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201. What Are Pttys?
Date Posted: 07/02/2012
Ans: Pttys are also called as Pseudo-teletypes, these are pseudo-devices that consist of two parts, which are as follows: 1st is the master side, which can be considered as “user” and 2nd is the slave side, which acts like standard tty device. They allow means to emulate the behavior of serial terminal using the control of the program. Example of this is as follows: telnet uses pseudo terminal on remote system.
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202. How Can Multiple Processes Write To The Pipe Simultaneously?
Date Posted: 07/02/2012
Ans: Multiple processes can be written to pipe simultaneously by the use of PIPE_BUF. The conditions which have to be noted down is that, if the data to be written to the pipe is less than PIPE_BUF then, the data won’t be interleaved. The read call at the same time will return all the data present, even from the multiple writes. PIPE_BUF size is at least 512KB. It is defined in “<limits.h>.
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203. What Is The Difference Between Internal And External Commands?
Date Posted: 07/02/2012
Ans: Internal commands are commands that are already loaded in the system. They can be executed any time and are independent. On the other hand, external commands are loaded when the user requests for them. Internal commands don’t require a separate process to execute them. External commands will have an individual process. Internal commands are a part of the shell while external commands require a Path. If the files for the command are not present in the path, the external command won’t execute.
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204. What Is The Difference Between Home Directory And Working Directory?
Date Posted: 07/02/2012
Ans:
Home Directory: Every user will have one home directory and will have complete control over it. On login, home is the default working directory for the user. It contains the configuration files and responsible for login and logout of the user.
Working directory: The directory in which the user is working currently is known as working directory. The home may also be the working directory, if the user is working in it.
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205. What Is LILO?
Date Posted: 07/02/2012
Ans: LILO is Linux Loader is a boot loader for Linux. It is used to load Linux into the memory and start the Operating system. LILO can be configured to boot other operating systems as well. LILO is customizable, which means that if the default configuration is not correct, it can be changed. Config file for LILO is lilo.conf
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206. What Is Linux And Why Is It So Popular?
Date Posted: 07/02/2012
Ans: Linux is an operating system that uses UNIX like Operating system. However, unlike UNIX, Linux is an open source and free software. Linux was originally created by Linus Torvalds and commonly used in servers.
Popularity of Linux is because of the following reasons
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It is free and open source. We can download Linux for free and customize it as per our needs.
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It is very robust and adaptable.
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Immense amount of libraries and utilities
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207. How To Find Some Particular Lines In Unix Vi Editor Which Starts With A Particular Word And End With Another Particular Word?? For Ex - There Are 10 Lines In The Editor And Only 4 Lines Start With The Word APPLE And End With The Word MANGO. Now How To Find Out These Particular Lines In UNIX?
Date Posted: 07/02/2012
Ans:
1.Esc
2. :
3. APPLE*
4. *MANGO
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208. How Do You Create A Decision Tree In A Shell Script?
Date Posted: 07/02/2012
Ans: It depends on shell, usually a case-esac or an if-end if or if structure.
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209. How Many Prompts Are Available In A UNIX System
Date Posted: 07/02/2012
Ans: Unix/ Linux Supports four Prompts PS1, PS2, PS3, PS4.
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210. UNIX Command To Concatenate (attach) Two Strings?
Date Posted: 07/02/2012
Ans: cat $str1 $str2 is WRONG - cat command will need file names as input
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