find

A large collection of Unix/Linux ‘find’ command examples

Linux/Unix FAQ: Can you share some Linux find command examples?

Sure. The Unix/Linux find command is very powerful. It can search the entire filesystem to find files and directories according to the search criteria you specify. Besides using the find command to locate files, you can also execute other Linux commands (grep, mv, rm, etc.) on the files and directories you find, which makes find extremely powerful. 

How to use higher-order functions with Option (instead of match expressions)

I originally wrote a long introduction to this article, but I decided to keep that introduction for the second article in this series. For this article I’ll just say:

  • idiomatic Scala code involves never using null values
  • because you never use nulls, it’s important to become an expert at using Option, Some, and None
  • initially you may want to use match expressions to handle Option values
  • as you become more proficient with Scala and Options, you’ll find that match expressions tend to be verbose
  • becoming proficient with higher-order functions (HOFs) like map, filter, fold, and many others are the cure for that verbosity

Given that background, the purpose of this article is to show how to use HOFs with Option values rather than match expressions.

A large collection of Unix/Linux ‘grep’ command examples

Linux grep commands FAQ: Can you share some Linux/Unix grep command examples?

Sure. The name grep means "general regular expression parser", but you can think of the grep command as a "search" command for Unix and Linux systems: it's used to search for text strings and more-complicated "regular expressions" within one or more files.

I think it's easiest to learn how to use the grep command by showing examples, so let's dive right in.

Scala Vector informational and mathematical methods (syntax, examples)

This page contains a collection of examples of how to use Scala Vector class informational and mathematical methods. Note that these same methods will also work with a Scala Seq, including IndexedSeq.

Informational and mathematical methods

As the name implies, these methods let you get information about the contents of a Vector, or perform mathematical expressions on a Vector.

Scala Vector filtering methods (examples)

This page contains a collection of examples of filtering methods that can be used with a Scala Vector class. I’ll first show a table that describes the filtering methods, and then show examples of them.

Unix find command: How to move a group of files into the current directory alvin May 16, 2018 - 9:51pm

I just bought a bunch of MP3 music files from Amazon, and when I downloaded the zip file they provide onto my Mac, it was a bunch of files in a bunch of subdirectories; not really convenient to work with when you’re trying to import them into iTunes. So I used this Unix find command to move all of the music files from the subdirectories they were scattered in into the root directory that was created when I expanded the zip file:

cd Amazon-Music-Folder
find . -type f -exec mv {} . \;

If you ever need to either copy or move a bunch of files with a single command, I hope this example shows the correct find command syntax for your needs. (If you need to copy the files, use the cp command instead of the mv command.)

Linux: Recursive file searching with grep -r (like grep + find)

Linux grep FAQ: How can I perform a recursive search with the grep command in Linux?

Solution: find + grep

For years I always used variations of the following Linux find and grep commands to recursively search subdirectories for files that match a grep pattern:

find . -type f -exec grep -l 'alvin' {} \;

This command can be read as, “Search all files in all subdirectories of the current directory for the string ‘alvin’, and print the filenames that contain this pattern.” It’s an extremely powerful approach for recursively searching files in all subdirectories that match the pattern I specify.

A Linux shell script (and commands) to find large files alvin July 14, 2017 - 11:14am

I made a mistake in configuring logrotate on a new Linux system, and almost ran into a problem because of that. Fortunately I saw the problem before it became a BIG problem, but as a result, I decided to add a script to my Linux system to check for large files, typically log files that have grown out of control for one reason or another.

Here then is a simple Linux shell script I named LargeFileCheck.sh, which searches the filesystem for files that are larger than 1GB in size: