ALPINE COMMANDS

Post by **admin** » Mon Jul 24, 2023 2:14 pm

In previous topics i already discussed about Alpine Linux. Still a brief about alpine linux is smallest linux with full docker support.
Listing here few usefull commands for Alpine Linux.

1. Assign Static Ip Address:

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auto eth0
iface eth0 inet static
        address 192.168.0.25
        subnet 255.255.255.0
        gateway 192.168.0.1

2. If you have installed Alpine in virtual machine sometime harddisk size needs to be incresed. Accordingly partition table needs to be modified.

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# after the virtual disk has already been expanded.
   apk add --no-cache cfdisk e2fsprogs-extra
# choose partition then "Resize" > "Write" (to finalize)
   cfdisk
# replace * with partition you are resizing
   resize2fs /dev/*

3. In virtuslbox disk size increases when application is installed or copied, but it remain extended evenif uninstalled/delete. To shrink the space one has to fill zero at free space. In Ubuntu a popular tool is used called zerofree. Though zerofree can be installed in Alpine, but as the disk is already mounted you cannot apply zero free. There is a way to zero fill free spaces in Alpine Linux.The code is:

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$ cat /dev/zero > zero.file
cat: write error: No space left on device
$ sync
$ rm zero.file 
$ sync

After this we need to shrink the vbox hard disk from command prompt. Code is:

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vboxmanage modifymedium --compact /path/to/thedisk.vdi

4. Sometime it is required to copy data from host machine to virtual machine running Alpine. A folder to be attached in virtualbox. Inside Alpine code is:

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mkdir -p /mnt/shared
apk add virtualbox-guest-additions linux-virt
reboot

Then mount the above folder

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modprobe -a vboxsf 
mount -t vboxsf  vbox_shared /mnt/shared

vbox_shared is the 'Folder Name' you decided in the virtualbox gui

5. Sometime host machine dont have internet. To install docker one can pull in a machine with internet and export this image with docker save command. Then compress it and load it with host having no internet with docker load command. The code is:
In machine with internet:

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apk add gzip
docker pull couchbase
docker save couchbase > couchbase.tar
ls -lh couchbase.tar
gzip -9 couchbase.tar
ls -lh couchbase.tar.gz

In host machine without internet:

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docker load < couchbase.tar.gz

6. Sometime jupyter notebook is made to run inside docker with port: 8888 forwarded. Still when notebook is started it shows on localhost. In order to access it from outside, you need to bind it with 0.0.0.0. The code is:

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jupyter-notebook --allow-root --ip 0.0.0.0 --port 8888

7. Docker create interactive container with port forward:

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docker create -t -i   -p:3000:3000 --name myubuntu ubuntu:latest

8. Docker start:

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docker start myubuntu

9. Docker access bash:

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docker exec -it myubuntu /bin/bash

10. See all open ports:

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netstat -lnptu

11. See a application loaction:

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which <application_name>