Commands¶

SSL Certificates¶

Verify¶

openssl verify cert.pem
openssl verify -untrusted ca-bundle cert.pem

Certbot¶

WildCard Certificates

AMI2 Certificates Automation

Issue - No module named cryptography

Folders¶

Create Multiple Folders

mkdir -p {networking,compute,storage}

Create Multiple Files in Multiple Folders

touch {networking,compute,storage}/{main.tf,variables.tf,outputs.tf}

Services¶

Journalctl¶

journalctl -u kubelet.service
journalctl # All
journalctl -b # Last Boot
journalctl -b 1 # Before Last Boot
journalctl --since "2 days ago"
vi /etc/system.d/journald.conf # Config Files

Inodes¶

Get File Inode

ls -i /etc/passwd

Find File by Inode

find / -inum 55116 /etc/passwd

Get Inodes Available

df -i

Disk Space¶

du -h

du -s # To sum the total

du -s /

du -h --max-depth=1 # Show the disk usage by folder, and not the sub dirs because of Depth = 1

Tar¶

# List files without extract
tar -tvf etcd-v3.3.13-linux-amd64.tar.gz

# Extract only one file
tar -xvf etcd-v3.3.13-linux-amd64.tar.gz etcd-v3.3.13-linux-amd64/etcdctl

Filesystem¶

fsck (filesystem check)¶

To check errors from filesystem
Don't do in mounted filesystem

sudo fsck /dev/sdb1
sudo umount /dev/sdb1

dumpe2fs¶

Get info about filesystem

sudo dumpe2fs -h /dev/sdb1

tune2fs¶

To get info and tune filesystem

tune2fs -l /dev/xvda1

Set Volume Name

tune2fs -L Photos /dev/xvda1

Set mount counts will be filesystem checked

tune2fs -c 10 /dev/xvda1

fuser¶

Show which process is using the directory

# fuser /mount/Photos
/mount/Photos:              3157c

# ps aux | grep 3157
-- Will see the process, probably /bin/bash

# ps auxf  -> Show which command executed and the login session called

Kernel Modules¶

# To view who use the modules
lsmod

# To remove
sudo rmmod video

# To enable
sudo modprobe video

Libs¶

# Get Shared libs location
cat /etc/ld.so.conf

# To load new lib
ldconfig

# Change Library Path temporary
export LD_LIBRARY_PATH=/home/nick/lib

# Print shared libs from app
ldd /bin/ls

Hardware¶

List pci Devices

lspci
lspci -v
lspci -vvv

Syslog¶

Config Files

cd /etc/rsyslog.d/

Rotate Files Conf

vi /etc/logrotate.conf