The Linux Swiss army knife

Commands that will make you forget the GUI

Not long ago, I wrote a post with 25 one-command-liners that allow you to do complex things with just one line without using the graphical interface. Now, I will show you a list of commands to turn you into the perfect Linux mechanic.

Note: All commands have been tested on ubuntu 20.04. To execute some commands, you will need administrator permissions.

System information

Check the battery’s status via the terminal

This command outputs a lot of status and statistical information about the battery.

$ upower -i /org/freedesktop/UPower/devices/battery_BAT0

In my case, I’m using ubuntu on a virtualized machine, so it doesn’t show relevant stats, but if you try it on a native installation, it will show you a lot of helpful information.

Time the machine has been running

The command returns information about how long the system has been running since it was started up the last time.

$ uptime

Show File system structure

The command shows the description of the file system hierarchy.

$ man hier

Display disk usage information

This command shows the disk usage information.

$ df -k

Display information about the CPU

This command shows the CPU usage information.

$ lscpu

Display a calendar with the current day highlighted

This command displays a simple calendar.

$ cal

Display Bandwidth usage

I love this utility; it is handy to know what is happening on your computer and where it is connecting to.

$ apt-get install iftop
$ iftop

List network interfaces

This command shows the network interfaces with the “ethernet” name.

$ lspci | egrep -i 'network|ethernet'

Display information about your kernel release

$ uname -a

Display System Hardware information

This command display a lot of information about your Hardware.

$ sudo lshw

If you prefer the short version in HTML format:

$ sudo lshw -html > systemInfo.html

A trick, in the command console, you can display the result in the language of your choice with the following commands:

$ export LANG=en_US.UTF-8
$ export LANGUAGE=en

System admin

Reboot the system

$ sudo reboot

Shutdown the system at a specific time

$ sudo shutdown -h 19:05 "Some message..."

Start/Stop/Restart a service

$ sudo systemctl start serviceName
$ sudo systemctl stop serviceName
$ sudo systemctl restart serviceName

Checking a service status

$ sudo systemctl status serviceName

Enabling/Disabling a service to run at boot time

$ sudo systemctl enable serviceName
$ sudo systemctl disable serviceName

Increasing the size of the swapfile

The primary function of swap space is to substitute disk space for RAM when RAM fills up and more space is needed. With this command, you can set the size of the swap file.

1. Turn off all swap processes

$ sudo swapoff -a

2. Resize the swap to 4GB

$ sudo dd if=/dev/zero of=/swapfile bs=1G count=4

if: input file, of output file, bs: block size

3. Make the file usable as a swap

$ sudo mkswap /swapfile

4. Activate the swap file

$ sudo swapon /swapfile

Schedule jobs with Crontab Command

Cron is a regular background process manager (daemon) that runs processes at regular intervals (for example, every minute, day, week, or month). The processes to be run and the time they should run is specified in the crontab file.

1. List schedule jobs

$ crontab -l

//00 * * * * nameOfTheCommandToExecute

Cron job every hour.

2. Edit the crontab

$ crontab -e

Create a temporary aliase

An easy way to save time is to create an aliased for the most used commands.

#alias [name]="[command]"
$ alias dir="ls -la"

Media

Mute volume

$ amixer set Master muteclear

Find duplicate files based on the MD5 hash

$ find -type f -exec  md5sum '{}' ';' |  sort |  uniq --all-repeated=separate -w 33 |  cut -c 35-

Convert camelCase

With this command, you can convert the contents of a file to lowercase.

$ sed -e 's/\(.*\)/\L\1/' hello.txt > output.txt

Find files greater between X and Y

Find all files which are accessed N days back

$ find / -atime 2

Find modifies files in the last N minutes

$ find / -mmin -1

Various

With this utility, you can convert text to json format.

$ sudo apt-get install jshon
$ echo '{"name": "Kesk","surname":"norem"}' | jshon 

Extra

To finish, nothing better than a couple of games to play from the command line. Yes, you can play them from the command line.

Terminal games

Greed

$ sudo apt-get install greed
$ greed

Use the arrow keys to eat as many digits as possible in any direction.

Pacman

$ sudo apt-get install pacman4console
$ pacman4console

https://github.com/YoctoForBeaglebone/pacman4console

If you have arrived here, I invite you to look at these other 25 Awesome Linux Command One-Liners, where you will find combinations of Linux commands that I am sure will surprise you.

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