command line tool – Sick Gaming

Posted on March 5, 2020 by — Leave a comment

Manage tasks and projects on Fedora with Taskwarrior

There are a multitude of applications to manage your todo list. One of these apps is Taskwarrior, it allows you to manage your task in the terminal without a GUI. This article will show you how to get started using it.

What is Taskwarrior?

Taskwarrior is CLI task manager and organizer. It is flexible, fast, and unobtrusive. It does its job then gets out of your way.

Taskwarrior uses $HOME/.taskrc and $HOME/.task to store your settings and tasks respectively.

Getting started with Taskwarrior

It’s easy to use the Taskwarrior to add your daily missions. These are some simple commands. To add tasks:

$ task add buy milk Created task 1. $ task add buy eggs Created task 2. $ task add bake cake Created task 3.

To list your tasks, you can use the task command on its own for the simplest listing:

$ task ID Age Description Urg 1 17s buy milk 0 2 14s buy eggs 0 3 11s bake cake 0 3 tasks.

To mark a task as complete, use the done keyword:

$ task 1 done Completed task 1 'buy milk'. Completed 1 task.
$ task 2 done Completed task 2 'buy eggs'. Completed 1 task.
$ task [task next] ID Age Description Urg 1 57s bake cake 0 1 task

Diving deeper into Taskwarrior

Priority management

Taskwarrior (task) is designed to help prioritize your tasks. To do this, task has multiple implicit and explicit variables it can use to determine an “Urgency” value.

Consider the following list.

$ task [task next] ID Age Description Urg 1 2min buy eggs 0 2 2min buy flour 0 3 2min bake cake 0 4 2min pay rent 0 5 3s install fedora 0 5 tasks

One could argue that paying your rent and installing Fedora have a higher priority than baking a cake. You can tell task about this by using the pri modifier.

$ task 4 mod pri:H Modifying task 4 'pay rent'. Modified 1 task.
$ task 5 mod pri:M Modifying task 5 'install fedora'. Modified 1 task.
$ task [task next] ID Age P Description Urg  4 4min H pay rent 6
 5 2min M install fedora 3.9 1 4min buy eggs 0 2 4min buy flour 0 3 4min bake cake 0 5 tasks

Rent is very important, it has a due date that we need to pay it by, such as within 3 days from the 1st of the month. You can tell task this by using the due modifier.

$ task 4 mod due:3rd Modifying task 4 'pay rent'. Modified 1 task.
$ task [task next] ID Age P Due Description Urg 4 12min H 2d pay rent 13.7 5 10min M install fedora 3.9 1 12min buy eggs 0 2 12min buy flour 0 3 12min bake cake 0 5 tasks
$ date Sat Feb 29 11:59:29 STD 2020

Because the 3rd of next month is nearby, the urgency value of rent has skyrocketed, and will continue to do so once we have reached and passed the due date.

However, not all tasks need to be done right away. Say for example you don’t want to worry about paying your rent until it is posted on the first of the month. You can tell taskwarrior about this using the wait modifier. (Hint: in the following example, som is short for “start of month,” one of the shortcuts taskwarrior understands.)

$ task 4 mod wait:som Modifying task 4 'pay rent'. Modified 1 task.
$ task [task next] ID Age P Description Urg 5 14min M install fedora 3.9 1 16min buy eggs 0 2 16min buy flour 0 3 16min bake cake 0 4 tasks

You will no longer be able to see the pay rent task until the start of the month. You can view waiting tasks by using task waiting:

$ task waiting ID Age P Wait Remaining Due Description 4 18min H 2020-03-01 11h 2020-03-03 pay rent 1 task

There are a few other modifiers you can define. Schedule and until will place a “start” date and remove a task after a date respectfully.

You may have tasks that require other tasks to be completed. To add a dependency for other tasks, use the dep modifier:

$ task [task next] ID Age P Description Urg 5 30min M install fedora 3.9 1 33min buy eggs 0 2 33min buy flour 0 3 33min bake cake 0 4 tasks
$ task 3 mod dep:1,2 Modifying task 3 'bake cake'. Modified 1 task. $ task [task next] ID Age Deps P Description Urg 1 33min buy eggs 8 2 33min buy flour 8 5 31min M install fedora 3.9 3 33min 1 2 bake cake -5 4 tasks

This will modify the priorities of any tasks that is blocking a task. Now buying eggs and flour is more urgent because it is preventing you from performing a task.

