# User Permissions > Linux user and permission management - **Type:** Skill - **Install:** `agentstack add skill-chaterm-terminal-skills-user-permissions` - **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior - **Seller:** [chaterm](https://agentstack.voostack.com/s/chaterm) - **Installs:** 0 - **Category:** [Cloud & Infrastructure](https://agentstack.voostack.com/c/cloud-infrastructure) - **Latest version:** 0.1.0 - **License:** Apache-2.0 - **Upstream author:** [chaterm](https://github.com/chaterm) - **Source:** https://github.com/chaterm/terminal-skills/tree/main/linux/user-permissions ## Install ```sh agentstack add skill-chaterm-terminal-skills-user-permissions ``` Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent. ## About # User and Permission Management ## Overview Linux user management, group management, sudo configuration, ACL permissions and other skills. ## User Management ### View Users ```bash # Current user whoami id # User information id username finger username # All users cat /etc/passwd getent passwd # Logged in users who w last # Login history ``` ### User Operations ```bash # Create user useradd username useradd -m -s /bin/bash username # Create home directory, specify shell useradd -G group1,group2 username # Specify supplementary groups # Modify user usermod -aG groupname username # Add to group usermod -s /bin/zsh username # Change shell usermod -L username # Lock user usermod -U username # Unlock user # Delete user userdel username userdel -r username # Also delete home directory # Change password passwd username passwd -l username # Lock password passwd -u username # Unlock password chage -l username # View password policy ``` ## Group Management ### View Groups ```bash # User's groups groups username id -Gn username # All groups cat /etc/group getent group # Group members getent group groupname ``` ### Group Operations ```bash # Create group groupadd groupname groupadd -g 1001 groupname # Specify GID # Modify group groupmod -n newname oldname # Rename # Delete group groupdel groupname # Manage group members gpasswd -a username groupname # Add user gpasswd -d username groupname # Remove user gpasswd -M user1,user2 groupname # Set member list ``` ## sudo Configuration ### Basic Usage ```bash # Execute as root sudo command sudo -i # Switch to root shell sudo -u username command # Execute as another user # View permissions sudo -l ``` ### sudoers Configuration ```bash # Edit sudoers (recommended method) visudo # Or edit files under /etc/sudoers.d/ visudo -f /etc/sudoers.d/username ``` ### Common Configuration Examples ```bash # /etc/sudoers.d/username # Full privileges username ALL=(ALL:ALL) ALL # No password required username ALL=(ALL) NOPASSWD: ALL # Specific commands username ALL=(ALL) /usr/bin/systemctl restart nginx # Specific commands without password username ALL=(ALL) NOPASSWD: /usr/bin/docker # Group privileges %groupname ALL=(ALL) ALL ``` ## ACL Permissions ### View ACL ```bash getfacl file getfacl -R dir # Recursive view ``` ### Set ACL ```bash # Set user permissions setfacl -m u:username:rwx file setfacl -m u:username:rx dir # Set group permissions setfacl -m g:groupname:rx file # Set default ACL (new files inherit) setfacl -d -m u:username:rwx dir # Recursive set setfacl -R -m u:username:rx dir # Remove ACL setfacl -x u:username file # Remove specific setfacl -b file # Remove all ``` ## Special Permissions ### SUID/SGID/Sticky ```bash # SUID (4) - Execute as file owner chmod u+s file chmod 4755 file # SGID (2) - Execute as file group/directory inherits group chmod g+s file chmod 2755 dir # Sticky (1) - Only owner can delete chmod +t dir chmod 1777 dir # View ls -la # -rwsr-xr-x SUID # -rwxr-sr-x SGID # drwxrwxrwt Sticky ``` ## Common Scenarios ### Scenario 1: Create Developer User ```bash # Create user and group groupadd developers useradd -m -s /bin/bash -G developers devuser # Set password passwd devuser # Configure sudo echo "devuser ALL=(ALL) NOPASSWD: /usr/bin/docker, /usr/bin/systemctl" > /etc/sudoers.d/devuser chmod 440 /etc/sudoers.d/devuser ``` ### Scenario 2: Shared Directory Permissions ```bash # Create shared directory mkdir /shared groupadd shared chown root:shared /shared chmod 2775 /shared # SGID ensures new files inherit group # Add users to group usermod -aG shared user1 usermod -aG shared user2 ``` ### Scenario 3: Restrict User to Specific Commands ```bash # /etc/sudoers.d/limited-user limited ALL=(ALL) NOPASSWD: /usr/bin/systemctl status *, /usr/bin/journalctl ``` ## Troubleshooting | Problem | Solution | |---------|----------| | sudo permission denied | Check `/etc/sudoers.d/` configuration | | User cannot login | Check shell, password lock status | | Group permissions not working | Re-login or `newgrp groupname` | | ACL not working | Check if filesystem supports ACL | ## Source & license This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code. - **Author:** [chaterm](https://github.com/chaterm) - **Source:** [chaterm/terminal-skills](https://github.com/chaterm/terminal-skills) - **License:** Apache-2.0 Install and usage instructions live in the source repository linked above. ## Pricing - **Free** — Free ## Security capabilities Automated source analysis of v0.1.0 — what this tool can access: - **Network access:** no - **Filesystem access:** no - **Shell / process execution:** no - **Environment & secrets:** no - **Dynamic code execution:** no *"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.* ## Versions - **0.1.0** — security scan: passed — Imported from the upstream source. ## Links - Listing page: https://agentstack.voostack.com/l/skill-chaterm-terminal-skills-user-permissions - Seller: https://agentstack.voostack.com/s/chaterm - Browse the marketplace: https://agentstack.voostack.com/browse --- Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.