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Andrei Montchik edited this page Apr 29, 2024 · 22 revisions

System

  • Host information, kernel and OS version etc: hostnamectl
  • Shell type: echo %0
  • Review environment variables:
    • printenv
    • env
  • Reboot: sudo reboot
  • Latest restart time: uptime
  • All processes info: ps -ef or ps aux
  • Specific process info: ps -p <pid> -o pid,vsz=MEMORY -o user,group=GROUP -o comm,args=ARGS
  • Show the kernel message buffer since the latest reboot: dmesg -T

systemctl

  • Configuration location: /etc/systemd/system/
  • List of units: sudo systemctl list-units --all
    • Mark inactive units: sudo systemctl list-units --all --state=inactive

CPU

Memory

Disk

Network

Navigation and Search

  • Show only directories: ls -la | grep "^d"
  • Find file by name:
    • from current directory: find . -name "docker-compose*"
    • from the root: find / -name "docker-compose*"
  • Find the program location: which python3 or type -a python3 or command -v python3
  • Recursive search in current directory: grep -r "engine-migrations" .
  • Show just the file name containing the search string: grep -i -l setmarket *

Users and groups

  • Groups configuration location: /etc/group
  • List of groups: groups
  • Users in a group: grep docker /etc/group
  • Add user to a group: sudo usermod -a -G docker andrei
  • Add user to the sudoers file, use the sudo visudo editor.
  • Change owner recursively: sudo chown -R newuser:newgroup /mnt/data

SSH

  • Install openssh-server to allow SSH access, if it is not yet installed:
    1. sudo apt-get update
    2. sudo apt-get install openssh-server
    3. Start the server sudo service ssh start or sudo systemctl start ssh
  • Create the new user, add it to the sudoers group and re-login.
  • Configure SSH Keys for Authentication.
  • Disable password authentication.
  • Restrict user access to specific users or groups.
  • Disable the root access. Make sure to add your user to the sudo group first!

Archiving

  • Archive files: tar -cvzf archive.tar.gz file1 file2
  • Archive directory: tar -czvf archive-name.tar.gz /path/to/directory
  • View the archive contents: tar -tvf archive.tar.gz
  • Test the archive:
    • zst: zstd --test archive.tar.zst
  • Extract:
    • bz2 archive: tar -xjf archive.tar.bz2
    • gz archive: tar -xvf archive.tar.gz
    • zst archive: tar -I zstd -xvf archive.tar.zst
  • Install application from the .deb archive: sudo dpkg -i your-package-name.deb

Symbolic Links

  • Create symbolic link to file: ln -s ../../../../../cpp/common/messaging/sbe/me/me.xml .
  • Create symboli link to directory: ln -s /path/to/src_directory ~/symlink_directory

Data transfer

  • Copy file from host: scp andrei@64.233.160.01:/home/andrei/data/account_update.json .
  • Copy directory from host: scp -r sol@64.233.160.01:/home/andrei/data/ .
  • Copy file to network host: scp account_update.json andrei@64.233.160.01:/home/andrei/data
  • Copy directory to network host: scp -r data andrei@76.16.6.193:/tmp

Other

  • Generate UNIX Timestamp: date +%s
  • Rotate logs: logrotate /etc/logrotate.hourly.d/containers

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