tr is an UNIX utility for translating, or deleting, or squeezing repeated characters. It will read from STDIN and write to STDOUT.

tr stands for translate.
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Loops are very basic and very useful programming facility that facilitates programmer to execute any block of code lines repeatedly and can be controlled as per conditions added by programmer. It saves writing code several times for same task.
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Every file in Linux is associated with timestamps, which specifies the last access time, last modification time and last change time.

Whenever we create a new file, or modify an existing file or its attributes, these timestamps will be updated automatically.

Touch command is used to change these timestamps (access time, modification time, and change time of a file).
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GCC Compiler is a very powerful and popular C compiler for various Linux distributions. This article explains some of the popular GCC compiler options.
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Network tools like wireshark, tcpdump, etc, are fairly popular for packet sniffing. This article provides a basic overview of the libpcap library which forms the base of packet sniffing for many network monitoring tools including wireshark, tcpdump, snort, etc.
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GnuPG stands for GNU Privacy Guard.

GnuPG is an open implementation of OpenPGP ( Pretty Good Privacy ) standard as defined in RFC 4880. In this article we will cover the installation and the basics of generating keys using gnupg.
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Bitwise operators are used to manipulate one or more bits from integral operands like char, int, short, long. In this article, we will see the basics of bitwise operators, and some useful tips for manipulating the bits to achieve a task. This article assumes that you know the basics of Truth Table for various operators.
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