Unix

The diff command compare files line by line and displays a list of changes between two file. You can use diff command to:

  1. See the changes between one version of a file.
  2. Compare two configuration or program files.
  3. Create a patch file which can be applied with the Linux / Unix program patch.

Say hello to colordiff

colordiff is a wrapper for diff and produces the same output as diff but with coloured syntax highlighting at the command line to improve readability. colordiff has been tested on various flavours of Linux and under OpenBSD, but should be broadly portable to other systems.

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Reading an IP address in a shell script requires many time and various Linux distributions stores IP address in different text files. So most of us end up writing shell pipes/scripts to get the information using ifconfig | grep 'inet addr:'| grep -v '127.0.0.1' | cut -d: -f2 | awk '{ print $1}' syntax. There is an alternative to ifconfig+shell pipe hack – ifdata command. It is a little know tool that can be used to check for the existence of a network interface and find out info about your interface such as IP, netmask, MTU and much more. No need to write shell pipes and fetch information via ifconfig or ip command. This command is designed to be easily used by a shell script.

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Most sysadmin will run low on disk space. Users will demand more space and you need to free space. You will find out files that’s a waste of space and delete it or move to an archive medium. But, how do you find the right files to delete that can help recover maximum space? Say hello to agedu tool (pronounced as ‘age dee you’) – it scans a directory tree and produces reports about how much disk space is used in each directory and subdirectory, and also how that usage of disk space corresponds to files with last-access times a long time ago. In other words, this command might help you to free up disk space.

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Do you need a simple open source cross-platform command line tool that converts web pages and HTML to a PDF file? Look no further, try wkhtmltopdf.

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Oneko is a little fun app. It will change your cursor into mouse and creates a little cute cat and the cat start chasing around your mouse cursor. The word “neko” means “cat” in Japanese and it was originally written by a Japanese author as a Macintosh desktop accessory.

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The remark command is a little know tool that can be used to color syslog file as well as output of of programs such as ping, traceroute, and much more.

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Most embedded Linux / BSD systems such as routers, servers and nas devices comes with console interface (serial port with RS-232). BIOS can uses this, and after boot BIOS screen I/O is redirected so that you can use the device. RS-232 is also used for communicating to headless server, where no monitor or keyboard is installed, during boot when operating system is not running yet and therefore no network connection is possible. You need to use a serial cable between your computer and embedded system or server. In this post I will cover five conman utilities used for serial communication under Linux / Unix / *BSD and Mac OS X.

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The pv command allows you to see the progress of data through a pipeline. It provides the following info:

  1. Time elapsed
  2. Percentage completed (with progress bar)
  3. Current throughput rate
  4. Total data transferred
  5. ETA

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You can display man pages in colors. Similarly, you can display info pages in colors. The info command is used under Linux or Unix to read multipage documentation and act as help viewer working on a command line interface, useful when there is no GUI available on the server. The info command processes info files. All info files are are in Texinfo format. You get the documentation tree. pinfo is a little known tool that can display info pages in colors.

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