Uly.me

cloud engineer

linux

Memory Info on Linux

Here’s how to view system memory on Linux.

Default display is in kB

cat /proc/meminfo
MemTotal:        7492768 kB
MemFree:          427368 kB
MemAvailable:    5424768 kB

Display in MB

awk '$3=="kB"{$2=$2/1024;$3="MB"} 1' /proc/meminfo | column -t
MemTotal:           7317.16      MB
MemFree:            404.527      MB
MemAvailable:       5285.4       MB

Output in GB

awk '$3=="kB"{$2=$2/1024^2;$3="GB";} 1' /proc/meminfo | column -t
MemTotal:           7.14566      GB
MemFree:            0.370392     GB
MemAvailable:       5.13733      GB

Rocky Linux in a Container

Here’s how to run Rocky Linux in a Docker container.

Download the image.

docker pull rockylinux/rockylinux

Create a Rocky Linux container called bullwinkle.

docker run -it --name bullwinkle -d rockylinux/rockylinux

Login to the container using bash.

docker exec -it --user root bullwinkle /bin/bash

When done, stop and delete the container.

docker ps -a
docker stop container_ID
docker rm container_ID

Useradd With Specific uid and guid

Here’s the command to create a Linux user with a specific user id and group id.

sudo groupadd -r -g 1234567 username
sudo useradd -r -u 1234567 -g 1234567 -m -d /home/username -s /bin/bash nexus -c "my new account"

Printing From A Terminal

There are times you just want to print directly from the command line.

# check your printing options
lpotions
lpinfo -v
# what's your default printer
lpinfo -p -d
# use lp to print
lp notes.txt
# use -n print multiple copies
lp -n 2 notes.txt
# check the printer queue
lp -q
# use the job number to cancel print jobs if needed
cancel 123

Linux Prompt

Here’s my favorite Linux prompt.

PS1='\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '

Add to end of your .bashrc to make it permanent.