Add User

adduser silosix

Adds user with usermod

sudo usermod -aG usergroup username

sudo usermod -aG docker devuser

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User & Group Admin Commands

source: https://www.poftut.com/list-users-groups-linux/

Print Users, Home Dir, Shell

cat /etc/passwd

Names only

cat /etc/passwd | grep -v nologin

Print Users that have accessed system

cat /etc/passwd | grep -v nologin

Print Users with Home Dirs

cat /etc/passwd | grep "/home/" | awk -F':' '{ print 

Print Groups

cat /etc/group

Print Group Names

cat /etc/group | cut -d : -f 1

 

 

 

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adduser Help

mdp@pi:/ $ adduser --help
adduser [--home DIR] [--shell SHELL] [--no-create-home] [--uid ID]
[--firstuid ID] [--lastuid ID] [--gecos GECOS] [--ingroup GROUP | --gid ID]
[--disabled-password] [--disabled-login] [--add_extra_groups] USER
   Add a normal user

adduser --system [--home DIR] [--shell SHELL] [--no-create-home] [--uid ID]
[--gecos GECOS] [--group | --ingroup GROUP | --gid ID] [--disabled-password]
[--disabled-login] [--add_extra_groups] USER
   Add a system user

adduser --group [--gid ID] GROUP
addgroup [--gid ID] GROUP
   Add a user group

addgroup --system [--gid ID] GROUP
   Add a system group

adduser USER GROUP
   Add an existing user to an existing group

general options:
  --quiet | -q      don't give process information to stdout
  --force-badname   allow usernames which do not match the
                    NAME_REGEX configuration variable
  --help | -h       usage message
  --version | -v    version number and copyrigh

 

usermod Help

mdp@pi:/ $ usermod --help
Usage: usermod [options] LOGIN

Options:
  -c, --comment COMMENT         new value of the GECOS field
  -d, --home HOME_DIR           new home directory for the user account
  -e, --expiredate EXPIRE_DATE  set account expiration date to EXPIRE_DATE
  -f, --inactive INACTIVE       set password inactive after expiration
                                to INACTIVE
  -g, --gid GROUP               force use GROUP as new primary group
  -G, --groups GROUPS           new list of supplementary GROUPS
  -a, --append                  append the user to the supplemental GROUPS
                                mentioned by the -G option without removing
                                him/her from other groups
  -h, --help                    display this help message and exit
  -l, --login NEW_LOGIN         new value of the login name
  -L, --lock                    lock the user account
  -m, --move-home               move contents of the home directory to the
                                new location (use only with -d)
  -o, --non-unique              allow using duplicate (non-unique) UID
  -p, --password PASSWORD       use encrypted password for the new password
  -R, --root CHROOT_DIR         directory to chroot into
  -s, --shell SHELL             new login shell for the user account
  -u, --uid UID                 new UID for the user account
  -U, --unlock                  unlock the user account
  -v, --add-subuids FIRST-LAST  add range of subordinate uids
  -V, --del-subuids FIRST-LAST  remove range of subordinate uids
  -w, --add-subgids FIRST-LAST  add range of subordinate gids
  -W, --del-subgids FIRST-LAST  remove range of subordinate gids
  -Z, --selinux-user SEUSER     new SELinux user mapping for the user accoun