AIX Basic Interview Questions 2

AIX Basic Interview Questions

1. How will you list the users who are currently logged in?

Ans: who, finger, f

2. How will you get the login and log out time?

Ans: last

3. What are the fields in /etc/passwd?

Ans: Uname,Password Attribute,User ID,Group ID,Gecos,Home Directory,Login Shell

4. What is * and !  Symbols indicate in /etc/passwd fields?

Ans: * indicates that account is not activated,! Indicates that passwd has been assigned and the account is activated.

5. How can u change the shell for the particular user?

Ans: $HOME/.profile

6. How can u change the root shell prompt?

Ans: ps1=”shell_name”

7. How to make a PV available?

Ans: chdev -l hdisk2 -a pv=yes

8. How to list lv's in rootvg, what is the output of opened/syncd, closed/syncd and open/stale?

Ans: lsvg -l rootvg, Indicates the LV state for the lv's. Open/stale indicates the logical volumes is opened but contains partitions that are not current. Opened/syncd opened and synchronized. Closed/syncd not opened and synchronized.

9. Tell about Performance Monitoring?

Ans: topas, svmon, vmstat, iostat, netstat, sar ,entstat, lvmstat, lparstat, lpstat.

10. How can we get the Network Statistics?

Ans: netstat. ifconfig

11. How can u get the OS name?

Ans: uname

12.  How can u get the OS Version?

Ans: uname -v

13. How to list the Paging Space?

Ans: lsps -a

14. What is meant by Patches?

Ans: Its a fix for the problems that are encounter currently. Eg: APAR

15. What is the difference between inittab and crontab?

Ans: inittab is used for System Initialization and crontab is used for Scheduling.

16. Tell about boot process?

Ans: POST, System ROS, Software ROS, Kernel Initialization, 3 phases of booting.

17. What is the role of cfgmgr in boot devices?

Ans: It configures base devices and non-base devices.

18. How to refresh the inittab?

Ans: It automatically refresh for every 60 seconds.

19. How to check the maintenance level and technology level?

Ans: oslevel -r

20. How to increase File System size?

Ans: chfs -a size=+10  -m /doli

21. How to go the end of the file in vi Editor?

Ans: shift+g (caps G)

22. What is ODM?

Ans: ODM is a repository which stores the operating system related information such as interfaces, softwares, tcpip configuration.

23. What is mirrorvg?

Ans: mirrorvg command is used to mirror data from one PV to another PV in the same VG.

24. What are the Components of LVM?

Ans: Volume Group, Physical Volume, Physical Partition, Logical Volume, Logical partition.

25. How to check the available size of the PV in VG and migration of PV?

Ans: lspv hdisk0, migratepv sourcepv destinationpv eg: migratepv hdisk0 hdisk1

26. What is the use of Telinit?

Ans: It is used to set the runlevel.

27. Which command to list active vg?

Ans: lsvg -o

28. How to view the run level?

Ans: who -r, cat /etc/.init.state

29. How will u create the user?

Ans: mkuser username, mkuser -a username (for admin)

30. What are the changes will occur while creating a user?

Ans: /etc/security/user, etc/security/limits, /etc/security/environ, etc/passwd.

31. How will you specify the big vg?

Ans:  mkvg -B -y vgname -s 128 hdisk0

32. How will u view the  modified  time of a file?

Ans: ls -lt

33. What is quorum?

Ans: It is used to maintain the data integrity of a particular vg. Used for retrieving data.

35. How will u change the runlevel?

Ans: Telinit.

36. What is page in and page out?

Ans: Page in: Moving the process or data from the real memory to the virtual memory in the hard disk.

Page out: Moving the process or data from the virtual memory to the real memory.

38. How will u list the active users?

Ans: who

39. Who -r

displays the run level and who -b last system start up time.

40. What is the use of tar command?

Ans: It is used to copy  and retrieve files into the archive and out of the archives.

42. How to monitor the file growth?

Ans: By impleming the quota using quotaon command.

43. What is quota and how to work with quota?

Ans: It is an effective way to control the use of disk space. Using quotaon command we can enable the quota for a particular file system or for a particular user.

Eg: 1. chfs -a “quota=userquota” /home

quotaon -u /usr/Tivoli/tsm/server/db

44. How to increase or decrease the quota?

Ans:Using edquota command.

45. In which phase /etc/inittab is used?

Ans: Third phase

How to view the real memory size?

Ans: bootinfo -r, prtconf -m

What are the daemons for the Nfs?

Ans:rpc.mountd, biod, nfsd, rpc.statd, rpc.lockd.

What is the cron daemon?

Ans: It is a power scheduler and a long running background process which is used to execute a job periodically.

50. What is the use of “i” flag in mksysb command?

Ans: i flag is for ./image file which is used to collect the information about the filesystems, logical volumes, mount point of the rootvg which is being backed.

How to change the 32 bit kernel to 64 bit kernel?

