user-permissions

Name: user-permissions
Author: chaterm

54installs12forks

How to install user-permissions?

chaterm/terminal-skills/user-permissions

$npx -y skills add chaterm/terminal-skills --skill user-permissions

Installs into the current project.

Summary

Linux user and permission management

Files · 1

View on GitHub

SKILL.md

1	# User and Permission Management
2
3	## Overview
4	Linux user management, group management, sudo configuration, ACL permissions and other skills.
5
6	## User Management
7
8	### View Users
9	```bash
10	# Current user
11	whoami
12	id
13
14	# User information
15	id username
16	finger username
17
18	# All users
19	cat /etc/passwd
20	getent passwd
21
22	# Logged in users
23	who
24	w
25	last # Login history
26	```
27
28	### User Operations
29	```bash
30	# Create user
31	useradd username
32	useradd -m -s /bin/bash username # Create home directory, specify shell
33	useradd -G group1,group2 username # Specify supplementary groups
34
35	# Modify user
36	usermod -aG groupname username # Add to group
37	usermod -s /bin/zsh username # Change shell
38	usermod -L username # Lock user
39	usermod -U username # Unlock user
40
41	# Delete user
42	userdel username
43	userdel -r username # Also delete home directory
44
45	# Change password
46	passwd username
47	passwd -l username # Lock password
48	passwd -u username # Unlock password
49	chage -l username # View password policy
50	```
51
52	## Group Management
53
54	### View Groups
55	```bash
56	# User's groups
57	groups username
58	id -Gn username
59
60	# All groups
61	cat /etc/group
62	getent group
63
64	# Group members
65	getent group groupname
66	```
67
68	### Group Operations
69	```bash
70	# Create group
71	groupadd groupname
72	groupadd -g 1001 groupname # Specify GID
73
74	# Modify group
75	groupmod -n newname oldname # Rename
76
77	# Delete group
78	groupdel groupname
79
80	# Manage group members
81	gpasswd -a username groupname # Add user
82	gpasswd -d username groupname # Remove user
83	gpasswd -M user1,user2 groupname # Set member list
84	```
85
86	## sudo Configuration
87
88	### Basic Usage
89	```bash
90	# Execute as root
91	sudo command
92	sudo -i # Switch to root shell
93	sudo -u username command # Execute as another user
94
95	# View permissions
96	sudo -l
97	```
98
99	### sudoers Configuration
100	```bash
101	# Edit sudoers (recommended method)
102	visudo
103
104	# Or edit files under /etc/sudoers.d/
105	visudo -f /etc/sudoers.d/username
106	```
107
108	### Common Configuration Examples
109	```bash
110	# /etc/sudoers.d/username
111
112	# Full privileges
113	username ALL=(ALL:ALL) ALL
