Testing regular expressions

I’ve been working with regular expressions recently (a series of characters that define a search pattern) and wanted to share a useful testing tool I found.

https://regex101.com/ allows users to easily test expressions on sample strings and provides a useful explanation of the match conditions and information on any errors encountered.

If you’re new to Regex, give it a try.

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How to create symbolic links

Occasionally you will need to make a link to a file or directory in Linux. To create a symbolic link you will need to use the ln command, which will follow the form of;

ln -s <target> <link name>

Example: Assume you frequently use gnome-calculator and decide you want a link on your desktop so you can quickly start that application in the future. To accomplish this with a symbolic link you could do the following;

ln -s /usr/bin/gnome-calculator ~/Desktop/calculator

You can also update an old symbolic link by overwriting the link using the following command.

ln -sf /usr/bin/gnome-calculator ~/Desktop/calculator

or when linking to directories you will need to include an n option

ln -sfn /mydir/ linkname

Help in vi

Vi is a great text editor but requires practice to learn its many commands. To aid this process vi provides a great command called help. User’s can access an overview of the help command, by typing the following;

:help

For a listing of common commands used by vi, type;

:help quickref

For help with a specific command you can also type :help <command>. For example, to see the help for the insert command you would type;

:help i