Linux : command output to a file


In this series of mini posts I will teach you a Linux lesson every day, it can be command , tricks , how to. The post will cover for beginner to advanced level. Welcome to Linux terminal.

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how to output a command result to a file?

In Linux we can output command result directly to a file using output operator(>). Suppose we want to list directory and redirect to to it a file called mydir, here is the trick

ls > mydir
cat mydir

You may love to learn following Linux commands and tutorials

Linux cat


In this series of mini posts I will teach you a Linux lesson every day, it can be command , tricks , how to. The post will cover for beginner to advanced level. Welcome to Linux terminal.

Follow us and start learning Linux today

cat

cat is used to create ,view files in Linux. It is useful when dealing with scripts and output some command result. It can used to view multiple files as follows

cat file1 file2

To create file we can use the cat with an input file name as follows

cat> file name
Ctrl+Z

You may love to learn following Linux commands and tutorials

For copying content of a file into another we can use

cat myfile>file4
Ctrl+Z

Linux : arbitrary calculator language


In this series of mini posts I will teach you a Linux lesson every day, it can be command , tricks , how to. The post will cover for beginner to advanced level. Welcome to Linux terminal.

Follow us and start learning Linux today

bc

bc is a command line arithmetic calculator. It is a an arbitrary calculator language which means that it is an interactive calculator programming language. We can use expressions,variable,print,decision make statement etc

a=13
print a
a<1
0
a>12
1

A comparison with >,< return 0 if it fails or 1 if it it true, I think that make sense.

We can also use the bc with output statement as follows

echo '100*9'|bc

You may love to learn following Linux commands and tutorials

Linux ASCII character art with banner


In this series of mini posts I will teach you a Linux lesson every day, it can be command , tricks , how to. The post will cover for beginner to advanced level. Welcome to Linux terminal.

Follow us and start learning Linux today

banner

banner is a command for fun, it print first 10 character in a string with big ASCII character. Yo can install the banner using the following command

sudo get install sysvbanner
banner LINUX

You may love to learn these Linux commands and tutorials

Searching for a Linux command


In this series of mini posts I will teach you a Linux lesson every day, it can be command , tricks , how to. The post will cover for beginner to advanced level. Welcome to Linux terminal.

Follow us and start learning Linux today

apropos

Sometimes it is hard to remember everything we learned,earned. isn’t it ?. Linux has many commands, lots of commands, how can I memorize all these ? impossible.

Here is command every Linux had which help us to find commands based on purpose/keyword.

It can’t memorize but can help find something worthy

apropos search man page and bring a list of commands. For example apropos cpp will brings all cpp commands.

apropos python
apropos printer -- list all printer commands

You may love to learn these Linux commands and tutorials

Command line music player for Linux


In this series of mini posts I will teach you a Linux lesson every day, it can be command , tricks , how to. The post will cover for beginner to advanced level. Welcome to Linux terminal.

Follow us and start learning Linux today

aplay and aplaymidi

aplay allows us to play music from a terminal window with options such as delaying setting frequencies etc . Check out aplay –help for complete list of supported formats.

We can set duration of the play using the –duration option. It can play on a selected device on a network. It works with ALSA audio driver.

Wanna play a MIDI file ? aplaymidi command will be at your service. A hardware MIDI device is required to play the MIDI file

Sample usage

The following command will play the mp3 form 30 seconds

alpay -d 30 -r2500hz jinglebell.mp3
aplay --help
alpaymidi -d 30  play.midi

You may love to learn these Linux commands and tutorials

How to add web/desktop support for existing flutter app in Ubuntu


Have flutter project in hand which is built for Android and iOS, now want to built desktop and web counter part?

Make sure that you have enabled, web, desk features. To ensure this run the following

Flutter devices

If not please go through the web/desk support post.

How to enable Flutter Web support in Ubuntu Linux - How to enable Flutter Web development in Ubuntu Linux
How to enable Flutter Desktop support in Ubuntu Linux - How to setup Flutter Desktop development environment on Ubuntu

Here is the solution

Make sure you had an active internet connection.

