Vegard: What version of screen are you using? (screen -v). I suspect you're using screen compiled to use named pipes instead of unix domain sockets.
My guess at the moment is this: - Since you're running these commands inside an already existing screen session (i.e. STY defined), instead of launching new screen processes, it will ask the already running window manager to launch new windows - The way this works is that the new screen processes communicate with the window manager, via unix domain socket or named pipe, depending on how screen was compiled. The screen opens the write end of the socket/pipe (the window manager process has the read end open), and sends a "struct msg" message down the socket/pipe. In my system, this message is 12584 bytes long i.e. sizeof(struct msg). The message starts with a magic 4 byte (int) sequence, the chars 'm', 's', 'g', and then the protocol revision number (currently at version 5). This sequence is defined as MSG_REVISION in screen.h - If you're launching one window at a time, this poses no problem. The issue arises when you have multiple screen processes writing to the same pipe concurrently. POSIX mandates that writes to a pipe of less than/equal than PIPE_BUF (4096 bytes, getconf PIPE_BUF /) be atomic. There are no guarantees of atomicity if you do larger writes. See [1]. I suspect that writes are getting interleaved, and that's what causes the magic sequence check to fail (it's reading a part of another message, and from what I've seen the messages are mainly 0's, which explains the 0x00000000). My suggestion here is to compile screen from git source (branch screen-v4), make sure that the output of the configure script shows that it's using unix domain sockets and try again. There should be no interleaving if you're using unix domain sockets. Please let me know if that works for you. [1] https://www.gnu.org/software/libc/manual/html_node/Pipe-Atomicity.html [2] http://manpages.courier-mta.org/htmlman7/pipe.7.html#pipe-7_sect4 _______________________________________________ screen-users mailing list screen-users@gnu.org https://lists.gnu.org/mailman/listinfo/screen-users
