Interesting article on boot ordering

[Chris Adams]

Once upon a time, Bill Nottingham <notting at redhat.com> said:
> For example, we just in the past day or two got rid of 41 shell invocations
> on boot just by changing how grep was built. Always look for the big wins
> first. :)

Yeah, I've got a bit in my standard profile script that strips out
instances of the "standard" directory from the path and re-adds them at
the beginning in a specified order (so you don't get duplicates, they
are in an expected order, etc.).  This used to take forever, but I
managed to make it run entirely with no external calls (including no
forks, no subshells, etc.).

########################################################################
# Set the base PATH here
BASEPATH=/usr/local/bin:/usr/bin:/bin
BASEPATH=$BASEPATH:/usr/X11R6/bin
BASEPATH=$BASEPATH:/usr/games
BASEPATH=$BASEPATH:/usr/local/sbin:/usr/sbin:/sbin
BASEPATH=$HOME/bin:$BASEPATH

# Split the base PATH and PATH into arrays for searching
IFS=":$IFS"
BASEARRAY=($BASEPATH)
PATHARRAY=($PATH)
IFS="${IFS#:}"

# Now remove any instances of the base PATH from the PATH and put them
# at the front
PATH=$BASEPATH
for pdir in ${PATHARRAY[*]}; do
	cont=0
	for bdir in ${BASEARRAY[*]}; do
		if [ "$pdir" = "$bdir" ]; then
			cont=1
			break
		fi
	done
	[ "$cont" = 1 ] && continue
	PATH="$PATH:$pdir"
done
unset BASEPATH BASEARRAY PATHARRAY pdir cont bdir
export PATH

########################################################################

The "BASEARRAY=($BASEPATH)" is a bash specific thing; the same effect
can be had in ksh with "set -A BASEARRAY $BASEPATH", but that is ksh
specific (I don't know of a POSIX shell way of doing that).

It seems like a little thing, but optimizing shell scripts can make a
big difference.
-- 
Chris Adams <cmadams at hiwaay.net>
Systems and Network Administrator - HiWAAY Internet Services
I don't speak for anybody but myself - that's enough trouble.