When we need to use swap partition in Linux?

Recently i have an issue on my LightSail small instance which have 512MB of RAM,

I can not run react-script build on it

npm run build

Because of the issue: https://github.com/kitze/custom-react-scripts/blob/master/packages/react-scripts/template/README.md#npm-run-build-exits-too-early

So create a Linux swap is life saver.

Firstly, check if swap available :

sudo swapon --show

if it show nothing, then you don't have any swap yet.

Now, create a swap file, it should be 2x or 4x of your RAM capacity

sudo fallocate -l 1G /swapfile

To verify the swap is created

ls -lh /swapfile

To enable swap, you may need to change the permission

sudo chmod 600 /swapfile

make swap file

          sudo mkswap /swapfile        

then

sudo swapon /swapfile

check if it is ready

sudo swapon --show

 To enable swap permanent

Backup file

sudo cp /etc/fstab /etc/fstab.bak

Add the line at the end of file

/swapfile swap swap defaults 0 0

MacOS basic commands

1. Copy a folder into another folder

cp -r /path/folder/a /path/folder/b

result:

/path/folder/b
/path/folder/b/a

2. Move a folder into another folder

mv /path/folder/a /path/folder/b

result:

/path/folder/b
/path/folder/b/a

3. Remove files

rm -rf /path/to/file
rm -rf /path/to/file*

4. Process and ports

lsof -iTCP -sTCP:LISTEN -n -P
lsof -iTCP -sTCP:LISTEN -n -P | grep {PORT}

5. Kill a process

kill -9 ${PID}

6. Change owner of a folder

# for current user
sudo chown -R `id -un` /path/to/folder
# a user
sudo chown -R ${username} /path/to/folder