How to Check if a File or Directory Exists in Bash [+ Examples]

bash check if file exists

You can check whether a file or directory exists on a Linux system using the test command in bash. See our examples below to find out how. The test Command Syntax test EXPRESSION The test command will evaluate the EXPRESSION. Expressions can be built using the following operators and can be built using a combination of operators. -d file True if file is a Directory. [[ -d demofile ]] -e file True if file Exists. [[ -e demofile ]] -f file True if file is a regular File. [[ … Read more

Building a Python Script to Resize & Watermark Images [Code Included]

Building a Python Script to Resize Watermark Images

In this project, we take you through building, packaging, and publishing a command-line application using Python to resize and watermark images. Whenever I complete an article for LinuxScrew, I need to go through and add watermarks and make other small adjustments to any photos I’ve taken. This can be tedious so I thought, why not automate it. Then I thought, why not make a command-line app to do it (rather than just a bash script), and show you how you can make your own command-line … Read more

Guide to Foreign Key Constraints in MySQL and MariaDB [With Examples]

Guide to Foreign Key Constraints in MySQL

In this guide, we cover foreign key constraints in MySQL and MariaDB, along with a number of useful examples. MySQL (and its fork MariaDB) are Relational Database Management Systems (RDBMS) – Database Systems which hold data in tables which can be related to each other. Tables in an RDBMS are organized into columns that contain data in rows (also called tuples). Each row will usually have a Primary Key – a unique value to identify the row in the table. To define relationships between two rows in two different … Read more

Quickly and Easily Outlining Text in GIMP 2 [3 Easy Steps]

outline text in gimp 2

Here’s a quick 3-step method for outlining text in GIMP 2. GIMP is the most popular photo manipulation and image editing package for Linux. Many tutorials go through a long-winded process of converting the text to paths and expanding selections, but in the end, if you want quick results, this is the method to use. Step 1: Write some text using the text tool Click on the text tool in the toolbox, and write some text to outline. Step 2: Select the Text by Colour … Read more

Python “while” Loops [with Examples]

python while loops

This tutorial explains how to create loops in Python by using the “while” statement. Included below are the syntax and examples. In programming (and thus, in Python), a loop is a statement which will execute a block of code repeatedly until a condition is met, or the loop is broken out of manually. This article will look at Python Loops and conventions to use when writing them. Looping with the while statement, Syntax and Example Here is a basic loop which will increment (add 1) the variable ‘i’ … Read more

Python time.sleep() to Pause, Sleep, Wait or Stop a Python Script

Pause Sleep Wait or Stop a Python Script

There is a useful function in Python called ‘sleep()’. It’s part of the ‘time’ module and allows you to pause, sleep, wait, or stop a Python script or application. Python can be used to make useful command-line tools to streamline your workflow, but sometimes you need to wait for the user, or for a pre-defined amount of time. For example, you may want to prompt the user to press a key when they have finished reading instructions or give them time to override a default … Read more

Python List ‘sort()’ Method – Sorting Lists in Python Easily

Sorting Lists in Python Easily

In Python, there’s an easy way to sort lists: using the sort() method. This tutorial explains how to use sort(), with examples. We’ve covered the following in Python: Removing list items Checking if items are in lists Finding items in lists Now it’s time to find out how to sort a list. Syntax for the sort() Method list.sort(reverse=True|False, key=sortFunction) Note that: ‘reverse’ should be a True/False boolean value and is optional reverse=True will sort the list descending The default is reverse=False True/False values case sensitive in Python! … Read more

Python: Find in a List and Return Values [using ‘filter’]

Python Find in a List and Return Values

This tutorial explains how to find items within a list in Python and return the values, using “filter”. Previously we covered checking whether items exist in a list in Python, but that could only tell us whether they were present, or not (with a boolean return value containing the result). If you are searching a list for a specific value, you already know what the value of the matching items will be so the above method is sufficient. However, what if you are searching by a set of … Read more

PHP trim() Function [With Examples]

PHP trim Function

You’ll want to process and tidy your user input before you do anything with it when building PHP apps. trim() is one of the tools available to do this – it removes all white space from the beginning and end of a string. Whitespace is things like spaces, tabs, and newlines which may be invisible to the user. PHP trim Syntax trim ( $string [, $character_mask = ” \t\n\r\0\x0B” ] ) Note that: By default, $string will be returned by trim() with all whitespace removed from the beginning and end, including: … Read more

Categories PHP

Raspberry Pi Alternatives [2021] – 8 Best Single Board Computers

Raspberry Pi Alternatives

The rise and rise of the Raspberry Pi’s popularity – as a home server, media box, emulation machine, or maker platform – has led to a host of imitators, and in some cases, successors. Finding the right single-board computer for your project will make development easier- so here’s a summary of some of the single-board computers getting about in 2021. 8 Best Alternatives to the Raspberry Pi We’ll only include boards with built-in memory and video out – all in one single board computers and … Read more