The full list of Slackware /etc/rc.d/rc.inet1 file 

Not use the default DHCP setting 

head -5 /etc/dhcpc/dhcpcd-eth0.info

and put it into /etc/rc.d/rc.inet1, then set

DHCP="no"            # Use DHCP ("yes" or "no")

The will achieve the same result of a serious Q&A of command 'netconfig'.

Use the default DHCP setting 

set

DHCP="yes"

File source 

Example 1. File rc.inet1

#! /bin/sh
# rc.inet1      This shell script boots up the base INET system.

HOSTNAME=`cat /etc/HOSTNAME`

# Attach the loopback device.
/sbin/ifconfig lo 127.0.0.1
/sbin/route add -net 127.0.0.0 netmask 255.0.0.0 lo

# IF YOU HAVE AN ETHERNET CONNECTION, use these lines below to configure the
# eth0 interface.

# Edit these values to set up a static IP address:
IPADDR="131.162.131.132"        # REPLACE with YOUR IP address!
NETMASK="255.255.248.0" # REPLACE with YOUR netmask!
NETWORK="131.162.128.0" # REPLACE with YOUR network address!
BROADCAST="131.162.135.255"     # REPLACE with YOUR broadcast address, if you
                        # have one. If not, leave blank and edit below.
GATEWAY="131.162.128.1" # REPLACE with YOUR gateway address!

# To use DHCP instead of a static IP, set this value to "yes":
DHCP="yes"            # Use DHCP ("yes" or "no")

# OK, time to set up the interface:
if [ "$DHCP" = "yes" ]; then # use DHCP to set everything up:
  echo "Attempting to configure eth0 by contacting a DHCP server..."
  /sbin/dhcpcd
elif [ ! "$IPADDR" = "127.0.0.1" ]; then # set up IP statically:
  # Set up the ethernet card:
  echo "Configuring eth0 as ${IPADDR}..."
  /sbin/ifconfig eth0 ${IPADDR} broadcast ${BROADCAST} netmask ${NETMASK}

  # If that didn't succeed, give the system administrator some hints:
  if [ ! $? = 0 ]; then
    cat << EOF
Your ethernet card was not initialized properly.  Here are some reasons why this
may have happened, and the solutions:
1. Your kernel does not contain support for your card.  Including all the
   network drivers in a Linux kernel can make it too large to even boot, and
   sometimes including extra drivers can cause system hangs.  To support your
   ethernet, either edit /etc/rc.d/rc.modules to load the support at boottime,
   or compile and install a kernel that contains support.
EOF
  fi

  # Older kernel versions need this to set up the eth0 routing table:
  KVERSION=`uname -r | cut -f 1,2 -d .`
  if [ "$KVERSION" = "1.0" -o "$KVERSION" = "1.1" \
   -o "$KVERSION" = "1.2" -o "$KVERSION" = "2.0" -o "$KVERSION" = "" ]; then
    /sbin/route add -net ${NETWORK} netmask ${NETMASK} eth0
  fi

  # If there is a gateway defined, then set it up:
  if [ ! "$GATEWAY" = "" ]; then
    /sbin/route add default gw ${GATEWAY} netmask 0.0.0.0 metric 1
  fi
fi

# End of rc.inet1