Ans: # ln -sf /usr/lib/boot/unix_64

# ln -sf /usr/lib/boot/unix_64 /usr/lib/boot/unix

# bosboot -ad /dev/ipldevice

52. What is the use of uname -v and oslevel command?

Ans: To find the version of the os we are using uname -v and to see the version. Release.modification.fix we are using oslevel command.

53. What is zombie process?

Ans: It is a dead process that is no longer executing but still recognized in process table. It is also known as defunct.

How to display the files of size larger than 50MB in /usr?

Ans: find /usr -size 50M -print.

55. Cpu performance monitoring command?

Ans: Topas, Sar

56. How to increase the size of the file system?

Ans: chfs -a size = +10M -m/doli

57. How to give write permission for the file which has been mounted?

Ans: While using the mount command specify the rw permission.

58. How to get help if there is no man page?

Ans: Smit can be used.

59. How to increase the paging space?

Ans: chps command

How to troubleshoot if the system is too slow?

Ans: Kill the unwanted process which consumes the cpu resources using ps command.

What is the output for iostat?

Ans: cpu statistics, i/o statistics of entire system, disks, tapes and file systems.

62. What is the use of mkuser, lsuser and how to list the groups?

Ans: mkuser command is used to create normal user accout or admin, lsuser lists the user account attributes and to list the group use the command lsgroup.

63. What is use of extendlv command?

Ans: it is used to add the logical partitions to the existing Logical volume.

64. How to extend the user space quota?

Ans: edquota command can be used to extend the user space.

65. What is the last step in booting process?

Ans: LED displays are turned off and the init process will continue to the next command in the /etc/inintab.

66. How to list the logical volumes?

Ans: lslv

67. What is the use of skulker command?

Ans: To delete the temporary files in the file systems.

68. Tell me about the AIX installation steps?

Ans:

69. How will you create the file systems?

Ans: crfs -v type of file systems -g rootvg -a size =10M -m /fs1

70. Difference between crontab and init tab?

Ans: Crontab is used to schedule the jobs and init tab will contain the entry for the commands that has to be executed.

71. Can we create a filesystem directly?

Ans: File systems can  also be without creating LV.

72.Types of file systems?

Ans: jfs, jfs2, cdrfs, nfs

73.Difference b/w at and crontab?

Crontab u can schedule lot of process for any time.But using at command only one process to be schedule.at is an temporary but crontab for permanent process.

74. What is the command to list the pv?

Ans: lspv

75. What are all the pv state?

Ans: active, missing, removed.

  76. What is the crontab and how will u do scheduling?

Ans: Cron tab is used for scheduling the jobs and for scheduling we can use crontab -e command.

77. If the size of the file system is not able to change? Troubleshoot the issue?

Ans: May be the quota is turned on for that file system.

78. How will u mirror the Logical volume?

Ans: Using mklvcopy command.

81. What is SUID, SGID, sticky bit?

Ans: SUID is used to set user id for a particular file so that, that particular can access that file. It is inheriting the power of the super user.

SGID: SGID is used to set the group id so that every one in the group can access that file.

Sticky bit: Sticky bit is an access right flag used to set permissions for the so that no other user can rename or delete that file.

82. Quorum

Ans : The minimum number of nodes that must be running in order for the GPFS daemon to start.

Mirroring vg

Ans : # mirrorvg vgname

Difference between JFS and JFS2

 

Function	JFS	JFS2
Architectural maximum file system size	1 TB	4 PB
Architectural maximum file size	64 GB	4 PB
Number of i-nodes	Fixed	Dynamic
Inode size	128 bytes	512 bytes
Fragment size	512	512
Block size	4096	4096
Directory organization	Linear	B-tree
Compression	Yes	No
Default ownership at creation	sys.sys	root.system
SGID of default file mode	SGID=on	SGID=off
Quotas	Yes	Yes

What is mean by JFS

Ans : This type of file system is named journaled because the system uses     journaling techniques to maintain the integrity of control structures.

Each journaled file system must reside on a distinct jfs logical volume.

The file system size will be a multiple of the size of a logical partition.

How can you take a backup of file and give syntax?

Ans : The backup command backs up files and file systems.

Eg: To back up all the files in the / (root) file system that have been modified since the last level 0 backup, enter:

# backup    -1 -u -f /dev/rmt0 /

How will take a backup rootvg

Ans : #mksysb –i

What u mean by rmt0

Ans: Tape drive

How can you retrieve the error record from error log

Ans: #errpt

Path of error log

Ans: /var/adm/ras/errlog

LED 201

Ans : Damaged Boot image

How can list the h/w errors

Ans: #diag

How will you list the s/w which are installed in AIX

Ans : #lslpp

Run levels

Ans : A run level is a software configuration that allows only a selected group of processes to exist.

What you mean by oslevel

Ans : oslevel is the command to know Version,Release,Maintenance,Fixlevel

How can you get the login and logout time

Ans : #last

Can u mirror the lv, if yes means what is the command

Ans : Yes, Using mklvcopy command.

