IBM AIX Interview Preparation Guide

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An interactive shell generally reads from, and writes to, a user's terminal: input and output are connected to a terminal. Bash interactive behavior is started when the bash command is called upon without non-option arguments, except when the option is a string to read from or when the shell is invoked to read from standard input, which allows for positional parameters to be set.

• AIX uses a hierarchical file tree that consists of directories, subdirectories and files.
• The top level directory is called the root (/) directory that has many subdirectories.
• The file tree is mounted during the system startup.

• To login in:
Login id: <username>
Password: <the password does not appear>
• To log out:
$ <ctrl+d> (or)
$ <exit> (or)
$ logout

• AIX is designed as a multiuser system, a level of security is implemented to control access. Each user of the system has a user name and associated password (optional).
• If the user ID requires a password, the system will prompt for the password in a similar manner. While the user is typing a password, it does not appear on the screen.
• To terminate the session the user may either enter the exit or logout command, or press the key combination <Ctrl-d> (holding down the Ctrl key while pressing the d key.) logout only works if you are in your login shell.

• $ passwd
$ <user id> old password:
$ <user id> new password:
$ Enter the new password again:

• The passwd command is used to change the user password.
• The system will start the passwd process which will prompt the user for their old password first. To prevent users being locked out of the system the new password is entered twice.

• $ command option(s) argument(s)
• Mail –f newmail
• The command or process name should come first.
• The options should follow the command name, separated by a space, and preceded by a minus sign (-). Multiple options may be grouped immediately after a single minus sign or separated by spaces and each preceded by a minus sign.

• AIX is the IBM product.
• It is the multi user Operating System.
• AIX control these hardware devices and to share them between multiple users, for this purpose it uses the AIX Kernel System.
• AIX OS servers are the IBM servers used in all over the world.
• Kernel is loaded during the system startup.
• Kernel is the heart of the AIX OS.
• Kernel controls the various processes and tasks.

• AIX is a multi-user system
• When the user login he needs to provide the user name and password for authentication purposes.
• After the successful login, AIX starts the SHELL program.

• As the user login to the AIX server, the AIX starts the SHELL program.
• The SHELL is a command interpreter.
• It takes the inputs from the users and executes it.
• SHELL is not only the command interpreter it also provide great flexibility to the user.
• SHELL not only read and execute the commands it also read the files written in the form of programs and executes them, these shell program files are known as SHELL scripts. The extension of SHELL script is .sh.

• sh or Bourne Shell
• bash or Bourne Again shell
• csh or C shell
• tcsh or Turbo C shell
• ksh or the Korn shell

• Bash is the GNU shell
• Bash is an sh-compatible shell that incorporates useful features from the Korn shell (ksh) and C shell (csh).


• It is intended to conform to the IEEE POSIX P1003.2/ISO 9945.2 Shell and Tools standard.
• It offers functional improvements over sh for both programming and interactive uses.
• Interactive usage includes command line editing, unlimited size command history, job control, shell functions and aliases, indexed arrays of unlimited size, and integer arithmetic in any base from two to sixty-four. Bash can run most sh scripts without modification.

• $ date
• $ cal
• $ cal 2003 (looking in a year)
• $ cal 1 2003(looking in a month)

• Clear: clears the terminal signal
• $ clear
• echo : Writes what follows to the screen.
• $ echo Lunch is at 12:00
• Lunch is at 12:00
• Banner : Writes character strings in large letters to the screen
• $ banner Hello
• $ print Lunch is at 12:00
• Lunch is at 12:00

• Backspace : to correct mistakes.
• <ctrl+c> : terminates the correct command and return to the shell.\
• <ctrl+d> : end of transmission or end of file
• <ctrl+s> : temporary stops the output to the screen
• <ctrl+q> : resumes output which was stopped by ctrl+s
• <ctrl+u>: erases the entire line.

The man command will look in the on-line manual for information on the commands, subroutines and files with the name title. This information will be presented on the screen one page at a time for the user to browse.
The information consists of:
PURPOSE : The title and a one-line description of the command
SYNTAX : The syntax of the command
DESCRIPTION : Many pages of information about the function and usage of the
command with examples
FLAGS : Description of available options
FILES : Any system files associated with the command
RELATED INFO : The names of any related commands
BUGS : Any information about the behavior/performance of the command in unusual circumstances
$ man <command for which you want the information>

A file is a collection of data, stream of characters or a byte stream. No structure is imposed on the file by OS. The various file types are as follows:
• Ordinary (text or code data)
• Directory (table of contents, that stores a list of files within that directory)
• Special files(representing hardware or logical devices)
An ordinary file can contain either text or code data. Text files are readable by a user and
can be displayed or printed. Code data, also known as a binary file is readable by the
computer. Binary files may be executable. Directories contain information the system needs to access all types of files, but they do not contain the actual data. Each directory entry represents either a file or a subdirectory.Special files usually represent devices used by the system.

AIX(Advanced Interactive executive) is a series of proprietary Unix operating systems developed and sold by IBM for several of its computer platforms. Originally released for the IBM 6150 RISC workstation, AIX now supports or has supported a wide variety of hardware platforms, including the IBM RS/6000 series and later IBM POWER and PowerPC-based systems, IBM System i, System/370 mainframes, PS/2 personal computers, and the Apple Network Server. AIX is based on UNIX System V with 4.3BSD-compatible extensions. It is one of four commercial operating systems that are presently certified to The Open Group's UNIX 03 standard (The others are Mac OS X, Solaris and HP-UX.)

