles.

Complains

I regularly get emails and issues about cygwin/msys compatibility with ConEmu. Most of them does not have anything to fix inside ConEmu sources, but users complain me instead of cygwin/msys developers.

Let me draw an analogue. There is a great tool RPP, but it is an MacOS application. How can you run it on Windows? Set up VMWare with MacOS inside :-D

The same with POSIX console applications in Windows. If you want to run them properly - run them in mintty. That is weird for my taste… If you develop Windows console application, it must be able to run in Windows standard console window. Well, it may show some lack of features (like 256 colors processing) but it must be working properly in all other cases.

Windows power

Windows standard console supports 16 color palette, 32K lines of backscroll buffer, alternative screens, Unicode, mouse input and dozens of other features. The main complains of Linux users - unfriendly clipboard support (copy/paste) and window resizing. Really, ‘unfriendly’ but not an ‘absent’. So, if you are using ConEmu or similar emulator - copy/paste/resize is not a problem at all…

What I want to say. Windows console is powerful subsystem. Just run there proper shell. If you like bash - just run it!

Problems with cygwin

Before reporting cygwin-related problem to me, please check it first in the standard Windows console.

Just run your shell from Win+R, for example C:\cygwin\bin\sh.exe -l -i, ensure your console window has the same buffer and window sizes as in ConEmu (right click on the console caption, choose ‘Properties’ and change sizes), and try to reproduce your problem.

I believe, your problem will repeats in standard Windows console (many users erroneously name it ‘cmd.exe’).

In fact, there are a few bugs which were really related to ConEmu (and was fixed long ago): Issue 1549: Alternative screen and clearing screen (Ctrl+L).

But in most of cases, your problem will repeats outside of ConEmu. That means, you should contact cygwin team, because ‘console application must work properly in the console’. But in your case, cygwin acts properly only under certain terminal emulators (mintty), which are not real consoles in fact.

cygwin/msys terminal connector

Experimental approach to implement POSIX-compatible terminal (pty) emulation is on the go.

Well, in fact, cygwin/msys connector is a simple tool which forces cygwin/msys core to disable ANSI processing and let it just pass ANSI sequences to terminal unmodified.

Why the terminal application must create special hacks to disable ANSI processing? I have not idea… Just a simple switch would be enough, but it does not exist.

Anyway, anyone may go to cygwin/msys connector, download fresh test release, update ConEmu to the latest ALPHA version, change your cygwin/msys task startup command and use console tools in ConEmu’s native way.

How to save bash’s history on window close

By default, bash saves history on normal exit. But you may to force it to append each command immediately, just add to your .bashrc:

PROMPT_COMMAND="history -a; $PROMPT_COMMAND"

Or even more handy variant:

# Save timestamp in the history file
HISTTIMEFORMAT="%F %T "
# Don't store duplicates
HISTCONTROL=ignoredups
# Allow "sharing" of history between instances
PROMPT_COMMAND="${PROMPT_COMMAND:+$PROMPT_COMMAND$'\n'}history -a; history -c; history -r"

NB Read about cygwin/msys terminal connector above.

Few helpful keybindings for .inputrc

# Ctrl-Left
"\e[1;5C": forward-word

# Ctrl-Right
"\e[1;5D": backward-word

# Ctrl-Del
"\e[3;5~": kill-word

# Ctrl-BS - kill word on the left
"\x1F": "\C-w"

# Ctrl-K - resets the terminal (commented, I prefer binding below)
# "\C-k": "\C-e\C-uecho -e \"\\033c\\c\"\n"

# Ctrl-K - clears the input line regardless of cursor pos
"\C-k": "\C-e\C-u"

NB Read about cygwin/msys terminal connector above.

Report examples

Broken screen output

Was happen with alternative screens. There was several bugs related and they was fixed in cygwin. As I said, nothing to do with ConEmu, just ask cygwin team to make it work in Windows console. Seems like reported problems of that class are already fixed within cygwin.

Some related issues: Issue 1397: Clearing buffer after quiting VIM, LESS, MAN etc. in Cygwin, Issue 1537: screen is wiped out after quiting vi.

Mouse do not working

Mouse do working in mintty but don’t in standard Windows console. For example, mc ignores mouse clicks when it is started from “cmd.exe”. That is because mintty send escape sequences to the terminal input (unix-like), but Windows standard describes special input event - MOUSE_EVENT_RECORD. Take a look at Far Manager or official Vim. They perfectly support mouse input.

You may read more about console input in msdn: ReadConsoleInput, INPUT_RECORD, MOUSE_EVENT_RECORD.

Some related issues:

ANSI support

One may notice that colors in the mintty are “nice” but in the ConEmu are “ugly”. That is because cygwin (ncurses actually, thought) does not send escape sequences to the terminal output but process them internally.

Cygwin does not want to know anything about ConEmu. I can understand this point of view.

Read more in wiki CygwinAnsi.

Startup directory

Cygwin shell always starts in your "${HOME}" instead of specified working folder.

How to change that behaviour - read in wiki CygwinStartDir.

Bottom line

My position is simple: if you are writing console application for Windows - just make it working in Windows. Report your problems related to Windows console to cygwin team here: dir.gmane.org/gmane.os.cygwin.

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