Install PostgreSQL on CentOS 8

Download and install the latest repo RPM from

# dnf install -y

Disable the built-in PostgreSQL module:

# dnf -qy module disable postgresql

Install PostgreSQL:

# dnf install -y postgresql12-server

Optionally initialize the database and enable automatic start:

# /usr/pgsql-12/bin/postgresql-12-setup initdb
# systemctl enable postgresql-12
# systemctl start postgresql-12

Install VirtualBox Additions on CentOS 8

Login as root and install packages required for building kernel modules and elfutils-libelf-devel as a prerequisite for the additions.

# dnf install gcc kernel-devel kernel-headers dkms make bzip2 perl elfutils-libelf-devel

From the VirtualBox window, insert the guest-tools CD image.
Devices -> “Insert Guest Additions CD Image”

Mount the virtual CD-ROM drive and install the VirtualBox Additions.

# mkdir /mnt/cdrom
# mount /dev/cdrom /mnt/cdrom
# cd /mnt/cdrom/
# sh ./ --nox11
# reboot

Fix Samba Error – Failed to setup guest info

When starting samba you may receive this error:

smbd[11632]: ../source3/auth/auth_util.c:1382(make_new_ses...guest)
smbd[11632]:   create_local_token failed: NT_STATUS_ACCESS_DENIED
smbd[11632]: ../source3/smbd/server.c:2000(main)
smbd[11632]:   ERROR: failed to setup guest info.

Read more Fix Samba Error – Failed to setup guest info

How To Determine The Number of CPUs in Linux

  1. Simply use the lscpu command to view the number of CPUs
    # lscpu
    Architecture:        x86_64
    CPU op-mode(s):      32-bit, 64-bit
    Byte Order:          Little Endian
    CPU(s):              4
    On-line CPU(s) list: 0-3
    Thread(s) per core:  1
    Core(s) per socket:  4
    Socket(s):           1
    NUMA node(s):        1
    Vendor ID:           GenuineIntel
    CPU family:          6
    Model:               158
    Model name:          Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz
    Stepping:            9
    CPU MHz:             2807.994
    BogoMIPS:            5615.98
    Hypervisor vendor:   KVM
    Virtualization type: full
    L1d cache:           32K
    L1i cache:           32K
    L2 cache:            256K
    L3 cache:            6144K
    NUMA node0 CPU(s):   0-3
    Flags:               fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx rdtscp lm constant_tsc rep_good nopl xtopology nonstop_tsc cpuid tsc_known_freq pni pclmulqdq ssse3 cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx rdrand hypervisor lahf_lm abm 3dnowprefetch invpcid_single pti fsgsbase avx2 invpcid rdseed clflushopt flush_l1d
  2. Read more How To Determine The Number of CPUs in Linux