SMIT is the System Management Interface Tool for AIX. It allows a user to navigate a menu hierarchy of commands, rather than using the command line. Invocation is typically achieved with the command smit. Experienced system administrators make use of the F6 function key which generates the command line that SMIT will invoke to complete the proposed task. SMIT also generates a log of commands that are performed in the smit.script file. The smit.script file automatically records the commands with the command flags and parameters used. The smit.script file can be used as an executable shell script to rerun system configuration tasks. SMIT also creates the smit.log file, which contains additional detailed information that can be used by programmers in extending the SMIT system.

The following are some unique system management features of AIX.
☛ Logical Volume Manager :- The Logical Volume Manager (LVM) maintains the hierarchy of logical structures that manage disk storage.
☛ System Resource Controller:- The System Resource Controller (SRC) provides a set of commands and subroutines for creating and controlling subsystems and is designed to minimize the need for human intervention in system processing.
☛ Object Data Manager :- The Object Data Manager (ODM) is a data manager intended for the storage of system data.
☛ Software Vital Product Data:- Certain information about software products and their installable options is maintained in the Software Vital Product Data (SWVPD) database.
☛ Workload management :- Workload Manager (WLM) is designed to provide the system administrator with increased control over how the scheduler virtual memory manager (VMM) and the disk I/O subsystem allocate resources to processes. You can use WLM to prevent different classes of jobs from interfering with each other and to allocate resources based on the requirements of different groups of users.
☛ Operating system updates:- The operating system package is divided into file-sets, where each file-set contains a group of logically related customer deliverable files. Each file-set can be individually installed and updated.

There are two methods for configuring a read/write optical drive. The read/write optical drive must be connected to the system and powered on.

☛ Method 1:-Method one is the faster of the two methods. It only configures the read/write optical drive specified. To use this method, you must provide the following information:
Subclass Defines how the drive is attached.
Type Specifies the type of read/write optical drive.
Parent Name Specifies the system attachment the drive is connected to.
Where Connected Specifies the logical address of the drive.
Enter the following command to configure the read/write optical drive:
mkdev -c rwoptical -s Subclass -t Type -p ParentName -w WhereConnected
The following is an example of a read/write optical drive that has a SCSI ID of 6, a logical unit number of zero, and is connected to the third (scsi3) SCSI bus:
mkdev -c rwoptical -s scsi -t osomd -p scsi3 -w 6,0 -a pv=yes

Method of Configuration Manager, searching the current configuration, detecting any new devices, and automatically configuring the devices. This method is used when little information is known about the read/write optical drive.
a)Use the configuration manager to configure all newly detected devices on the system (including the read/write optical drive) by typing:
cfgmgr
b)Type the following command to list the names, location codes, and types of all currently configured read/write optical drives:
lsdev -C -c rwoptical
c)Determine the name of the newly configured read/write optical drive using the location code that matches the location of the drive being added.

☛ AIX uses a hierarchical file tree that consists of directories, sub-directories and files.
☛ The top level directory is called the root (/) directory that has many sub-directories.
☛ The file tree is mounted during the system start-up.

☛ Backspace : to correct mistakes.
☛ <ctrl+c> : terminates the correct command and return to the shell.
☛ <ctrl+d> : end of transmission or end of file
☛ <ctrl+s> : temporary stops the output to the screen
☛ <ctrl+q> : resumes output which was stopped by ctrl+s
☛ <ctrl+u>: erases the entire line.

To login in:
Login id: <username>
Password: <the password does not appear>
To log out:
$ <ctrl+d> (or)
$ <exit> (or)
☛ AIX is designed as a multiuser system, a level of security is implemented to control access. Each user of the system has a user name and associated password (optional).
☛ If the user ID requires a password, the system will prompt for the password in a similar manner. While the user is typing a password, it does not appear on the screen.
☛ To terminate the session the user may either enter the exit or logout command, or press the key combination <Ctrl-d> (holding down the Ctrl key while pressing the d key.) logout only works if you are in your login shell.

A command is a request to perform an operation or run a program. A process is a program or command that is actually running on the computer.We use commands to tell the operating system what task you want it to perform. When commands are entered, they are deciphered by a command interpreter (also known as a shell), and that task is processed.
The operating system can run many different processes at the same time. The operating system allows you to manipulate the input and output (I/O) of data to and from your system by using specific I/O commands and symbols. You can control input by specifying the location from which to gather data. For example, you can specify to read input entered on the keyboard (standard input) or to read input from a file. You can control output by specifying where to display or store data. For example, you can specify to write output data to the screen (standard output) or to write it to a file.
Commands :- Some commands can be entered simply by typing one word. It is also possible to combine commands so that the output from one command becomes the input for another command.
Processes :- A program or command that is actually running on the computer is referred to as a process.

Server Message Block File system (SMBFS) allows access to shares on SMB servers as local file systems on AIX. In this file system, the user can create, delete, read, write, and modify the access times of files and directories. The owner or access mode of files and directories cannot be changed.