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UNIX Commands Filesystem Networking Process Permissions Devices Errors LVM

What is UNIX?

UNIX is a multiuser and multitasking operating system widely used in enterprise environments. AIX, Solaris and HP-UX are UNIX operating systems mainly used for critical production workloads.

AIX is developed by IBM for IBM Power Servers.

AIX mainly runs on IBM Power Servers and is widely used for banking, SAP, Oracle and enterprise production workloads.

Operating System Types

Windows 11
MacOS
Linux (RHEL, Ubuntu, Rocky Linux)
UNIX (AIX, Solaris, HP-UX)
BSD (FreeBSD, NetBSD)

AIX Operating System

AIX is an enterprise UNIX operating system developed by IBM.

It is mainly used for: 

1. Production Databases
2. Enterprise Applications
3. Banking Systems
4. SAP Workloads
5. Oracle Databases
6. High Availability Systems

Virtualization Concepts

Virtual Machine = LPAR

HMC = Hardware Management Console

VIOS = Virtual I/O Server

LPAR Resources:
- vCPU
- RAM
- DISK
- Network

Important Basic Commands

oslevel -s
uptime
who -b
last
who
pwd
which grep

oslevel -s displays AIX Version, Technology Level and Service Pack.

Filesystem Structure

/       = Root directory
/usr    = Program binaries
/var    = Logs and variable files
/tmp    = Temporary files
/home   = User home directory
/proc   = Process information
/opt    = Third party applications

Basic Networking Commands

ifconfig -a
netstat -rn

mktcpip

chdev -l en0 -a netaddr=10.1.1.1

Process Management

ps -ef
lssrc -a
startsrc -s sshd
stopsrc -s sshd
kill PID

UNIX Permissions

r = read
w = write
x = execute

u = user
g = group
o = other

-rwxr-xr-x

User Management

mkuser testuser
lsuser testuser
rmuser testuser

AIX Version Structure

AIX version contains Version, Technology Level (TL), Service Pack (SP) and build date information. 

7200-05-10-2520

7200 = AIX 7.2
05   = Technology Level 5
10   = Service Pack 10
2520 = Year 2025 Week 20

LPAR Architecture

IBM Power Systems use virtualization through LPARs (Logical Partitions). 

Physical Server
   |
   |--- HMC
   |
   |--- VIOS
          |
          |--- LPAR1
          |--- LPAR2
          |--- LPAR3

HMC manages CPU and memory resources. VIOS manages storage and network virtualization.

System Information Commands

prtconf
lparstat
vmstat
topas
nmon

These commands are used to monitor: CPU, memory, virtualization, performance and workload.

Process Types

Parent Process
Child Process
Zombie Process
Orphan Process

Zombie process means terminated process whose entry still exists in process table.

Device Management in AIX

In AIX, everything is treated as a device. All device information is stored in ODM. 

ODM = Object Data Manager

Network Device  = ent0
Disk Device     = hdisk0
Fiber Device    = fcs0
Virtual SCSI    = vscsi0

Device Information Commands

lsdev -Cc adapter
lsattr -El ent0
lscfg -vl ent0
entstat -d ent0

These commands help administrators view device configuration and hardware details.

Error Handling in AIX

Always investigate hardware related errors immediately because disk and fiber errors may cause production outages. 
errpt
errpt -a
errpt -aj IDENTIFIER

AIX stores hardware and software errors inside error log repository. 

FE2DEE00

DUPLICATE IP ADDRESS DETECTED

Filesystem Commands

lsfs
crfs
chfs
rmfs
mount
umount

JFS2 is the default filesystem used in AIX.

AIX LVM Concepts

PV = Physical Volume
VG = Volume Group
LV = Logical Volume
PP = Physical Partition
FS = Filesystem

LVM is used to manage disks, storage pools and filesystems in AIX.

Important Networking Commands

ifconfig -a
netstat -rn
mktcpip
smitty tcpip

These commands are used for IP configuration and troubleshooting.

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