My book Create Simple GUI Applications with Python & Qt5 has been updated! New chapters on multithreading and packaging your apps.

Customize directory colors

You can use the command ls --color (or an alias) to show directories with colours for folders, files, links, etc. However, you may not realise these colours can be easily configured using bashrc and a configuration file.

Control memcached from the command line

memcached is a general-purpose distributed memory caching system originally developed by Danga Interactive for LiveJournal but now used by many other sites. It is often used to speed up dynamic database-driven websites by caching data and objects in RAM to reduce the number of times an external data source (such as a database or API) must be read. Here we describe the options available from the command line to control a memcached instance via unix socket or IP:port.

Collaborate in the shell with screen (multiuser)

Screen is a neat little program that allows you to use multiple virtual terminals in a single session on Unix/Linux and Mac. However, it does more than just that. It can also allow you to share your current session on a machine with another user - allowing you to collaboratively hack away at a problem in real time.

Bash Command Substitution

Bash command substitution performs a given command replacing the marker with the resulting standard output. It is particularly useful when you want to store the output of a command in a variable or as an alternative method of chaining multiple commands together.

Remove duplicate lines from text files (with sort)

A quick method to remove duplicates from text files - including for example CSV files - where multiple records have been added (perhaps automatically) at different times resulting in multiple copies of the same record scattered throughout the file. Here is a simple one-liner bash command to remove duplicates using sort.

Control Console with SysReq

System request (often abbreviated SysRq or Sys Req) is a key on keyboards for PCs that has no standard use. This key can be traced back to the operator interrupt key of the IBM System/370 mainframe computer. But under Linux there's a bunch of useful things available via this key.

Set CDPATH to ease folder navigation

CDPATH is an environment variable which tells the cd command where to look for the specified folder. By including the parent folders of commonly used locations you can access folders more easily - and without typing an entire path.

Use ifconfig.me to return your IP and Host

ifconfig.me is a web service that displays information about your connection, including IP address, hostname and User Agent string. Helpfully it provides a simplified interface that can be easily queried to get this information from the command line.

Use screen to manage persistent sessions

GNU Screen is a command-line application that allows use of multiple virtual sessions within a single real terminal or remote session. Importantly, it allows for persistent running of command-line applications independent of the shell that initiated them program, meaning active applications can persist during disconnection.