the appliance is running on linux and accessible via http,telnet,etc.
When I do start-shell, I can access to its filesystem.
I am trying to change the interface name, currently is input1 to port-1.
It is not possible to change in WebGui or its CLI.
Possible to access its filesystem and change the interface name??

Nobody here can tell you.

Why? Because we aren't mind readers.

Try posting some useful information such as the name/type of appliance.

the appliance was oem from a device called AXGate , a Firewall.

/ # ls
bin home lib64 opt sbin usr
dev init linuxrc proc sys var
etc lib mnt root tmp
/ # cd etc
/etc # ls
TZ inputrc profile
Wireless iproute2 protocols
ZebOS.conf ipsec.d radiusclient
blkid.tab issue random-seed
br-version ld.so.cache resolv.conf
clamd.conf ld.so.conf securetty
default ld.so.conf.d security
dhcp libnl sensors.d
dspam.conf locales.conf sensors3.conf
environment localtime ser2net.conf
freshclam.conf mke2fs.conf services
fstab mtab shadow
group network ssh
hostname nsswitch.conf ssl
hosts openldap strongswan.conf
init.d passwd usb_modeswitch.setup
inittab pool.conf version
inittab_rescue ppp wgetrc

I'd think that the owners manual would provide enough information. I'd assume that the basic steps would be similar to what one might do in a Cisco switch. In this you may have to access telnet or ssh command line and modify the "software it is running" more than looking at it from a linux sort of command I'd think. I guess there may be an alias for the ports. Can try looking at ifconfig -a maybe.