Prologue

This is a collection of useful Linux commands that, you don’t need them often, but will go search for every time. So, just as a memo to save the time. 😏

This article will be updated from time to time as I use and explore Linux.

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Change password

passwd

Create sudo-enabled user

See Create sudo-Enabled User on Linux.

Quick Installation

Install Java

1	apt install openjdk-17-jdk openjdk-17-jre

Switch Java version

1	sudo update-alternatives --config java

Install Conda

Official page: Miniconda.

Replace bash with zsh or others if you are using other shells.

mkdir -p ~/miniconda3
wget https://repo.anaconda.com/miniconda/Miniconda3-latest-Linux-x86_64.sh -O ~/miniconda3/miniconda.sh
bash ~/miniconda3/miniconda.sh -b -u -p ~/miniconda3
rm -rf ~/miniconda3/miniconda.sh
~/miniconda3/bin/conda init bash

Utilities

Count all files under current directory

1	ls -1 \| wc -l

Count all files with certain extension

1	find . -type f -name "*.ext" \| wc -l

Count total line numbers of all files

1	find . -type f -name "*.ext" -print0 \| xargs -0 wc -l

Show file size

ls -lh

Create Link

Symbolic link

1	ln -s /path/to/file /path/to/link

Hard link

1	ln /path/to/file /path/to/link

Zip/Unzip

I like Zip.

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zip archivename.zip filename1 filename2 filename3
zip -r archivename.zip directory_name1 directory_name2 file1 file1
unzip filename.zip -d /path/to/directory

To untar a file.

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tar -xvf foo.tar
tar -xvzf foo.tar.gz
tar -xvjf foo.tar.bz2

Remote Connection

Perhaps this is for Windows.

Connect via SSH

1	ssh user@host

Some times the server may prompt password every time. In this case, you can send your public key to the server. First, generate key pair using ssh-keygen. This command exists on both Windows and Linux. It will generate id_rsa and id_rsa.pub under .ssh. The filename may vary.