Ben Chuanlong Du's Blog

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Special Characters to Avoid in Strings

This articles talks about special characters to avoid in various places. You might not encounter issues most of the time when violating rules stated below, however, you never know when things will break. It is more for a good-practice suggestion.

String for Shell

  1. When you pass parameters from one program …

Useful Plugins for Eclipse

Terminal Plug-in

"Terminal Plug-in" is a fully-working command-line terminal for Eclipse.

EasyShell

"EasyShell" allows to open a shell window or file manager from the popup menu in the navigation tree or editor view.

Vrapper

Vrapper provides Vim-like scheme for Eclispe. You can edit code similar as what you do in …

Advanced Use of "head" and "tail"

It is suggested that you use Python instead of Shell to manipulate text files!!

Besides passing an unsigned integer as parameter to the option -n, you can also pass a signed integer to it. When a signed integer is passed to -n, it means from/to (inclusive/exclusive similar to …

Advanced Use of "ls" in Linux

List Files Sorted by Time

You can list files sorted by time (newest first) using the -t option. Notice that the -t option is also support by hdfs dfs -ls.

ls -lht

Ignore Files

  1. You have to either enclose the pattern in quotes or escape the wildcard in patterns.

  2. Equivalent …

Sample Lines from a File Using Command Line

NOTE: the article talks about sampling "lines" rather than "records". If a records can occupy multiple lines, e.g., if any field contains a new line (\n), the following tutorial does not work and you have to fall back to more powerful tools such as Python or R.

Let's say …