114
115	# No password required
116	username ALL=(ALL) NOPASSWD: ALL
117
118	# Specific commands
119	username ALL=(ALL) /usr/bin/systemctl restart nginx
120
121	# Specific commands without password
122	username ALL=(ALL) NOPASSWD: /usr/bin/docker
123
124	# Group privileges
125	%groupname ALL=(ALL) ALL
126	```
127
128	## ACL Permissions
129
130	### View ACL
131	```bash
132	getfacl file
133	getfacl -R dir # Recursive view
134	```
135
136	### Set ACL
137	```bash
138	# Set user permissions
139	setfacl -m u:username:rwx file
140	setfacl -m u:username:rx dir
141
142	# Set group permissions
143	setfacl -m g:groupname:rx file
144
145	# Set default ACL (new files inherit)
146	setfacl -d -m u:username:rwx dir
147
148	# Recursive set
149	setfacl -R -m u:username:rx dir
150
151	# Remove ACL
152	setfacl -x u:username file # Remove specific
153	setfacl -b file # Remove all
154	```
155
156	## Special Permissions
157
158	### SUID/SGID/Sticky
159	```bash
160	# SUID (4) - Execute as file owner
161	chmod u+s file
162	chmod 4755 file
163
164	# SGID (2) - Execute as file group/directory inherits group
165	chmod g+s file
166	chmod 2755 dir
167
168	# Sticky (1) - Only owner can delete
169	chmod +t dir
170	chmod 1777 dir
171
172	# View
173	ls -la
174	# -rwsr-xr-x SUID
175	# -rwxr-sr-x SGID
176	# drwxrwxrwt Sticky
177	```
178
179	## Common Scenarios
180
181	### Scenario 1: Create Developer User
182	```bash
183	# Create user and group
184	groupadd developers
185	useradd -m -s /bin/bash -G developers devuser
186
187	# Set password
188	passwd devuser
189
190	# Configure sudo
191	echo "devuser ALL=(ALL) NOPASSWD: /usr/bin/docker, /usr/bin/systemctl" > /etc/sudoers.d/devuser
192	chmod 440 /etc/sudoers.d/devuser
193	```
194
195	### Scenario 2: Shared Directory Permissions
196	```bash
197	# Create shared directory
198	mkdir /shared
199	groupadd shared
200	chown root:shared /shared
201	chmod 2775 /shared # SGID ensures new files inherit group
202
203	# Add users to group
204	usermod -aG shared user1
205	usermod -aG shared user2
206	```
207
208	### Scenario 3: Restrict User to Specific Commands
209	```bash
210	# /etc/sudoers.d/limited-user
211	limited ALL=(ALL) NOPASSWD: /usr/bin/systemctl status *, /usr/bin/journalctl
212	```
213
214	## Troubleshooting
215
216	\| Problem \| Solution \|
217	\|---------\|----------\|
218	\| sudo permission denied \| Check `/etc/sudoers.d/` configuration \|
219	\| User cannot login \| Check shell, password lock status \|
220	\| Group permissions not working \| Re-login or `newgrp groupname` \|
221	\| ACL not working \| Check if filesystem supports ACL \|

