That segment is for if you were building a script to compile glibc automatically in order to run it on this system. The "i?86" is a pattern; if the outut of
uname -m matches it, it will run the following commands until it gets to
You probably don't need it; it was specifically meant to figure out if your architecture type was i386 since glibc doesn't support it anymore.
If you're building it in order to run it on a different system that is not x86_64 (or to run it on this system, but using only 32-bit instructions), then you want to force compiling for i486. You can get rid the
case structure completely by converting
case `uname -m` in
i?86) echo "CFLAGS += -march=i486 -mtune=native" > configparms ;;
echo "CFLAGS += -march=i486 -mtune=native" > configparms