Fabrice Quenneville
51c0b3312c
- **System Information**: - Added detailed commands for hardware and software information, including `lscpu`, `lshw`, `hwinfo`, and more. - Included commands for finding binary paths, counting words and lines in files. - **User Management**: - Introduced new sections for managing user information, super user management, and switching users. - Added commands for listing users, disabling root login via SSH, managing sudo permissions, and switching users with sudo or root privileges. This update provides a more comprehensive overview of system and user management tasks.
264 lines
5.4 KiB
Markdown
264 lines
5.4 KiB
Markdown
# Linux
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## Table of Contents
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- [Linux](#linux)
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- [Table of Contents](#table-of-contents)
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- [System Information](#system-information)
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- [Hardware Information](#hardware-information)
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- [Software Information](#software-information)
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- [User Management](#user-management)
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- [User Information](#user-information)
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- [Super User Management](#super-user-management)
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- [Switch User](#switch-user)
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- [USB Devices](#usb-devices)
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- [Test USB Key](#test-usb-key)
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## System Information
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### Hardware Information
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To gather detailed information about your hardware, use the following commands:
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- **`lscpu`**: Displays information about the CPU architecture, including details about cores, threads, and CPU family.
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- **`lshw`**: Provides a comprehensive listing of hardware components. Use `lshw -short` for a more concise view.
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- **`hwinfo`**: Offers detailed information about hardware components and can be more verbose than `lshw`.
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- **`lsscsi`**: Lists SCSI devices, including disks and other SCSI-attached hardware.
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- **`lsusb`**: Shows information about USB devices connected to your system.
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- **`lsblk`**: Lists block devices such as hard drives and their partitions.
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- **`df -H`**: Displays disk space usage in a human-readable format.
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- **`fdisk -l`**: Lists all partitions on the system.
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- **`dmidecode`**: Retrieves hardware information from the BIOS. Use:
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- `dmidecode -t processor` for CPU details
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- `dmidecode -t memory` for RAM details
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- `dmidecode -t bios` for BIOS information
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### Software Information
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**Finding Path to Binary**
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To find the location of an executable binary, use:
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```bash
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type composer
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```
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This command will show the path to the `composer` executable if it's available in your `PATH`.
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**Number of Words in a File**
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To count the number of words in a file, use:
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```bash
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wc filepath
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```
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This command will show the number of words along with other details like lines and characters.
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**Number of Lines in a File**
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To count the number of lines in a file, use:
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```bash
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wc -l filepath
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```
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This command will display the number of lines in the specified file.
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## User Management
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### User Information
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**List Users**
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To list all users from the `/etc/passwd` file, use:
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```bash
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awk -F':' '{ print $1}' /etc/passwd | sort
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```
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This command extracts the usernames from the `/etc/passwd` file and sorts them in alphabetical order.
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### Super User Management
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**Disable Root Login**
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To disable root login via SSH, perform the following steps:
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1. **Edit the SSH Configuration File:**
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```bash
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nano /etc/ssh/sshd_config
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```
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Comment out the line containing `PermitRootLogin` by adding a `#` at the beginning of the line.
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2. **Change Shell for Root User:**
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```bash
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nano /etc/passwd
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```
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Find the line starting with `root` and change `/bin/bash` to `/sbin/nologin` to disable login for the root user.
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Save and close the file. Restart the SSH service for changes to take effect:
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```bash
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systemctl restart ssh
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```
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**Sudo Management**
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**Add User to Sudo Group**
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```bash
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adduser fabrice sudo
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```
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**Update Sudoers File to Remove Password Requirement**
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Edit the sudoers file:
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```bash
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visudo
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```
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Add the following line to allow the user to execute commands without a password:
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```bash
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fabrice ALL=(ALL) NOPASSWD:ALL
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```
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### Switch User
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**Switch to Another User as Sudoer**
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```bash
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sudo -i -u postgres
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```
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This command switches to the `postgres` user with sudo privileges.
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**Switch to Another User as Root**
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```bash
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su - postgres
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```
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This command switches to the `postgres` user with root privileges.
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## USB Devices
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### Test USB Key
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**Device Information**
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Check if the system recognizes the device and show the latest system messages related to USB devices being connected:
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```bash
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lsusb
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dmesg | tail -n 20
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```
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**Find Mount Points and Device Information**
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Identify mount points, partitions, and other relevant details of mounted devices:
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```bash
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lsblk -f
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df -h | grep /dev/sdc
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findmnt /dev/sdc1
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mount | grep /dev/sd
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```
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**Print Detailed Information About the USB Key**
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View detailed partition and disk information:
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```bash
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fdisk -l /dev/sdc
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```
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**Test the File System**
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Check and repair the filesystem on the USB key:
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```bash
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fsck /dev/sdc1
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```
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**Test Data Integrity**
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Perform read/write tests to ensure the integrity of the USB key:
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1. **Unmount the USB Key** (if mounted):
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```bash
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umount /media/fabrice/BD48-F8BB
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```
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2. **Write Test**:
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```bash
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dd if=/dev/zero of=/dev/sdc bs=4M count=256 status=progress
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```
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3. **Read Test**:
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```bash
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dd if=/dev/sdc of=/dev/null bs=4M count=256 status=progress
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```
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**Check for Bad Blocks**
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Identify any bad sectors on the USB key:
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- **Read-only test**:
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```bash
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badblocks -v /dev/sdc
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```
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- **Non-destructive read-write test**:
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```bash
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badblocks -nsv /dev/sdc
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```
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- The `-n` option performs a non-destructive read-write test.
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- The `-s` option shows progress.
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- The `-v` option is for verbose output.
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**Perform a SMART Test**
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Run SMART diagnostics to test the health of the USB key:
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1. **Start a short SMART test**:
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```bash
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smartctl -t short /dev/sdc
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```
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2. **View test results**:
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```bash
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smartctl -a /dev/sdc
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```
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**Benchmark the Speed**
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Measure the read speed of the USB key:
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```bash
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hdparm -t /dev/sdc
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```
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**Unmount and Safely Remove**
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Unmount the USB key and safely remove it from the system:
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```bash
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umount /mnt/usb
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eject /dev/sdc
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```
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