Generating ifcfg-eth0 from scratch

[JB]

The results of scan for UUID:

# grep -ir uuid /etc/init.d/
/etc/init.d/messagebus:        /bin/dbus-uuidgen --ensure

The above relates to machine-id.

# grep -ir uuid /etc/sysconfig/
/etc/sysconfig/network-scripts/ifup:if [ "$USE_NM" = "true" -a -n "$UUID" ];
 then
/etc/sysconfig/network-scripts/ifup:    nmcli con up uuid "$UUID"
/etc/sysconfig/network-scripts/ifdown:    if [ -n "$UUID" -a -z "$DEVICE" ]; 
then
/etc/sysconfig/network-scripts/ifdown:	DEVICE=$(nmcli -t --fields uuid,devices
con status | awk -F ':' "\$1 == \"$UUID\" { print \$2 }")
/etc/sysconfig/network-scripts/network-functions:get_uuid_by_config ()
/etc/sysconfig/network-scripts/network-functions:    if [ -z "$UUID" -a
"$USE_NM" = "true" ]; then
/etc/sysconfig/network-scripts/network-functions:	
UUID=$(get_uuid_by_config $CONFIG)

# grep -ir source_config /etc/sysconfig/
/etc/sysconfig/network-scripts/ifup-plip:source_config
/etc/sysconfig/network-scripts/ifup-eth:source_config
/etc/sysconfig/network-scripts/ifup-ppp:  source_config
/etc/sysconfig/network-scripts/ifup-ppp:source_config
/etc/sysconfig/network-scripts/ifdown-bnep:source_config
/etc/sysconfig/network-scripts/ifdown-ppp:source_config
/etc/sysconfig/network-scripts/ifup-plusb:source_config
/etc/sysconfig/network-scripts/ifup-post:source_config
/etc/sysconfig/network-scripts/ifdown-ipsec:source_config
/etc/sysconfig/network-scripts/ifdown-sit:source_config
/etc/sysconfig/network-scripts/ifup-isdn:source_config
/etc/sysconfig/network-scripts/ifup-ipx:source_config
/etc/sysconfig/network-scripts/ifup:	source_config
/etc/sysconfig/network-scripts/ifup:source_config
/etc/sysconfig/network-scripts/ifdown-post:source_config
/etc/sysconfig/network-scripts/ifdown-ipv6:source_config
/etc/sysconfig/network-scripts/ifup-ipsec:source_config
/etc/sysconfig/network-scripts/ifup-ippp:source_config
/etc/sysconfig/network-scripts/ifup-bnep:source_config
/etc/sysconfig/network-scripts/ifup-sit:source_config
/etc/sysconfig/network-scripts/network-functions:source_config ()
/etc/sysconfig/network-scripts/ifdown-tunnel:source_config
/etc/sysconfig/network-scripts/ifup-tunnel:source_config
/etc/sysconfig/network-scripts/ifdown-eth:source_config
/etc/sysconfig/network-scripts/ifup-ipv6:source_config
/etc/sysconfig/network-scripts/ifdown:	source_config
/etc/sysconfig/network-scripts/ifdown:source_config

The above two scan outputs (as checked by scanning for UUID) relate to
NetworkManager utilizing UUID if present in
e.g /etc/sysconfig/network-scripts/ifcfg-eth0,
with nmcli via interface to dbus, or directly via dbus-send function.
  
So, it would suggest that dbus-uuidgen is used to generate the UUID.

There is no indication that UUID in /etc/sysconfig/network-scripts/ifup-eth0
is utilized by other than NM functions.

I could be wrong on that - but by removing UUID from this file, disabling NM,
enabling /etc/init.d/network, and restarting the system it could be tested if
networking is OK.

Also, in a separate step, by doing the above, but removing (renaming) the file,
one could figure out if it is required and if so, what would be needed to
restore it (rename it back to original; use system-config-network GUI, etc);
note that there is /etc/sysconfig/networking/profiles/default/ifcfg-eth0 as
well.

JB