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user-permissions

54installs12forks

View on GitHub

How to install user-permissions?

chaterm/terminal-skills/user-permissions

$npx -y skills add chaterm/terminal-skills --skill user-permissions

Installs into the current project.

Summary

Linux user and permission management

Files · 1

View on GitHub

SKILL.md

1	# User and Permission Management
2
3	## Overview
4	Linux user management, group management, sudo configuration, ACL permissions and other skills.
5
6	## User Management
7
8	### View Users
9	```bash
10	# Current user
11	whoami
12	id
13
14	# User information
15	id username
16	finger username
17
18	# All users
19	cat /etc/passwd
20	getent passwd
21
22	# Logged in users
23	who
24	w
25	last # Login history
26	```
27
28	### User Operations
29	```bash
30	# Create user
31	useradd username
32	useradd -m -s /bin/bash username # Create home directory, specify shell
33	useradd -G group1,group2 username # Specify supplementary groups
34
35	# Modify user
36	usermod -aG groupname username # Add to group
37	usermod -s /bin/zsh username # Change shell
38	usermod -L username # Lock user
39	usermod -U username # Unlock user
40
41	# Delete user
42	userdel username
43	userdel -r username # Also delete home directory
44
45	# Change password
46	passwd username
47	passwd -l username # Lock password
48	passwd -u username # Unlock password
49	chage -l username # View password policy
50	```
51
52	## Group Management
53
54	### View Groups
55	```bash
56	# User's groups
57	groups username
58	id -Gn username
59
60	# All groups
61	cat /etc/group
62	getent group
63
64	# Group members
65	getent group groupname
66	```
67
68	### Group Operations
69	```bash
70	# Create group
71	groupadd groupname
72	groupadd -g 1001 groupname # Specify GID
73
74	# Modify group
75	groupmod -n newname oldname # Rename
76
77	# Delete group
78	groupdel groupname
79
80	# Manage group members
81	gpasswd -a username groupname # Add user
82	gpasswd -d username groupname # Remove user
83	gpasswd -M user1,user2 groupname # Set member list
84	```
85
86	## sudo Configuration
87
88	### Basic Usage
89	```bash
90	# Execute as root
91	sudo command
92	sudo -i # Switch to root shell
93	sudo -u username command # Execute as another user
94
95	# View permissions
96	sudo -l
97	```
98
99	### sudoers Configuration
100	```bash
101	# Edit sudoers (recommended method)
102	visudo
103
104	# Or edit files under /etc/sudoers.d/
105	visudo -f /etc/sudoers.d/username
106	```
107
108	### Common Configuration Examples
109	```bash
110	# /etc/sudoers.d/username
111
112	# Full privileges
113	username ALL=(ALL:ALL) ALL
114
115	# No password required
116	username ALL=(ALL) NOPASSWD: ALL
117
118	# Specific commands
119	username ALL=(ALL) /usr/bin/systemctl restart nginx
120
121	# Specific commands without password
122	username ALL=(ALL) NOPASSWD: /usr/bin/docker
123
124	# Group privileges
125	%groupname ALL=(ALL) ALL
126	```
127
128	## ACL Permissions
129
130	### View ACL
131	```bash
132	getfacl file
133	getfacl -R dir # Recursive view
134	```
135
136	### Set ACL
137	```bash
138	# Set user permissions
139	setfacl -m u:username:rwx file
140	setfacl -m u:username:rx dir
141
142	# Set group permissions
143	setfacl -m g:groupname:rx file
144
145	# Set default ACL (new files inherit)
146	setfacl -d -m u:username:rwx dir
147
148	# Recursive set
149	setfacl -R -m u:username:rx dir
150
151	# Remove ACL
152	setfacl -x u:username file # Remove specific
153	setfacl -b file # Remove all
154	```
155
156	## Special Permissions
157
158	### SUID/SGID/Sticky
159	```bash
160	# SUID (4) - Execute as file owner
161	chmod u+s file
162	chmod 4755 file
163
164	# SGID (2) - Execute as file group/directory inherits group
165	chmod g+s file
166	chmod 2755 dir
167
168	# Sticky (1) - Only owner can delete
169	chmod +t dir
170	chmod 1777 dir
171
172	# View
173	ls -la
174	# -rwsr-xr-x SUID
175	# -rwxr-sr-x SGID
176	# drwxrwxrwt Sticky
177	```
178
179	## Common Scenarios
180
181	### Scenario 1: Create Developer User
182	```bash
183	# Create user and group
184	groupadd developers
185	useradd -m -s /bin/bash -G developers devuser
186
187	# Set password
188	passwd devuser
189
190	# Configure sudo
191	echo "devuser ALL=(ALL) NOPASSWD: /usr/bin/docker, /usr/bin/systemctl" > /etc/sudoers.d/devuser
192	chmod 440 /etc/sudoers.d/devuser
193	```
194
195	### Scenario 2: Shared Directory Permissions
196	```bash
197	# Create shared directory
198	mkdir /shared
199	groupadd shared
200	chown root:shared /shared
201	chmod 2775 /shared # SGID ensures new files inherit group
202
203	# Add users to group
204	usermod -aG shared user1
205	usermod -aG shared user2
206	```
207
208	### Scenario 3: Restrict User to Specific Commands
209	```bash
210	# /etc/sudoers.d/limited-user
211	limited ALL=(ALL) NOPASSWD: /usr/bin/systemctl status *, /usr/bin/journalctl
212	```
213
214	## Troubleshooting
215
216	\| Problem \| Solution \|
217	\|---------\|----------\|
218	\| sudo permission denied \| Check `/etc/sudoers.d/` configuration \|
219	\| User cannot login \| Check shell, password lock status \|
220	\| Group permissions not working \| Re-login or `newgrp groupname` \|
221	\| ACL not working \| Check if filesystem supports ACL \|

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