I want to write a script that will achieve the same effect as changing the hostname in raspi-config. However, I am not entirely sure what raspi-config does when the hostname is changed (via 1 System Options > S4 Hostname).
I assume that at least the following two changes are made:
/etc/hostname is changed127.0.1.1 in /etc/hosts is changedIs there any other change made?
It would indeed appear that it is in just those two files that changes are made.
Looking at line 216 of the source code for the script:
echo $NEW_HOSTNAME > /etc/hostname
sed -i "s/127.0.1.1.*$CURRENT_HOSTNAME/127.0.1.1\t$NEW_HOSTNAME/g" /etc/hosts
As you have noted 2 files are changed.
I routinely edit these; I have a script which I run if swapping a SD Card between Pi.
#!/bin/bash
# script to set Pi hostname based on Serial number
# 2021-04-17
# This script should be run as root (or with sudo) to change names
# If run by a user it will report changes, but will NOT implement them
PDIR="$(dirname "$0")" # directory containing script
CURRENT_HOSTNAME=$(hostname)
CPUID=$(awk '/Serial/ {print $3}' /proc/cpuinfo | sed 's/^0*//') #Pi4 has 16digit serial with leading '1'
CPUID=$(awk '/Serial/ {print $3}' /proc/cpuinfo | cut -c9-)
echo "Current Name" $CURRENT_HOSTNAME
echo "CPUID" $CPUID
If you want to specify hostnames create a file PiSerialNo.txt with SerialNo hostname list e.g.
e9195b37 MyPi
If not found a unique Name based on SerialNo number will be set
NEW_HOSTNAME=$(awk /$CPUID/' {print $2}' $PDIR"/PiSerialNo.txt")
echo "Name found" $NEW_HOSTNAME
if [ -z $NEW_HOSTNAME ]; then
NEW_HOSTNAME="pi"$CPUID
fi
if [ $NEW_HOSTNAME = $CURRENT_HOSTNAME ]; then
echo "hostname $NEW_HOSTNAME already set"
else
if [ $(id -u) -ne 0 ]; then
echo "Please run with sudo to change name"
exit
fi
echo "Setting Name" $NEW_HOSTNAME
echo $NEW_HOSTNAME > /etc/hostname
sed -i "/127.0.1.1/s/$CURRENT_HOSTNAME/$NEW_HOSTNAME/" /etc/hosts
fi
hostnamefor the first part, it has a man page that may be interesting. – goldilocks Oct 16 '22 at 17:56