c2a@c2a-desktop:~/ns-allinone-2.33/ns-2.33/hls$ set -x
+ set -x
++ echo -ne '\033]0;c2a@c2a-desktop: ~/ns-allinone-2.33/ns-2.33/hls\007'
c2a@c2a-desktop:~/ns-allinone-2.33/ns-2.33/hls$ sudo  /etc/init.d/gdm start
+ sudo /etc/init.d/gdm start
Rather than invoking init scripts through /etc/init.d, use the service(8)
utility, e.g. service gdm start

Since the script you are attempting to invoke has been converted to an
Upstart job, you may also use the start(8) utility, e.g. start gdm
gdm stop/waiting
++ echo -ne '\033]0;c2a@c2a-desktop: ~/ns-allinone-2.33/ns-2.33/hls\007'
c2a@c2a-desktop:~/ns-allinone-2.33/ns-2.33/hls$ set +x
+ set +x
c2a@c2a-desktop:~/ns-allinone-2.33/ns-2.33/hls$