UNIX Interview Questions/FAQs for Oracle DBAs

Interview Questions

1. What’s the difference between soft link and hard link?
A symbolic (soft) linked file and the targeted file can be located on the same or different file system while for a hard link they must be located on the same file system, because they share same inode number and an inode table is unique to a file system, both must be on the same file system.

2. How you will read a file from shell script?
while read line
echo $line
done < file_name

3. What’s the use of umask?
Will decide the default permissions for files.

4. What is crontab and what are the arguments?
The entries have the following elements:
field             allowed values
—–             ————–
minute            0-59
hour                0-23
day of month   1-31
month             1-12
day of week     0-7 (both 0 and 7 are Sunday)
user                 Valid OS user
command         Valid command or script

? ? ? ? ? command
|  | |  | |_________day of the week (0-6, 0=Sunday)
|  | |  |___________month (1-12)
|  | |_____________day of the month (1-31)
|  |_______________hour (0-23)
|_________________minute (0-59)

5. How to find operating system (OS) version?
uname –a

6. How to find out the run level of the user?
uname –r

7. How to delete 7 days old trace files?
find ./trace –name *.trc –mtime +7 –exec rm {} ;

8. How to get 10th line of a file (by using grep)?

9. (In Solaris) how to find out whether it’s 32bit or 64bit?

10. What is paging?

11. What is top command?
top is a operating system command, it will display top processes which are taking high cpu and memory.

12. How to find out the status of last command executed?

13. How to find out number of arguments passed to a shell script?

14. What is the default value of umask?

15. How to add user in Solaris/Linux?
useradd command