uname -r
More detailed information
uname -a
lsb_release -a
lsmod
lspci -k
dmesg
how to run python scripts: https://www.geeksforgeeks.org/how-to-schedule-python-scripts-as-cron-jobs-with-crontab/
create a new python script
#!/usr/bin/env python3
import time
import os
with open(os.path.expanduser('~/crontest.txt'),'a') as f:
f.write(time.ctime()+'\n')
chmod +x test.py
crontab -e
# m h dom mon dow command
* * * * * $HOME/test.py
/usr/share/applications/usr/share/icons.bashrc holds path variables.
ctrl-h hides and shows “dot” files in nautilus like .config or .ssh/
sudo passwd <username>
you may want to remove your keyring lock file as it doesn’t always update:
rm ~/.local/share/keyrings/login.keyring
ifconfig
ifconfig <network interface> down
ifconfig <network interface> up
ip link
ip addr
output current wifi name
sudo apt install -y wireless tools
iwgetid
iwgetid -r # just the name
iwlist wlan0 scan
sudo apt install -y network-manager
nmcli -f in-use,ssid,bssid,signal,bars dev wifi
list wifis
nmcli d wifi
connect to a specific wifi
nmcli d wifi connect XX:XX:XX:XX:XX:XX
https://askubuntu.com/questions/833905/how-can-i-connect-to-a-specific-bssid
sudo lsof -i:3389
apt install wavemon
wavemon
sudo nmcli network off
sudo nmcli network on
sudo netplan try
sudo netplan apply
links:
sudo apt list --installed <package-name-start*>
sudo apt --reinstall install <package>
dpkg --list | grep <package-name-fragment>
less /var/log/apt/history.log
These logs gets rotated (every month I guess), old files will be suffixed with a number and compressed. So to view the next history log, use:
zless /var/log/apt/history.log.1.gz
To view the logs available:
ls -la /var/log/apt/
from here
sudo libinput --list-devices
To change the file in place:
sed -i "s/regex/replace/" file
or
sed -i "s|regex|replace|" file
To copy output to a new file
sed "s/regex/replace/" filein > fileout
List all kernel images installed:
dpkg --list | grep linux-image
sudo reboot now
sudo shutdown now
gnome-session-quit
From https://fostips.com/lid-close-action-ubuntu-21-04-laptop/
edit /etc/systemd/logind.conf to configure power options such as lid closing opening,
HandleLidSwitch=ignore
HandleLidSwitchExternalPower=ignore
HandleLidSwitchDocked=ignore
systemctl restart systemd-logind.service
From:
Create a new group
sudo addgroup groupname
Create a new user
sudo adduser username
create a new group by gid
groupadd -g <group-id> <groupname>
create a new user and group by groupid
MYUSER=ubuntu
MYGID=1000
MYUID=1000
groupadd -g ${MYGID} ${MYUSER}
useradd -u ${MYUID} -g ${MYGID} -p $(perl -e 'print crypt($ARGV[0], "password")' 'password') -G adm,sudo ${MYUSER} && mkdir /home/${MYUSER} && chown ${MYUSER}:${MYUSER} /home/${MYUSER}
another variant:
useradd -m my_new_username -p $(openssl passwd my_custom_password) && usermod -s /bin/bash my_new_username && usermod -aG sudo,other_groups,another_group my_new_username
Find groups associated with current user:
groups $USER
Add new user to new groups
sudo usermod -aG adm username
sudo usermod -aG sudo username
#...
modify list of groups user belongs to
unlike the last command(-aG), -G redefines rather than appends
sudo usermod -G usergroup,othergroup username
passwd [username]
remove user from group
sudo deluser username groupname
remove user completely
sudo deluser --remove-home username
more tips here
groupdel <groupname>
passwd --expire <username_here>
from here
Expire Account
Let the account expire to disallowing a user from logging in from any source including ssh:
# disallow peter from logging in
sudo usermod --expiredate 1 peter
This is how you can reenable that account:
# set expiration date of peter to Never
sudo usermod --expiredate "" peter
users:
cut -d: -f1 /etc/passwd
getent passwd
groups:
cut -d: -f1 /etc/group
getent group
users
who
/bin /boot /etc /home /lib /lib64 /opt /root /sbin /usr /var
https://askubuntu.com/questions/222326/which-folders-to-include-in-backup
Based on this link
Might as well be fully updated first
sudo apt update
sudo apt upgrade
sudo shutdown -r now
edit which upgrade you want to do (lts or normal)
sudo nano /etc/update-manager/release-upgrades
change prompt=lts to prompt=normal
run updater
do-release-upgrade
you may need to indicate what to do with specific config files that get updated.
