perlpreben has asked for the wisdom of the Perl Monks concerning the following question:

Hi,

Unwillingly i have to use windows for a project of mine. And I need to execute an .exe file.

What I have done is to wrap this into a simple perl script, giving me somewhat control, like;

open SYS,"windows_exe_file.exe|";
while(<SYS>){
 
   #parse magic here..

}

[download]

The downside is that I cant seem to get STDOUT before the program has ran for quite a while, then it spewes out some chuncks of STDOUT. Windows problem propably. But my backup solution is to use the .exe files EXPORT function (built in reporting function, not related to perl). However, I would need to "PRESS" the the button "ESC" to the program, for it to quit and write the log files.

Is this even possible?

Replies are listed 'Best First'.
Re: execute a file, then send terminate command?
by BrowserUk (Patriarch) on Feb 04, 2012 at 13:41 UTC
    The downside is that I cant seem to get STDOUT before the program has ran for quite a while, then it spewes out some chuncks of STDOUT.

    If the executable is using buffered IO on stdout (the norm), then the pipe won't get any data until the program has filled that buffer.

    In addition, the pipe itself has a 4k buffer, which can further defer the flow of data into your perl script.

    There is little you can do about this unless you have the source to the executable and can turn autoflushing on STDOUT.

    Windows problem propably.

    Nope. You'd be in exactly the same situation under *nix.

    But my backup solution is to use the .exe files EXPORT function (built in reporting function, not related to perl). However, I would need to "PRESS" the the button "ESC" to the program, for it to quit and write the log files. Is this even possible?

    Do you need to capture the exes stdout when you are using the "EXPORT function"? Ie. You said: "for it to quit and write the log files." which suggests that in this mode the data you want is written to a file rather than stdout.

    If you do not need to capture stdout, then you may be able to feed the escape to the program via stdin:

    open SYS,"| windows_exe_file.exe" or die ...;
print SYS "EXPORT this and that to thisFile.dat";
print SYS "\e";
close SYS;

my @data = do{ open IN, 'thisFile,dat'; local $/; <IN> };

    [download]

    Otherwise, you'll probably need to use IPC::Open2 or a similar module.

    With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.

    The start of some sanity?
[reply]
[d/l]
      I think your on to something, but the \e didnt press the escape key. So now the question is, how do you send an escape key to stdin ?.......
[reply]

        You'll need to ensure that the output buffer gets flushed. Try:

        use IO::Handle;

open SYS,"| windows_exe_file.exe" or die ...;

SYS->autoflush(1);

print SYS "EXPORT this and that to thisFile.dat";
print SYS "\e";
close SYS;

my @data = do{ open IN, 'thisFile,dat'; local $/; <IN> };

        [download]
        With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.

        The start of some sanity?
[reply]
[d/l]
Re: execute a file, then send terminate command?
by kielstirling (Scribe) on Feb 04, 2012 at 13:45 UTC
    Try setting $| to 1 or use IO::Handle 
    use IO::Handle;
STDOUT->autoflush;

    [download]

    UPDATE: ignore my comments .. I read the question incorrectly

[reply]
[d/l]

Back to Seekers of Perl Wisdom