What does Can't open ../scripts/newer*: No such file or directory* mean? I got it while trying to build Exim.

You are using FreeBSD, or another OS that has a make command which tries to optimize the running of commands. Exim's Makefile contains targets with sequential commands like this:

buildpcre:
  @cd pcre; $(MAKE) SHELL=$(SHELL) AR="$(AR)" $(MFLAGS) CC="$(CC)" \
    CFLAGS="$(CFLAGS) $(PCRE_CFLAGS)" \
    RANLIB="$(RANLIB)" HDRS="$(PHDRS)" \
    INCLUDE="$(INCLUDE) $(IPV6_INCLUDE) $(TLS_INCLUDE)"
  @if $(SHELL) $(SCRIPTS)/newer pcre/libpcre.a exim; then \
    /bin/rm -f exim eximon.bin; fi

The second command assumes that the cd pcre in the first command is no longer in effect. If you have -j3 in your default set of MAKEFLAGS, FreeBSD make tries to optimize, and ends up up with both commands in the same shell process. The result is that $(SCRIPTS) (which has a value of ../scripts) is not found. The simplest solution is to force make to use backwards compatibility mode with each command in its own shell, by using the -B flag. To ensure that this happens throughout the build, it's best to export it in your environment:

MAKEFLAGS='-B'
ort MAKEFLAGS
e