Restart
sudo shutdown -r now
from here
ifconfig
host myip.opendns.com resolver1.opendns.com
dig @resolver4.opendns.com myip.opendns.com +short
https://www.lifewire.com/find-a-mac-address-using-an-ip-address-818132
arp -a <ip address>
nmcli d wifi
to run something as root
sudo <command> [command options]
to run interactively as root
sudo -i
to run something as someone else
sudo -i -u <username>
run exit to leave that session
apt-mark showmanual
unset HISTFILE && exit
or
history -c && history -w && exit
https://www.cyberciti.biz/faq/clear-the-shell-history-in-ubuntu-linux/
apt policy
sudo add-apt-repository --remove ppa:PPA_Name/ppa
source: https://devconnected.com/how-to-count-files-in-directory-on-linux/
ls | wc -l
For example, if “Image Viewer” is in the name of the icon:
find / -name '*.desktop' -exec grep -H 'Image Viewer' {} \; 2>/dev/null
derived from here:
Some default locations listed here:
/usr/share/applications/gnome-terminal.desktop
~/.local/share/applications/gnome-terminal.desktop
~/.config/gnome-panel/launchers/gnome-terminal.desktop
~/.gnome/apps/gnome-terminal.desktop
sudo dmidecode
sudo dmidecode -t0 # BIOS
sudo dmidecode -t1 # System
sudo dmidecode -t2 # Board
sudo dmidecode -t3 # Enclosure or Chassis
sudo dmidecode -t4 # Processor
sudo dmidecode -t1 # System
Files can be stuck in ~/.local/share/Trash/expunged when you delete from Nautilus a folder that belongs to you, but contains files which are belong to another user, and it is tricky for Nautilus to handle this situation correctly. To delete them try to use:
sudo -i
rm -rv /home/<desired_user_name>/.local/share/Trash/expunged/*
exit
stat /path/to/filename
stat -c '%A %a %n' /path/to/filename
list disks with lsblk
lsblk -f #list filesystem details
lsblk -t #show topology
lsblk -i # use ascii
lsblk -o NAME,UUID # show specific columns
sudo lshw -class disk
sudo fdisk -l
sudo hwinfo --disk
ls -l /dev/disk/by-path
ls -l /dev/disk/by-id
get drive information:
sudo hdparm -I /dev/sda
if you have an NVMe device…
sudo apt install -y nvme-cli
nvme list
#sudo nvme smart-log <node_name>
sudo nvme smart-log /dev/nvme0n1
sudo nvme id-ctrl /dev/nvme0n1
From here
##list disks
sudo fdisk -l
#if you know the disk you want info about:
sudo fdisk -l /dev/sdd
sudo mount /dev/sdd1 /media/backup
# unmount
sudo umount /media/backup
# unmount all
sudo umount -a
# force unmount
sudo umount -f /media/backup
you can get most information from lsblk if you have temporarily mounted it…
#UUID=<yourUUID> <mount_location> <filesystem> <options> <dump(use 0)> <order(use 2)>
UUID=24df9215-550f-4ca0-a9f1-8f0efd2 /media/backup ext4 defaults 0 2
once you have edited, check by running
mount -a
from here
du -sh /path/to/my/dir
list directories, one level only, from here
du -h --max-depth 1 /path/to/my/dir
df -H
from here
tree /path/to/dir
from here
#chown -R <owner> <folder_1> <folder_2> ... <folder_n>
chown -R user /home/user
printenv | grep ROS
information on nautilus-aware mount locations
from here
sudo apt install -y cu
cu -l /dev/ttyACM0 -s 9600
To exit enter tilde dot (~.)
sudo apt install -y screen
screen /dev/ttyACM0 9600
From here
see the last few lines
#tail -100 <filename>
tail -100 history.txt
see real-time changes to files as they get appended:
tail -f history.txt
see line 196-200 of a file
head -200 history.txt | tail -5
see this page for more links
list login dates / times, users, etc
last
more info here
journalctl --list-boots
Will list all recent boots
journalctl --boot=<boot id>
To just get information about the most recent boot, use
journalctl -b
use pkexec to do things you would normally do with sudo, like
pkexec cp /path/to/sudo/backup /etc/sudoers
great advice from here: https://askubuntu.com/questions/438123/accidentally-deleted-etc-sudoers-file
nm-connection-editor
check out dd
sudo fdisk -l /dev/sdb
sudo dd if=/dev/sda of=~/sda.dd bs=128k status=progress conv=noerror,sync
sudo dd if=/dev/sda bs=128k status=progress conv=noerror,sync | gzip -c > /sda.gz
sudo dd if=/dev/sda of=/media/danaukes/24df9215-550f-4ca0-a9f1-8f0d666befd2/sda.dd bs=128k status=progress conv=noerror,sync
awk '{print $1}' <filename>