Karunesh Johri

Software developer, working with C and Linux.

Regular Expressions in C

1.0 Introduction Regular expressions are used for searching strings in text files. A regular expression is a string of characters and may contain certain metacharacters. A metacharacter has a special meaning. A regular expression denotes a set of strings. Or, in other words, there is a set of strings that are matched by it. The …

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vi not showing color syntax highlighting in Ubuntu Linux

1.0 Error The vi editor in Ubuntu Linux distribution is not showing color syntax highlighting in the edit window. 2.0 Solution vi is one of the original text editors of the UNIX operating system offering full screen text editing with excellent cursor movement, navigation, search, edit, copy, cut and paste capabilities. The equivalent program under …

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Using sha256sum command for ensuring file integrity

1.0 SHA-2 A cryptographic hash function (CHF) is an algorithm to map arbitrary size data, called the message, to a fixed sized bit array, called the hash value, or message digest. It is a one way function. It is not feasible to generate the original message from the hash value. A small change in the …

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Simple Screen Recorder records only a black screen

1.0 Problem Simple Screen Recorder program records only a blank black screen on Ubuntu Linux. 2.0 Solution The problem is solved with the following steps. Close all programs. Log out. Start a fresh login procedure. Click on the user name. Before entering the password, find the gear icon in the bottom right corner of the …

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Audacity: The cursor is not moving over the waveform during playback

1.0 Problem The cursor does not move over the waveform during playback. It does not update during playback. 2.0 Solution The problem was resolved with the following steps. Close any open Audacity session. Go to the /usr/share/applications directory. Open the file, audacity.desktop, in an editor. Find the line, Exec=audacity %F Replace it with, Exec=env GDK_BACKEND=x11 …

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