리눅스 명령어

Change hostname (Reference Link)

sudo hostname new-server-name-here
sudo nano /etc/hosts
127.0.1.1 old-host-name
127.0.1.1 new-server-name-here

User management-Add/(un)Lock/Delete (Reference Link)

# add
sudo adduser [username]

# lock
sudo passwd -l username

# unlock
sudo passwd -u username

# delete 
sudo deluser [username]
# the deleted user's folder doesn't get deleted together.
# a new username that is the same as the deleted one can have the same file system.

# archive
sudo chown -R root:root /home/username/ # see below for chown
sudo mkdir /home/archived_users/
sudo mv /home/username /home/archived_users/

Group management (Reference Link)

# Get a list of groups
sudo getent group group

# Get the members of a group
groups [username]

# Get group members with IDs
id [username]

# Create a group
sudo addgroup [groupname]

# Add an existing user to a group
sudo adduser [username] [groupname]

# Change group of a user
sudo usermod -g [new_groupname] [username]

# Delete group
sudo delgroup [groupname]

/etc/passwd (Reference Link)

cat /etc/passwd
# list all the user accounts of the system
# each line, i.e., each user and separated by a colon (:), has seven fields.
# [username]:[password]:[user ID(UID)]:[group ID(GID)]:[User ID info]:[Home dir]:[Command/shell]
oracle:x:1021:1020:Oracle user:/data/network/oracle:/bin/bash

# [password]: shown as 'x' and encrypted passwords are in 
/etc/shadow 

chown

chown --help
Change the owner and/or group of each FILE to OWNER and/or GROUP
Usage: chown [OPTION]... [OWNER][:[GROUP]] FILE...
  or: chown [OPTION]... --reference=RFILE FILE...

  -R, --recursive        operate on files and directories recursively

chmod

Usage: chmod [OPTION]... MODE[,MODE]... FILE...
  or: chmod [OPTION]... OCTAL-MODE FILE...
  or: chmod [OPTION]... --reference=RFILE FILE...
Change the mode of each FILE to MODE.

  -R, --recursive        change files and directories recursively