On a Dell server, desktop, or laptop running Linux, you can use the following command to find the service tag:
sudo dmidecode -s system-serial-number
This command will display the service tag of your Dell system by reading the system information from the DMI (Desktop Management Interface) table. The dmidecode command is a tool for dumping a computer’s DMI (SMBIOS) table contents in human-readable format.
Note that this command requires sudo privilege as it needs to read the DMI table, which is a privileged operation.