delete

Stop and remove all Docker containers

December 11, 2021

How to stop and remove all Docker containers.

Stop all containers

$ docker kill $(docker ps -q)

Remove all containers

$ docker rm $(docker ps -a -q)

Delete all docker images

$ docker rmi $(docker images -q)

Delete lines using sed

December 1, 2021

How to delete a line containing a pattern using sed.

Contents of test.txt.

$ cat test.txt
one
two
three

Delete a line matching the string “one.”

sed -i '/one/d' test.txt

Display test.txt

$ cat test.txt
two
three

Remove Oracle Java

November 30, 2021

Here’s a script that removes Oracle Java on your system. Installs OpenJDK Hotspot as a replacement.

#!/bin/bash
# set env
oracle_jre_version="jdk1.8.0_172"
open_jre_version="java-1.8.0-openjdk"
# REMOVE LINKS
deljdk () {
	sudo update-alternatives --remove "java" "/usr/lib/jvm/$oracle_jre_version/bin/java"
	sudo update-alternatives --remove "javac" "/usr/lib/jvm/$oracle_jre_version/bin/javac"
	sudo update-alternatives --remove "javaws" "/usr/lib/jvm/$oracle_jre_version/bin/javaws"
}
# REMOVE RPM
delrpm () {
	jdk=$(rpm -qa | grep jdk-1.7)
	rpm -e $jdk
	jdk=$(rpm -qa | grep jdk1.8)
	rpm -e $jdk
	sudo rm -rf /usr/java/jdk*
}
# REMOVE SYMBOLIC LINKS
delsym () {
	rm /usr/java/default /usr/java/latest
	rm /usr/lib/mozilla/plugins/libnpjp2.so
	rm /usr/lib/mozilla/plugins/libnpjp2.so
}
# INSTALL OPENJDK
addjdk () {
	cd /usr/java
	rm -f /usr/java/OpenJDK8U-jdk_x64_linux_hotspot_8u302b08.tar.gz
	wget --no-check-certificate https://10.49.39.125/download/OpenJDK8U-jdk_x64_linux_hotspot_8u302b08.tar.gz
	tar xzf OpenJDK8U-jdk_x64_linux_hotspot_8u302b08.tar.gz
	chown -R username:username /usr/java/jdk8u302-b08
}
# ADD PATH
addpath () {
	sed -i '/jdk8u302-b08/d' /home/username/.zshrc
	sed -i '/jdk8u302-b08/d' /home/username/.profile
	echo 'export PATH=/usr/java/jdk8u302-b08/bin:$PATH' | tee -a ~/.bashrc
	echo 'export PATH=/usr/java/jdk8u302-b08/bin:$PATH' | tee -a /home/username/.zshrc
	echo 'export PATH=/usr/java/jdk8u302-b08/bin:$PATH' | tee -a /home/username/.profile
	chown username:username /home/username/.zshrc
	chown username:username /home/username/.profile
}
deljdk
delrpm
delsym
addjdk
addpath

GCP Spot Instance

November 25, 2021

You can save anywhere from 60-91% using a spot instance. The downside is, the instance can be preempted anytime.

Create a spot instance.

gcloud beta compute instances create spot-example \
--provisioning-model=SPOT \
--instance-termination-action=STOP \
--image-project=ubuntu-os-cloud \
--image-family=ubuntu-2004-lts \
--machine-type=e2-micro \
--project=your-project-id \
--zone=us-central1-a

Delete instance.

gcloud compute instances delete spot-example \
--project=your-project-id \
--zone=us-central1-a

Delete lines using awk

November 5, 2021

Here’s how to delete a line from a file using awk.

awk '!/Redhat/' sample.txt > sample.tmp && mv sample.tmp sample.txt

The command above looks for ‘Redhat’ in a file and removes that line from the file.

You can add the line in the crontab to run at reboot if you like.

crontab -e

@reboot awk '!/Redhat/' sample.txt > sample.tmp && mv sample.tmp sample.txt

Bash Aliases

July 17, 2021

Create an alias.

alias gcloud='docker run --rm -ti --volumes-from gcloud-config google/cloud-sdk:latest gcloud'

Remove an alias.

unalias gcloud

Linux Delete User

January 6, 2021

Here’s how to delete a Linux user.

userdel username

Delete user and the home directory.

userdel -f username