Code:

# Set the default system $PATH:
PATH="/usr/local/bin:/usr/bin:/bin:/usr/games"

# For root users, ensure that /usr/local/sbin, /usr/sbin, and /sbin are in
# the $PATH.  Some means of connection don't add these by default (sshd comes
# to mind).
if [ "`id -u`" = "0" ]; then
  echo $PATH | grep /usr/local/sbin 1> /dev/null 2> /dev/null
  if [ ! $? = 0 ]; then
    PATH=/usr/local/sbin:/usr/sbin:/sbin:$PATH
  fi
fi

... that grep is completely pointless. PATH is explicitly set on the line above, so it won't contain '/us/local/sbin'

suggested simplification:

Code:

# Set the default system $PATH.  For root user, include
# /usr/local/sbin, /usr/sbin, and /sbin

PATH="/usr/local/bin:/usr/bin:/bin:/usr/games"
if [ "${LOGNAME:-$( id -un )}" = "root" ]; then
    PATH=/usr/local/sbin:/usr/sbin:/sbin:$PATH
fi

Using LOGNAME will avoid an unnecessary call to id in most cases.

Code:

# Notify user of incoming mail.  This can be overridden in the user's
# local startup file (~/.bash.login or whatever, depending on the shell)
if [ -x /usr/bin/biff ]; then
 biff y 2> /dev/null
fi

Firstly, no one runs comsat any more, but even if they did, biff uses stderr to determine the tty it's on, so the 2>/dev/null completely breaks it anyway. I'd suggest just dropping this.