I'm using mingw with msys and mintty on windows. I have a problem that msys and mintty are somehow not flushing output until a command is finished. This means I can't really run any interactive programs.
For example, if I have in C:
printf("Test\n");
the output won't appear until the program has terminated. However, if I have:
printf("Test\n"); fflush(stdout);
then the output appears immediately. If I use msys without mintty or the windows console, then everything works normally.
So my question, what's going on with msys and mintty?
This can be an issue when msys uses the rxvt shell under a number of scenarios. In cases where I see this problem, I ask msys to use the native Windows shell for its console. For example:
C:\MinGW\msys\1.0\msys.bat --no-rxvt
I thought that modern MSYS installations default to using the native shell as MSYS developers seem to prefer it. I have other issues with the native shell that drive me to use the rxvt shell, so I do infrequently run into this issue.
C:\MinGW\msys\1.0\msys.bat --rxvt
I find that the rxvt shell usually works fine except for certain applications that are built as "console" utilities meant to run from a command-line.
The only thing that worked for me was to precede the command with winpty ...
$ winpty java ClassName
It causes unbuffered output to be 3x slower and buffered output to be 5x slower (in my case, with Java).
To always have a command invisibly invoked by winpty ...
$ cd ~
$ pwd -W
... add the following line to .bashrc ...
alias java="winpty java"
... then restart terminal and ignore the (one-time) warning message.
来源：https://stackoverflow.com/questions/35109086/msys-not-flushing-output