Annotations

You can add notes to a task using task <number> annotate:

$ task 3 anno No blueberries Annotating task 3 'bake cake'. Annotated 1 task. $ task [task next] ID Age Deps P Description Urg 1 1h buy eggs 8 2 1h buy flour 8 5 1h M install fedora 3.9 3 1h 1 2 bake cake -4.2 2020-02-29 No blueberries 4 tasks

Organizing tasks

Tasks can being assigned to projects and tags by using the project modifier and adding a tag using the + sign followed by the tag name, such as +problem.

Putting it all together

You can combine everything you learned to create a task in one line with all the required options.

$ task add Write Taskwarrior post \
pri:M due:1m wait:som until:due+2w sche:15th \
project:magazine +taskwarrior +community +linux Created task 6. The project 'magazine' has changed. Project 'magazine' is 0% complete (1 task remaining).
$ task 6 No command specified - assuming 'information'. Name Value ID 6 Description Write Taskwarrior post Status Waiting Project magazine Entered 2020-02-29 13:50:27 (6s) Waiting until 2020-03-01 00:00:00 Scheduled 2020-03-15 00:00:00 Due 2020-03-30 14:50:27 Until 2020-04-13 14:50:27 Last modified 2020-02-29 13:50:27 (6s) Tags taskwarrior community linux Virtual tags SCHEDULED TAGGED UDA UNBLOCKED UNTIL WAITING YEAR LATEST PROJECT PRIORITY UUID 27768737-f6a2-4515-af9d-4f58773c76a5 Urgency 5.3 Priority M

Installing Taskwarrior on Fedora

Taskwarrior is available in the default Fedora repository. To install it use this command with sudo:

$ sudo dnf install task

For rpm-ostree based distributions like Fedora Silverblue:

$ sudo rpm-ostree install task

Tips and tricks

Taskwarrior has a hook system, meaning that there are many tools you can plug in, such as bugwarrior!
Taskwarrior can connect to a taskserver for server/client setups. (This is left as an exercise for the reader for now.)

Photo by Bogdan Kupriets on Unsplash.

Posted on December 18, 2019 by — Leave a comment

Make sysadmin work on Fedora easier with screen

When you manage a Linux instance, you’ll find that your job is made much easier by the many tools designed specifically to deal with something specific within the system. For example, if you need to install packages, you have easy-to-use package managers that make that a breeze. If you need to create, resize or delete filesystems, you can do so using tools that are built to be used by humans. The same goes for managing services and browsing logs with systemd using the systemctl and journalctl commands respectively. The screen tool is another such example.

You can run all of those tools directly at the command line interface. But if you’re connecting to a server remotely using SSH, sometimes you need another layer between you and the operating system so the command you’re running doesn’t stop if your remote connection terminates. Sysadmins do this to prevent sudden termination in case of a connection issue, but also on purpose to run a command that needs to keep running indefinitely in the background. Enter the screen utility.

Introducing screen

The screen tool allows you to have multiple sessions (called screens) that are independent from each other and that you can name, leave and join as you desire. It’s multi-tasking for the remote CLI. You can get started with it simply by running this command:

$ screen

The command creates a screen and connect you to it: your current session is now a screen. You can run any command that does something and doesn’t automatically terminate after a few seconds. For example, you might call a web app executable or a game server. Then press Ctrl+A and, right after that, the D key and you will detach from the screen, leaving it running in the background.

The Ctrl+A combination, given that it is part of every screen command, is often shortened in documentation to C-a. Then the detach command used earlier can be described simply as C-a d.

Getting in and out of sessions

If you want to connect to that screen again, run screen -r and you will attach to that screen. Just running screen will create a new screen, and subsequent screen -r commands will print out something like this:

There are several suitable screens on: 5589.pts-0.hostname (Detached) 5536.pts-0.hostname (Detached) Type "screen [-d] -r [pid.]tty.host" to resume one of them.

You can then choose whether to resume the first or the second screen you created by running either one of these commands:

$ screen -r 5536
$ screen -r 5589

Adding the rest of the name of the string is optional in this case.

Named screens

If you know you’ll have multiple screens, you might want to be able to connect to a screen using a name you choose. This is easier than choosing from a list of numbers that only reflect the process IDs of the screen sessions. To do that, use the -S option as in the following example:

$ screen -S mywebapp

Then you can resume that screen in the future using this command:

$ screen -r mywebapp

Starting a process in the background using screen

An optional argument is the command to be executed inside the created session. For example:

$ screen -S session_name command args

This would be the same as running:

$ screen -S session_name

…And then running this command inside the screen session:

$ command args

The screen session will terminate when the command finishes its execution.

