Intro
Intro
Create and modify accounts, password aging, groups, and privilege elevation. Prefer sudo for policy-controlled admin work; use account tools carefully on production identity stores.
Commands in this part
| Command | Role |
|---|---|
sudo |
sudo runs a command as another user (default: root) according to policy in /etc/sudoers and /etc/sudoers.d/*. |
visudo |
visudo safely edits the sudoers configuration (/etc/sudoers and files under /etc/sudoers.d/). |
useradd |
useradd creates a new user account and related system entries (/etc/passwd, /etc/shadow, /etc/group as needed). |
usermod |
usermod modifies an existing user account: shell, home, groups, UID, lock state, expiry, and more. |
userdel |
userdel deletes a user account from the system. |
passwd |
passwd sets or changes user passwords and can lock/unlock accounts or expire passwords. |
chage |
chage (change age) views and modifies password aging policy for a user: last change date, minimum/maximum days… |
groupadd |
groupadd creates a new group entry in the local group database (/etc/group, and /etc/gshadow when used). |
groupmod |
groupmod modifies an existing group: rename it, change its GID, or adjust related attributes depending on the… |
groupdel |
groupdel deletes a group from the system group database (typically /etc/group and /etc/gshadow). |
getent |
getent queries Name Service Switch (NSS) databases—the same view applications get via glibc: local files, LDAP/SSSD,… |
su |
su (“substitute user”) starts a shell or runs a command as another user. |
Suggested starting points
- Elevation:
sudo,visudo,su. - Accounts:
useradd/usermod/userdel,passwd,chage. - Groups:
groupadd/groupmod/groupdel. - Lookups:
getent(works with NSS/LDAP backends, not only local files).