Cd to your project folder and in the console enter these commands

For few second it will add tools for desktop and web features.

Flutter create . 

Run the flutter command

Flutter run -d chrome

Flutter will goes through building process and will bring you a local host id.

For desk top try to run

Flutter run -d windows/linux/mac 

How to enable Flutter Web support in Ubuntu Linux


Flutter can be used to create web applications, which is possible by enabling the feature. Before that I would like recommend the basic flutter setup on Ubuntu post.

How to install Flutter on Ubuntu Linux

Lets Install Flutter for Ubuntu Linux development. As a open source project, we can install the flutter SDK from GitHub.

The prerequisites

In order to clone the repository we have to use git . In case your SUSE doesn’t know what it is, let’s install it with snap . Also recommend to have Visual Code /Atom for editing the code.

The following post may help you to install VS Code on Ubuntu

Install the git

sudo snap install git

Clone the repo

Get the latest stable version from GitHub repository or alternatively can download from flutter site

git clone https://github.com/flutter/flutter.git -b stable --depth 1

Use the -b option to clone the stable version

Setup the path variable

You also need to set the path variable using the shell command as follows.

export PATH="$PATH:pwd/flutter/bin"

Call the Doctor

run Flutter doctor command to inspect status of your Flutter SDK

Flutter Doctor

Android IOS development

For Android you have to install the Android Studio for development tool support which can be download from official website.

For official documentation visit flutter.dev

Enable web feature

Before starting make sure you have chrome/chromium installed on your system. Otherwise the feature may not work

For enabling the web feature we have to switch to the beta channel ( web feature is an experimental feature and official full support is not yet released)

flutter channel beta
flutter upgrade
flutter config --enable-web

Run the flutter device command again and then check the web feature is list or not by using

flutter devices

and it will list the web feature

Test Run

Create sample Flutter project

flutter create myweb_app
Flutter Web on Ubuntu

run the app using flutter run command

flutter run -d chrome

For building the web we can use

flutter build web

How to enable Flutter Desktop support in Ubuntu Linux


Flutter can be used to create Linux applications, which is possible by enabling the feature. Before that I would like recommend the basic flutter setup on Ubuntu post.

How to install Flutter on Ubuntu Linux

Lets Install Flutter for Ubuntu Linux development. As a open source project, we can install the flutter SDK from GitHub.

The prerequisites

In order to clone the repository we have to use git . In case your SUSE doesn’t know what it is, let’s install it with snap . Also recommend to have Visual Code /Atom for editing the code.

The following post may help you to install VS Code on Ubuntu

Install the git

sudo snap install git

Clone the repo

Get the latest stable version from GitHub repository or alternatively can download from flutter site

git clone https://github.com/flutter/flutter.git -b stable --depth 1

Use the -b option to clone the stable version

Setup the path variable

You also need to set the path variable using the shell command as follows.

export PATH="$PATH:pwd/flutter/bin"

Call the Doctor

run Flutter doctor command to inspect status of your Flutter SDK

Flutter Doctor

Android IOS development

For Android you have to install the Android Studio for development tool support which can be download from official website.

For official documentation visit flutter.dev

Enable desktop feature

In order to make Linux ready for Flutter desktop development environment we should have following dependencies

  • clang
  • cmake
  • ninja- build
  • pkg-config
  • libgtk-3-dev
  • libblkid-dev
  • liblzma-dev

install them using snap/ apt-get command

sudo apt-get install clang cmake ninja-build pkg-config libgtk-3-dev libblkid-dev liblzma-dev

Now switch to the dev channel and run upgrade command, which will install necessary libraries and packages.

flutter channel dev
flutter upgrade

Configure the feature using config

flutter config --enable-linux-desktop

run the flutter doctor and then flutter devices as follows

flutter doctor
flutter devices

Make sure the devices command list the Linux desktop

Test Run

Create sample Flutter project

flutter create myweb_app

run the app using flutter run command

Flutter Desktop app in openSUSE

flutter run -d linux
or
flutter run

Happy fluttering