This is made particularly useful by passing the -dm option, which starts the screen in the background without attaching to it. For example, you can copy a very large file in the background by running this command:

$ screen -S copy -d -m cp /path/to/file /path/to/output

Other screen features

Now that you’ve seen the basics, let’s see some of the other most commonly used screen features.

Easily switching between windows in a screen

When inside a screen, you can create a new window using C-a c. After you do that, you can switch between the windows using C-a n to go to the next one and C-a p to go to the previous window. You can destroy (kill) the current window with C-a k.

Copying and pasting text

The screen tool also enables you to copy any text on the screen and paste it later wherever you can type some text.

The C-a [ keybinding frees your cursor of any constraints and lets it go anywhere your will takes it using the arrow keys on your keyboard. To select and copy text, move to the start of the string you want to copy, and press Enter on the keyboard. Then move the cursor to the end of the text you want to copy and press Enter again.

After you’ve done that, use C-a ] to paste that text in your shell. Or you can open a text editor like vim or nano and paste the text you copied there.

Important notes about screen

Here are some other tips to keep in mind when using this utility.

Privileged sessions vs. sudo inside a screen

What if you need to run a command with root privileges inside screen? You can run either of these commands:

$ screen -S sessionname sudo command
$ sudo screen -S sessionname command

Notice that the second command is like running this command:

# screen -S sessionname command

Seeing things this way makes it a lot more obvious coupled with the fact that each screen is associated to a user:

The first one creates a screen with root privileges that can be accessed by the current user even if, within that screen, they switch to another user or root using the sudo -i command.
The second one creates a screen that can only be accessed by the root user, or by running sudo screen -r as a user with the appropriate sudo access.

Notes about screen in systemd units

You might be tempted to run a screen session in the background as part of a systemd unit executed at startup, just like any Unix daemon. That way you can resume the screen session and interact with whatever you ran that way. That can work, but you need to consider that it requires the right setup.

By default, systemd assumes services are either oneshot, meaning they set up something and then shut down, or simple. A service is simple by default when you create a unit file with no Type. What you actually need to do is to set the Type to forking, which describes screen‘s actual behavior when the -dm option is passed. It starts the process and then forks itself, leaving the process running in the background while the foreground process closes.

If you don’t set that, that screen behavior is interpreted by systemd as the service exiting or failing. This causes systemd to kill the background process when the foreground process exits, which is not what you want.

Photo by Vlad Tchompalov on Unsplash.

Posted on August 19, 2019 by — Leave a comment

Command line quick tips: Searching with grep

If you use your Fedora system for more than just browsing the web, you have probably needed to search for text in your files. For instance, you might be a developer that can’t remember where you left some code snippet. Or you might be looking for a setting stored in your system configuration files. Whatever the reason, there are plenty of ways to search for text on your Fedora system. This article will show you how, including using the built-in utility grep.

Introducing grep

The grep utility allows you to search for text, or more specifically text patterns, on your file system. The name grep comes from global regular expression print. Yikes, what a mouthful! This is because a regular expression (or regex) is a way of defining text patterns.

The grep utility lets you find and print out matches on these patterns — thus the name. It’s a powerful system, and you can even find it in modern code editors like Visual Studio Code or Atom.

Regular expressions

Harnessing all the power of regular expressions is a topic bigger than this article, for sure. The simplest kind of regex can be just a word, or a portion of a word. That pattern is simply “the following characters, in the same order.” The pattern is searched line by line. For example:

pciutil – matches any time the 7 characters pciutil appear together — including pciutil, pciutils, pciutil123, and foopciutil.
^pciutil – matches any time the 7 characters pciutil appear together immediately at the beginning of a line (that’s what the ^ stands for)
pciutil$ – matches any time the 7 characters pciutil appear together immediately before the end of a line (that’s what the $ stands for)

More complicated expressions are also possible. Special characters are used in a regex as wildcards, or to change the way the regex works. If you want to match on one of these characters, use a \ (backslash) before the character.

For instance, the . (period or full stop) is a wildcard that matches any single character. If you use it in the expression pci.til, it matches pciutil, pci4til, or pci!til, but does not match pcitil. There must be a character to match the . in the regular expression.

The ? is a marker in a regex that marks the previous element as optional. So if you built on the previous example, the expression pci.?til would also match on pcitil because there need not be a character between i and t for a valid match.

The + and * are markers that stand for repetition. While + stands for one or more of the previous element, * stands for zero or more. So the regex pci.+til would match any of these: pciutil, pci4til, pci!til, pciuuuuuutil, pci423til. However, it wouldn’t match pcitil — but the regex pci.*til would.

