Não tenho 100% de certeza de como você está executando esse script, mas eu o reescrevi assim (também incluí comentários):
#!/bin/sh
# This is a comment line, but the line above must be the first line
# and defines the shell that the rest of this script will use.
echo "PATH: ["$PATH"]"
# Personally, I like to include [] around vars so I can see
# exactly what they are
# Run a few network related commands
nslookup www.fiu.edu
netstate -a
traceroute www.google.com
ifconfig
# Pause the script with a question. This will stop the script
# from simply closing. Default to "y" as well so the user can
# just hit the enter key to exit.
echo -n "Finished? [y/n](y) "
read ans
# Check what the user typed - if anything
if [ "$ans" = "" -o "$ans" = "Y" -o "$ans" = "y" ]
then
# Exit with 0 to signify no issue.
exit 0
else
echo "All done, so exiting anyway :]"
exit 0
fi