How to Get CPU Serial Under Linux Without Root Permissions

Extract the Linux serial number without sudo

dmidecode reads this information from physical memory, using /dev/mem, which requires root.

The same information is also provided by the Linux kernel via sysfs in a virtual directory, /sys/devices/virtual/dmi/id.

Unfortunately, someone decided that all information in that virtual directory is open to anyone for reading, just not the serial numbers:

$ ls -l /sys/devices/virtual/dmi/id

-r--r--r-- 1 root root 4096 Nov 25 17:12 bios_date
-r--r--r-- 1 root root 4096 Nov 14 14:59 bios_vendor
-r--r--r-- 1 root root 4096 Nov 25 17:12 bios_version
-r--r--r-- 1 root root 4096 Nov 25 17:12 board_asset_tag
-r--r--r-- 1 root root 4096 Nov 25 17:12 board_name
-r-------- 1 root root 4096 Nov 25 17:12 board_serial
-r--r--r-- 1 root root 4096 Nov 14 14:59 board_vendor
-r--r--r-- 1 root root 4096 Nov 25 17:12 board_version
-r--r--r-- 1 root root 4096 Nov 25 17:12 chassis_asset_tag
-r-------- 1 root root 4096 Nov 25 17:12 chassis_serial
-r--r--r-- 1 root root 4096 Nov 25 17:12 chassis_type
-r--r--r-- 1 root root 4096 Nov 25 17:12 chassis_vendor
-r--r--r-- 1 root root 4096 Nov 25 17:12 chassis_version
-r--r--r-- 1 root root 4096 Nov 25 17:12 modalias
drwxr-xr-x 2 root root    0 Nov 25 17:12 power
-r--r--r-- 1 root root 4096 Nov 14 14:59 product_name
-r-------- 1 root root 4096 Nov 25 17:12 product_serial
-r-------- 1 root root 4096 Nov 14 14:59 product_uuid
-r--r--r-- 1 root root 4096 Nov 14 14:59 product_version
lrwxrwxrwx 1 root root    0 Nov 14 14:59 subsystem -> ../../../../class/dmi
-r--r--r-- 1 root root 4096 Nov 14 14:59 sys_vendor
-rw-r--r-- 1 root root 4096 Nov 14 14:59 uevent

If you can install package hal (not installed by default on recent Ubuntu versions), this command will work for you as non-root:

 lshal | grep system.hardware.serial

 system.hardware.serial = '<serial_number>'  (string)

This works because package hal installs the hald daemon, which runs as root and collects this data, making it possible for lshal to read it as non-root.

c program for linux, to get a serial number of the device, for a non-root user

Why don't you use the MAC address as unique computer id. Here is the code to get MAC address of one of the interface. The code below basically reads name of all the available interfaces and then loops through them to get the MAC address of the first one excluding the loopback interface.

int main()
{
struct ifreq ifr;
struct ifconf ifc;
char buf[1024];
int success = 0;

int sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
if (sock == -1) { /* handle error*/ };

ifc.ifc_len = sizeof(buf);
ifc.ifc_buf = buf;
if (ioctl(sock, SIOCGIFCONF, &ifc) == -1) { /* handle error */ }

struct ifreq* it = ifc.ifc_req;
const struct ifreq* const end = it + (ifc.ifc_len / sizeof(struct ifreq));

for (; it != end; ++it) {
    strcpy(ifr.ifr_name, it->ifr_name);
    if (ioctl(sock, SIOCGIFFLAGS, &ifr) == 0) {
        if (! (ifr.ifr_flags & IFF_LOOPBACK)) { // don't count loopback
            if (ioctl(sock, SIOCGIFHWADDR, &ifr) == 0) {
                success = 1;
                break;
            }
        }
    }
    else { /* handle error */ }
}

unsigned char mac_address[6];

if (success) memcpy(mac_address, ifr.ifr_hwaddr.sa_data, 6);
}

How to read HD serial in Linux without root privileges?

By just listing /dev/disk/by-id/ directory, you get IDs of all block devices on your system. The output is not exactly the same as with the commands, but it is close enough.

For this, you do not need root privileges.

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On my PC :

$ /sbin/udevadm info --query=property --name=sda | grep "ID_SERIAL"
ID_SERIAL=WDC_WD5000AAKX-60U6AA0_WD-WCC2EHJ93860
ID_SERIAL_SHORT=WD-WCC2EHJ93860

and

$ ll /dev/disk/by-id/ | grep sda
lrwxrwxrwx 1 root root   9 Nov 11 07:47 ata-WDC_WD5000AAKX-60U6AA0_WD-WCC2EHJ93860 -> ../../sda
lrwxrwxrwx 1 root root  10 Nov 11 07:47 ata-WDC_WD5000AAKX-60U6AA0_WD-WCC2EHJ93860-part1 -> ../../sda1
lrwxrwxrwx 1 root root  10 Nov 11 07:47 ata-WDC_WD5000AAKX-60U6AA0_WD-WCC2EHJ93860-part2 -> ../../sda2
lrwxrwxrwx 1 root root  10 Nov 11 07:47 ata-WDC_WD5000AAKX-60U6AA0_WD-WCC2EHJ93860-part3 -> ../../sda3

On Linux get disk space used per user when you are not root

You can't determine the size of directories you have no read/execute permissions for, so this is only possible when being root.

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