Examples of grep

Now that you know a little about regex, let’s put it to work. Imagine that you’re trying to find a configuration file that mentions a user account jpublic. You tried a bunch of files already, but none were the correct one, and you’re sure it’s there. So, try searching the /etc folder (using sudo because some subfolders are not readable outside the root account):

$ sudo grep -r jpublic /etc/

The -r switch searches the folder recursively. The utility prints a list of matching files, and the line where the hit occurred. In most modern terminal environments, the hit is color highlighted for better readability.

Imagine you have a much larger selection of files in /home/shared and you need to establish which ones mention the name MacNulty. However, you’re not sure whether the capitalization will be consistent, and you’re just looking for names of files, not the context. Also, you believe someone may have misspelled the name as McNulty in some places.

Use the -l switch to only output filenames with a match, a ? marker for optional a in the name, and -i to make the search case-insensitive:

$ sudo grep -irl 'ma\?cnulty' /home/shared

This command will match on strings like Macnulty, McNulty, Mcnulty, and macNulty with no problem. You’ll get a simple list of filenames where the match was found in the contents.

These are only the simplest ways to use grep and regular expressions. You can learn a lot more about both using the info grep command.

But wait, there’s more…

The grep command is venerable but in some situations may not be as efficient as newer search utilities. For instance, the ripgrep utility is engineered to be a fast search utility that can take the place of grep. We covered ripgrep as part of an article on Rust and Rust applications previously in the Magazine:

Oxidizing Fedora: Try Rust and its applications today

It’s important to note that ripgrep has its own command line switches and syntax. For example, it has simple switches to print only filename matches, invert searches, and many other useful functions. It can also ignore based on .rgignore files placed in any subdirectories. (It’s also noteworthy that the -r switch is used differently for ripgrep, because it is automatically recursive.)

To install, use this command:

$ sudo dnf install ripgrep

To explore the options, use the manual page (man rg). You’ll find that many, but not all, options are the same as grep.

Have fun searching!

Posted on August 9, 2019 by — Leave a comment

Use a drop-down terminal for fast commands in Fedora

A drop-down terminal lets you tap a key and quickly enter any command on your desktop. Often it creates a terminal in a smooth way, sometimes with effects. This article demonstrates how it helps to improve and speed up daily tasks, using drop-down terminals like Yakuake, Tilda, Guake and a GNOME extension.

Yakuake

Yakuake is a drop-down terminal emulator based on KDE Konsole techonology. It is distributed under the terms of the GNU GPL Version 2. It includes features such as:

Smoothly rolls down from the top of your screen
Tabbed interface
Configurable dimensions and animation speed
Skinnable
Sophisticated D-Bus interface

To install Yakuake, use the following command:

$ sudo dnf install -y yakuake

Startup and configuration

If you’re runnign KDE, open the System Settings and go to Startup and Shutdown. Add yakuake to the list of programs under Autostart, like this:

It’s easy to configure Yakuake while running the app. To begin, launch the program at the command line:

$ yakuake &

The following welcome dialog appears. You can set a new keyboard shortcut if the standard one conflicts with another keystroke you already use:

Now click the menu button, and the following help menu appears. Next, select Configure Yakuake… to access the configuration options.

You can customize the options for appearance, such as opacity; behavior, such as focusing terminals when the mouse pointer is moved over them; and window, such as size and animation. In the window options you’ll find one of the most useful options is you use two or more monitors: Open on screen: At mouse location.

Using Yakuake

The main shortcuts are:

F12 = Open/Retract Yakuake
Ctrl+F11 = Full Screen Mode
Ctrl+) = Split Top/Bottom
Ctrl+( = Split Left/Right
Ctrl+Shift+T = New Session
Shift+Right = Next Session
Shift+Left = Previous Session
Ctrl+Alt+S = Rename Session

Below is an example of Yakuake being used to split the session like a terminal multiplexer. Using this feature, you can run several shells in one session.

Tilda

Tilda is a drop-down terminal that compares with other popular terminal emulators such as GNOME Terminal, KDE’s Konsole, xterm, and many others.

It features a highly configurable interface. You can even change options such as the terminal size and animation speed. Tilda also lets you enable hotkeys you can bind to commands and operations.

To install Tilda, run this command:

$ sudo dnf install -y tilda

Startup and configuration

Most users prefer to have a drop-down terminal available behind the scenes when they login. To set this option, first go to the app launcher in your desktop, search for Tilda, and open it.

Next, open up the Tilda Config window. Select Start Tilda hidden, which means it will not display a terminal immediately when started.

Next, you’ll set your desktop to start Tilda automatically. If you’re using KDE, go to System Settings > Startup and Shutdown > Autostart and use Add a Program.

