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

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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.

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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

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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.

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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

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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.

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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

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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.

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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

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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.

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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

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Linux mastery : acpi


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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acpi

acpi shows battery status, thermal information etc using /proc filesystem. You know the empty battery slots can be hidden, it comes with variety of options such as

  • –battery
  • –ac-adapter, ac adapter information
  • –cooling, cooling information
  • –show-empty , shows non operational devices
  • –everything,
  • –help , manual for the command

Sample usage

acpi --everything
acpi --cooling
acpi --battery

OS like Ubuntu may miss this command can be added using

sudo apt install acpi