| groupadd group_name |
create a new group |
| groupdel group_name |
delete a group |
| groupmod -n new_group_name old_group_name |
rename a group |
| useradd -c "Nome Cognome" -g admin -d /home/user1 -s /bin/bash user1 |
create a new user belongs "admin" group |
| useradd user1 |
create a new user |
| userdel -r user1 |
delete a user ( '-r' eliminates home directory) |
| usermod -c "User FTP" -g system -d /ftp/user1 -s /bin/nologin user1 |
change user attributes |
| passwd |
change password |
| passwd user1 |
change a user password (only by root) |
| chage -E 2005-12-31 user1 |
set deadline for user password |
| pwck |
check correct syntax and file format of '/etc/passwd' and users existence |
| grpck |
check correct syntax and file format of '/etc/group' and groups existence |
| newgrp group_name |
log in to a new group to change default group of newly created files |