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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. 

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.

How to use ‘awk’ to print columns from a text file (in any order)

One of my favorite ways to use the Unix awk command is to print columns of information from text files, including printing columns in a different order than they are in in the text file. Here are some examples of how awk works in this use case.

sed on macOS: How to append multiple lines of text to an HTML or XML file alvin December 19, 2017 - 3:40pm

As a brief note about the Linux/Unix sed command, today I learned how to append multiple lines of text to an HTML (or XML) file on macOS. The short answer is that I created a sed commands file named changes.sed with these contents:

The beginning of a Scala “FileUtils” class

In production code I recommend that you use a good “Files” library like Apache Commons IO, but if you want to create your own Scala FileUtils class, here’s some source code that can help you get started.

First, here’s some code for the FileUtils class (an object, technically):

How to process every line in a file with a Unix/Linux shell script

Unix/Linux shell script FAQ: How do I write a Unix or Linux shell script where I "do something" for every line in a text file?

Solution: An easy way to process every line in a text file is to use a Unix/Linux while loop in combination with the Linux cat command, like this:

Sorting ‘ls’ command output by filesize

I just noticed that some of the MySQL files on this website had grown very large, so I wanted to be able to list all of the files in the MySQL data directory and sort them by filesize, with the largest files shown at the end of the listing. This ls command did the trick, resulting in the output shown in the image:

ls -Slhr

The -S option is the key, telling the ls command to sort the file listing by size. The -h option tells ls to make the output human readable, and -r tells it to reverse the output, so in this case the largest files are shown at the end of the output.