git init
ls -Force(ls -a)
git status
New-item(touch) file.txt -Type file
git status
git add .(\filename)
git status
git commit -m '[My name] What I have done'
git status
git log

vim file.txt
git status

git diff

git add .
git commit -m ' '

git log

git checkout .(filename,wildcard )##撤销,回到上一次提交

git log# see hash code

git checkout hashcode# jump to certain commit

vim file

git add .
git checkout -b another_branch

git commit -m ' '
git log

git checkout branch_name

git merge another_branch# at master branch

git status# find conflict
vim file## <<<<HEAD(Change in current branch)
#changes
#===
#changes
#>>>>another_branch(Changes to be merged)
# Modify the confilct manually
git add .
git commit -m ' '

git log

git clone 
git remote -v
## make some change 
git status
git push -u origin master
git status

pwd #show current path
cd /
cd ..
cd .
ls 
ls -a

sudo apt updaate
sudo apt list --upgradable
sudo apt upgrade

sudo apt search vlc
sudo apt install vlc
sudo apt remove vlc
sudo apt autoremove

pwd
ls
cd Doc	
touch testfile
mkdir testdir
cp testfile testdir#copy
cp testfile testdir/testfile2
cp testfile /home/specificpath
cp testfile ../testfile5#current path
rm restfile
rm -r testdir
rm *
vim testfile.txt


man ls#list manual
ls --help

find Documents
ls | grep Doc

ls >> output.txt
cat output.txt

echo "hello world"
echo "hello world" | >> output.txt
tail output.txt
head output.txt

echo $USER

alias showuser='echo $USER'
showuser
export linuxcourse='for beginners'
echo $linuxcourse
ls -a
vim .bashrc
# Then you can set the variable pernamently
# This is the way to set environment variables

pwd 
ls -a
ls -l
mkdir dir1
mkdir dir2
cd dir1
pwd
cd ..
cd /
ls
cd 
cd ~
clear

touch file1.txt
cp file dir
rm file
rm -r dir

which mongod#find the location
history

clear

sudo
ifconfig
iwconfig
ping google.com

uname -a

blkid

top

df
ls USB

sudo apt-get install...

#!/bin/bash 
#tell the interpreter

export PATH="$PWD:$PATH"

ln -s $PWD/topc /usr/local/bin/#y

declare
cat
cut 
sort
uniq
sed+正则表达式
ctrl R
grep
awk