Unix Interview questions for testers | Interview questions on unix basic commands

UNIX INTERVIEW QUESTIONS

231. If One Process Is Inserting Data Into Your MySQL Database? How Will You Check How Many Rows Inserted Into Every Second?

Date Posted: 07/02/2012

Ans: “watch” command in UNIX is repeatedly used to execute command provided with specified delay.

232. What Is Ephemeral Port In UNIX?

Date Posted: 07/02/2012

Ans: Ephemeral ports are port used by Operating system for client sockets. There is a specific range on which OS can open any port specified by ephemeral port range.

233. How Do You Find which Remote Hosts Are Connecting To Your Host On A Particular Port Say 10123?

Date Posted: 07/02/2012

Ans: By using netstat command execute netstat -a | grep “port” and it will list the entire host which is connected to this host on port 10123.

234. How Do You Find Which Processes Are Using A Particular File?

Date Posted: 07/02/2012

Ans: By using ls of command in UNIX. It will list down PID of all the process which is using a particular file.

235. What Is The Use Of ‘grep’ Command?

Date Posted: 07/02/2012

Ans: grep’ is a pattern search command. It searches for the pattern, specified in the command line with
appropriate option, in a file(s).
Syntax: grep
Example: grep 99mx mcafile

236.

Ans: There are four possible results from this call:
‘kill()’ returns 0. This implies that a process exists with the given PID, and the system would allow you to
send signals to it. It is system-dependent whether the process could be a zombie.
‘kill()’ returns -1, ‘errno == ESRCH’ either no process exists with the given PID, or security enhancements
are causing the system to deny its existence. (On some systems, the process could be a zombie.)
‘kill()’ returns -1, ‘errno == EPERM’ the system would not allow you to kill the specified process. This means
that either the process exists (again, it could be a zombie) or draconian security enhancements are present
(e.g. your process is not allowed to send signals to *anybody*).
‘kill()’ returns -1, with some other value of ‘errno’ you are in trouble! The most-used technique is to assume
that success or failure with ‘EPERM’ implies that the process exists, and any other error implies that it
doesn’t.
An alternative exists, if you are writing specifically for a system (or all those systems) that provide a ‘/proc’
filesystem: checking for the existence of ‘/proc/PID’ may wWhat is relative path and absolute path.
Absolute path : Exact path from root directory.
Relative path : Relative to the current path may work.

Explain Kill() And Its Possible Return Values?

Date Posted: 07/02/2012

Ans: There are four possible results from this call: ‘kill()’ returns 0. This implies that a process exists with the given PID, and the system would allow you to send signals to it. It is system-dependent whether the process could ...

237. How To Terminate A Process Which Is Running And The Specialty On Command Kill 0?

Date Posted: 07/02/2012

Ans: With the help of kill command we can terminate the process.
Syntax: kill pid
Kill 0 – kills all processes in your system except the login shell.

238. What Is Redirection?

Date Posted: 07/02/2012

Ans: Directing the flow of data to the file or from the file for input or output.
Example : ls > wc

239. What Are Shell Variables?

Date Posted: 07/02/2012

Ans: Shell variables are special variables, a name-value pair created and maintained by the shell.
Example: PATH, HOME, MAIL and TERM

240. How Does The Kernel Differentiate Device Files And Ordinary Files?

Date Posted: 07/02/2012

Ans: Kernel checks ‘type’ field in the file’s inode structure.