Kile (I'm using version 2.9.91 of Kile) creates its lyx pipe in /tmp. Kbibtex does not seem to be able to detect it automatically (the 'send to LyX/Kile' feature does not work). However, if I manually specify the location of the pipe in 'settings > configure kbibtex > saving and exporting > Manually specified LyX pipe', I am able to use the aforementioned feature properly. Kbibtex should also search in /tmp for a Lyx pipe.
I am suprised that you encounter this problem. I make a fresh installation of Kile 2.9.91. It created its Lyx pipes in /tmp using a random name, but it created symbolics to these pipes from the two traditional locations which KBibTeX check by default: # ls -l /home/testuser/.lyxpipe.in lrwxrwxrwx 1 testuser testuser 27 18 apr 20.23 /home/testuser/.lyxpipe.in -> /tmp/kile-dhJsCe.lyxpipe.in # ls -l ll /home/testuser/.lyx/lyxpipe.in lrwxrwxrwx 1 testuser testuser 31 18 apr 20.23 /home/testuser/.lyx/lyxpipe.in -> /tmp/kile-dhJsCe.lyx/lyxpipe.in The problem is that KBibTeX does not follow those symbolic links to the actual pipe, i.e. it technically correctly detects the symbolic links as symbolic links but not as pipes. I'll prepare a patch to fix this problem.
A minor update to my previous comment, it contained an earlier draft of my comment. Please ignore the initial "I am suprised that you encounter this problem.".
Git commit 23ce89b6b09b7264231038506231c6b1d35d69d1 by Thomas Fischer. Committed on 18/04/2018 at 19:19. Pushed by thomasfischer into branch 'kbibtex/0.8'. Resolving symbolic links to LyX pipe Newer Kile versions (at least 2.9.91) create the LyX pipe files in /tmp (on Linux systems, at least) and then place symbolic links to those pipes in the user's home directory both as ~/.lyxpipe.in and ~/.lyx/lyxpipe.in (for the 'in' pipe). Before this patch, KBibTeX would detect those symbolic links and discard them as not being named pipes instead of resolving them to get the real named pipe. As introduced in this patch, symbolic links are resolved using QFileInfo::canonicalFilePath(). As another change introduced in this patch, the previous code duplication when checking both in ~/ and ~/.lyx for a LyX pipe has been addressed. FIXED-IN: 0.8 M +8 -27 src/processing/lyx.cpp https://commits.kde.org/kbibtex/23ce89b6b09b7264231038506231c6b1d35d69d1
Git commit 6d1b52bac177032fb401cb4fa1574e5e4161f91b by Thomas Fischer. Committed on 18/04/2018 at 19:20. Pushed by thomasfischer into branch 'master'. Resolving symbolic links to LyX pipe Newer Kile versions (at least 2.9.91) create the LyX pipe files in /tmp (on Linux systems, at least) and then place symbolic links to those pipes in the user's home directory both as ~/.lyxpipe.in and ~/.lyx/lyxpipe.in (for the 'in' pipe). Before this patch, KBibTeX would detect those symbolic links and discard them as not being named pipes instead of resolving them to get the real named pipe. As introduced in this patch, symbolic links are resolved using QFileInfo::canonicalFilePath(). As another change introduced in this patch, the previous code duplication when checking both in ~/ and ~/.lyx for a LyX pipe has been addressed. M +8 -27 src/processing/lyx.cpp https://commits.kde.org/kbibtex/6d1b52bac177032fb401cb4fa1574e5e4161f91b