Notes about compiling and using XRN on Linux The regular-expression routines in Linux libc releases 4.6 through 5.0.9 (and possibly later releases) are very slow and can sometimes cause XRN to crash. If you notice that XRN is being particularly slow when doing things that involve regular expressions (for example, when XRN is processing a KILL file with many entries in it), or if XRN crashes and the backtrace of the crash inside a debugger shows it crashing in a descendant of regcomp() or regexec(), you are probably running into this problem. The easiest way to work around the problem is to get the GNU regex-0.12 package and use its regular expression routines instead of the ones in the Linux libc. To do that, get <URL:ftp://prep.ai.mit.edu/pub/gnu/regex-0.12.tar.gz> and follow its instructions for producing regex.o. Then, add "REGEX_OBJS=/path/regex.o" to the XRN Imakefile, where "/path/regex.o" is the full path of the regex.o file (or copy regex.o into the directory in which you are building XRN and just do "REGEX_OBJS=regex.o"), and then follow the rest of the instructions in README for producing a Makefile from the Imakefile and building XRN.