If you’re using GNOME, you can run this command in a terminal:

$ ln -s /usr/share/applications/tilda.desktop ~/.config/autostart/

When you run for the first time, a wizard shows up to set your preferences. If you need to change something, right click and go to Preferences in the menu.

You can also create multiple configuration files, and bind other keys to open new terminals at different places on the screen. To do that, run this command:

$ tilda -C

Every time you use the above command, Tilda creates a new config file located in the ~/.config/tilda/ folder called config_0, config_1, and so on. You can then map a key combination to open a new Tilda terminal with a specific set of options.

Using Tilda

The main shortcuts are:

F1 = Pull Down Terminal Tilda (Note: If you have more than one config file, the shortcuts are the same, with a diferent open/retract shortcut like F1, F2, F3, and so on)
F11 = Full Screen Mode
F12 = Toggle Transparency
Ctrl+Shift+T = Add Tab
Ctrl+Page Up = Go to Next Tab
Ctrl+Page Down = Go to Previous Tab

GNOME Extension

The Drop-down Terminal GNOME Extension lets you use this useful tool in your GNOME Shell. It is easy to install and configure, and gives you fast access to a terminal session.

Installation

Open a browser and go to the site for this GNOME extension. Enable the extension setting to On, as shown here:

Then select Install to install the extension on your system.

Once you do this, there’s no reason to set any autostart options. The extension will automatically run whenever you login to GNOME!

Configuration

After install, the Drop Down Terminal configuration window opens to set your preferences. For example, you can set the size of the terminal, animation, transparency, and scrollbar use.

If you need change some preferences in the future, run the gnome-shell-extension-prefs command and choose Drop Down Terminal.

Using the extension

The shortcuts are simple:

` (usually the key above Tab) = Open/Retract Terminal
F12 (customize as you prefer) = Open/Retract Terminal

Posted on August 13, 2018 by — Leave a comment

Convert file systems with Fstransform

Few people know that they can convert their filesystems from one type to another without losing data, i.e. non-destructively. It may sound like magic, but Fstransform can convert an ext2, ext3, ext4, jfs, reiserfs or xfs partition to another type from the list in almost any combination. More importantly, it does so in-place, without formatting or copying data anywhere. Atop of all this goodness, there is a little bonus: Fstransform can also handle ntfs, btrfs, fat and exfat partitions as well.

Before you run it

There are certain caveats and limitations in Fstransform, so it is strongly advised to back up before attempting a conversion. Additionally, there are some limitations to be aware of when using Fstransform:

Both the source and target filesystems must be supported by your Linux kernel. Sounds like an obvious thing and exposes zero risk in case you want to use ext2, ext3, ext4, reiserfs, jfs and xfs partitions. Fedora supports all of that just fine.
Upgrading ext2 to ext3 or ext4 does not require Fstransform. Use the Tune2fs utility instead.
The device with source file system must have at least 5% of free space.
You need to be able to unmount the source filesystem before you begin.
The more data your source file system stores, the longer the conversion will last. The actual speed depends on your device, but expect it to be around one gigabyte per minute. The large amount of hard links can also slow down the conversion.
Although Fstransform is proved to be stable, please back up data on your source filesystem.

Installation instructions

Fstransform is already a part of Fedora. Install with the command:

sudo dnf install fstransform

Time to convert something

Converting one file system to another in-place can take a while

The syntax of the fstransform command is very simple: fstransform <source device> <target file system>. Keep in mind that it needs root privileges to run, so don’t forget to add sudo in the beginning. Here goes an example:

sudo fstransform /dev/sdb1 ext4

Note that it is not possible to convert a root file system, which is a security measure. Use a test partition or an experimental thumb drive instead. In the meantime, Fstransform will through a lot of auxiliary output in the console. The most useful part is the estimated time of completion, which keep you informed about how long the process will take. Again, few small files on an almost empty drive will make Fstransform do its job in a minute or so, whereas more real-world tasks may involve hours of wait time.

More file systems are supported

As mentioned above, it is possible to try Fstransform with ntfs, btrfs, fat and exfat partitions. These types are very experimental, and nobody can guarantee that the converion will flow perfect. Still, there are many success stories, and you can add your own by testing Fstransform with a sample data set on a test partition. Those additional file systems can be enabled by the use of the –force-untested-file-systems parameter:

sudo fstransform /dev/sdb1 ntfs --force-untested-file-systems

Sometimes the process may iterrupt with an error. Feel free to repeat the command again — it may eventually complete the conversion from second or third attempt.