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    Not meant to work on pipes doesnt mean cant work on pipes. What if the application is simply doing a SEEK_END to get to the end of the file? Or maybe its doing a SEEK_CUR to find the current location. Neither of these would cause any issues if I lied to the program about the results of the seek. The only place that would break is if the application was trying to go back and overwrite data already written which it shouldnt be doing with log files. And yes, I am aware of the one-process-per-pipe limitation. This will not be a problem. Commented Feb 5, 2012 at 23:17
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    If all it does is seek to the end to append, then it should just be opening the file in append mode, so it falls into the broken category. Applications don't try to find the current location unless they need to be able to seek somewhere else, and then return to the current location, so it falls into the "you'll break it by silently failing" category. It is very unlikely that a program calls seek but doesn't really need it to work ( and if it does, it falls in the broken category ). Commented Feb 6, 2012 at 4:08
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    Not true. Many applications seek to the end of the file in case some other program has written to the file since it last did. Otherwise writing where its currently at would clobber the other program's changes. And if its reading from the file, it might want to use SEEK_CUR to get its current location so that when the program starts back up, it can resume where it left off. Commented Feb 6, 2012 at 5:00
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    @Patrick, for the former, if it is appending it should be reopening the file in append mode. In this case you are talking about reading, in which case, it doesn't make sense to skip new data it hasn't read yet ( and silently ignoring the seek would break that ). As for the latter, if it is trying to use seek to return to the same position after closing and reopening the file that will break on a pipe if you silently ignore the seek, since when it closes the pipe the server gets a SIGPIPE, which presumably makes it reset so the next client that opens the pipe starts at the beginning. Commented Feb 6, 2012 at 23:47