 Using mklvcopy we can create and synchronize extra copies of logical partitions

If you enters the command but you cannot get the output what is the problem

Ans : Check the command and its flag.

           Check whether that commands fileset is installed or not.

What is mean by alog

Ans : alog is a file which contains the error log happen during booting process.

          Path : /var/adm/ras/bootlog

 

/etc/passwd fields

Ans : name:passwd:userid:pgrp:gecos:homedir:shell

How to display the environment variables

Ans : #env or #printenv

What is the difference between du and df

Ans : du summarizes disk usuage.

          Displays the number of blocks used for files.

          du command uses the files in the current directory.

 

 df reports information about space on file systems.

 Displays information about total space and available space on file system

How to activate the 64 bit kernel

Ans :   There are two kernels available in the /usr/lib/boot directory:

          unix_mp     32-bit kernel for multiprocessor systems

          unix_64     64-bit kernel for 64-bit processor systems

The following example provides the commands to run to enable the 64-bit kernel

after system installation:

# ln -sf /usr/lib/boot/unix_64 /unix

# ln -sf /usr/lib/boot/unix_64 /usr/lib/boot/unix

# bosboot -ad /dev/ipldevice

bosboot: Boot image is 23137 512 byte blocks.

# shutdown -r

After the system has rebooted, it will be running the 64-bit kernel.

To reactivate the 32-bit kernel, follow the same procedure, substituting unix_mp for unix_64, depending on your system type.

To verify your settings, execute the following command:

# ls -al /unix

lrwxrwxrwx    1 root    system  21 Nov 11 11:30 /unix -> /usr/lib/boot/unix_64

What is the purpose of sudo

Ans : To inherit the power of super user to execute a particular command.

How can we untar the tar file

Ans : tar –xvf  path/file name

How can we clear the error log details

Ans : #errclear

Difference between error log and errpt

Ans : errlog : writes error log entry to /dev/error file.

                       errlog subroutine is used by application programs.

          errpt : generates error report from entries in error log.

                     Doesn’t perform error log analysis.         

                  

How to remove the failed hdisk in a vg if it mirrored

inode and it’s information

Ans : The inode contains control information about the file, such as type, size, owner, and the date and time when the file was created, modified, or last accessed.

It also  contains pointers to data blocks that store the actual data of the file.

Every file has a corresponding inode.

#ls –i

          Displays inode number for all files.

#istat /usr/bin/ksh

  

/etc/host file details

Ans : This file contains the hostnames and their address for hosts in the network.

           This file is used to resolve a hostname into an internet address.

File Format is,

Internet Address   Hostname             #Comments

How to refresh the services

Ans : #refresh –s service_name

  Where the super block copies are maintained

Ans : 31^st block

How can u retrieve the super block if the super block gets corrupted

Ans : using dd command we can restore,

How will you increase and decrease the paging space

Ans : #chps –s pagingspace_name à increase

          #chps –d pagingspace_name à decrease

How to check the IP address.

Ans : #ifconfig –a

What are the details contain in ifconfig

How to check the system information

Ans : #lscfg –vps | more

How to check the device details

Ans : #lscfg device_name

What is mean by patches?

Ans : ptf and apar are the patches.

Can we set the alias IP to the Ethernet and how?  

Ans : Through the ifconfig command we can bind multiple network addresses to a single network interface by defining an alias.  To bind an alias to a network interface, run the command:

#ifconfig Interface Address [netmask Netmask] alias

example:

#ifconfig tr0 10.1.2.3 netmask 255.255.255.0 alias

Is it retain the alias IP after restarting the system

Ans : yes, the system retain the alias IP address after restarting the system, if we want to remove the alias IP give like

#ifconfig tr0 10.1.2.3 netmask 255.255.255.0 delete

 If you do not specify which alias to be removed from a network interface, the system will default and remove the primary network address from the interface.

In how many ways we will check the os Version?

Ans : #oslevel

 #uname –v

How to list the hard Disks details

Ans : #lspv pvname

   for eg: #lspv hdisk0

How to check the CPU activities?

Ans : By using lot of performance monitoring tools we can check the cpu activities. Some important commands are topas, iostat and sar.

How to check the routing table?

Ans : #netstat -r      (or)

#netstat –nr

Client important files and parameter

opt file contents

 Ans : Opt contains third party deails.

How to check the server name in client side

How to up the interface

Ans : To activate the network interface run the command

    #ifconfig Interface [Address] [netmask Netmask] up          (or)

    #ifconfig Interface up

How to check the default gateway

Ans : #netstat -rn   

What is VGDA

Ans : The volume group descriptor area (VGDA) is an area on the disk that contains information pertinent to the volume group that the physical volume belongs to. It also includes information about the properties and status of all physical volume and logical volumes that are part of the volume group. The information from VGDA is used and updated by LVM commands. There is at least one VGDA per physical volume. TheVGDA internal architecture and location on the disk depends on the type of the volume group.

Types of the VG

   Ans :

Normal VG

Big VG

Scalable VG

How can you list the pv’s?

Ans : #lspv