The UNIX School

C program to multiply, divide and find reminder for x by 4 without arithmetic operators?

2012-02-09T06:53:00.000-08:00

One of my friends asked me an interesting interview question. The question is like this: How to multiply, divide and find reminder of a number X by 4 without using arithmetic...

join command

2012-01-24T08:07:00.000-08:00

join command is used to join two files based on a key field present in both the files. The input files can be separated by white space or any delimiter. join can be looked at like...

5 different ways to add all the numbers in a file

2011-09-26T06:39:00.000-07:00

In this article, we will see the different ways in which can add or sum up all the contents in a file. Let us take a sample file with the following contents: $ cat file 3 4 5 1. The simplest...

5 useful settings to have in .vimrc for a developer

2011-09-23T04:02:00.001-07:00

In this article, we are going to see some of the most important settings which is mandatory for a developer to have in his .vimrc or .exrc file. set incsearch : When we want to search for...

sed - Selective printing

2011-09-21T09:50:00.000-07:00

In this sed article, we are going to see the different options sed provides to selectively print contents in a file. Let us take a sample file with the following contents: $ cat...

awk - Passing arguments or shell variables to awk

2011-09-13T06:34:00.000-07:00

In one of our earlier articles, we saw how to read a file in awk. At times, we might have some requirements wherein we need to pass some arguments to the awk program or to access a shell...

5 different ways to join all lines in a file

2011-08-30T07:48:00.000-07:00

In one of our earlier articles, we saw how to fold a file using the fold command. In this article, we will see the different ways in which we can unfold the file, or in other words, different...

Fold files using fold command

2011-08-25T07:17:00.000-07:00

It is possible at times we need to read a file which is not organized in the normal way. We are used to reading files which is line sequential meaning every record is present in a line....

A Shell Script to do shell scripting faster

2011-08-18T07:52:00.000-07:00

Shell Scripting is all about automating a particular task, doing a task a bit faster than what it takes to do manually. However, when we write a shell script, if we notice properly, the...

What is a profile file?

2011-07-28T08:01:00.000-07:00

A profile file is a start-up file of an UNIX user, like the autoexec.bat file of DOS. When a UNIX user tries to login to his account, the operating system executes a lot of system...

5 important things to follow to become good in shell scripting

2011-07-25T09:00:00.000-07:00

Everybody wants solutions to their problems, and more importantly, we are now expected to get it faster. One can give faster solutions in Unix when one has a good...

Difference between $x and ${x}

2011-07-04T06:42:00.000-07:00

Many times in shell scripts we would have witnessed two different forms of notations being used against variables: $x and ${x}. Are they both same or is there any difference...

3 different ways of dumping hex contents of a file

2011-06-30T07:27:00.000-07:00

At times, when you are doing any conversion of ascii to hex or to octal, we would like to view the hex contents or the hex dump of the file, be it ascii or binary. Let us see in this article...

3 different time stamps associated with a file in Unix

2011-06-28T08:29:00.000-07:00

Any file present or created in Unix has 3 different time stamps associated with it . The 3 different timings are: 1. Last modified time - This refers to the timing when the file has been...

Inode - All about inodes

2011-06-21T07:02:00.000-07:00

Everything is a file in Unix, we say. Users deal with files a lot, however, we usually can get most of our work done without needing to know about i-nodes, and their relation with files....

5 different ways to do numbering of a file contents

2011-06-15T08:21:00.000-07:00

Sometimes, we might have a requirement wherein we need to display the file contents with its line number. In this article, we will see the different ways in which we can achieve this line...

cut - cut files with a delimiter

2011-05-31T08:29:00.000-07:00

cut is a very frequently used command for file parsing. It is very useful in splitting columns on files with or without delimiter. In this article, we will see how to use the cut command...

awk - Read a file and split the contents

2011-05-24T06:22:00.000-07:00

awk is one of the most powerful utilities used in the unix world. Whenever it comes to text parsing, sed and awk do some unbelievable things. In this first article on awk, we will see the basic...

bc - Unix calculator

2011-05-17T06:50:00.000-07:00

Whenever we need to do some calculation, we open the calculator in the windows. For unix programmers, why to go for windows calculator when we have an in-built one, bc. bc is a unix...

sed - Read from a file or write into a file

2011-04-05T08:01:00.000-07:00

In this sed article, we will see how to read a file into a sed output, and also how to write a section of a file content to a different file. Let us assume we have 2 files,...

Different ways to add header and trailer line to a file

2011-03-28T06:48:00.000-07:00

In this article, we will see the different ways to add a header record or a trailer record to a file. Let us consider a file, file1. $ cat file1 apple orange grapes banana 1. To...

Different ways to delete ^M character in a file

2011-03-17T08:32:00.000-07:00

Control-M is a character found at the end of a line usually in files transferred from windows. Before, processing these files in UNIX, we need to remove the ^M characters. Let us see in this...

comm - The beautiful comparison

2011-03-15T08:21:00.000-07:00

comm is one of the most underused commands in UNIX. I have seen many times programmers resorting to writing a shell script to achieve something which comm could have done it easily. Let us...

Oracle 10g Express: How to set up Oracle XE?

2011-03-10T08:47:00.000-08:00

Oracle XE is a Oracle Express edition Oracle software provided by Oracle. This software allows developers to install Oracle in their computer and practice Oracle and PL/SQL. Steps for...

Difference between $* and $@ in Shell

2011-03-08T08:36:00.000-08:00

In one of our earlier articles, we saw the different positional parameters in a shell script. We discussed about the positional parameter $*. There is one more positional parameter, $@, the...