System Administration Flashcards

Which command updates the initramfs image on an Ubuntu/Debian system?

Answer: update-initramfs -u

`update-initramfs -u` rebuilds the initramfs for the current kernel on Debian-based systems.

What is the purpose of the `chroot` command?

Answer: Change the apparent root directory for a process

`chroot` runs a command with a specified directory as the apparent filesystem root, isolating it from the real root.

Which file controls the maximum number of open file descriptors system-wide on a Linux system?

Answer: /proc/sys/fs/file-max

`/proc/sys/fs/file-max` holds the system-wide maximum number of open file descriptors the kernel allows.

You need to zero out a disk before decommissioning it securely. Which command is appropriate?

Answer: shred -vz /dev/sdX

`shred -vz` overwrites the device multiple times and then zeros it, making data recovery very difficult.

What does `ss -s` display?

Answer: A summary of socket statistics by protocol

`ss -s` prints a summary showing the total number of sockets broken down by type and state.

Which command would you use to check the SMART status of a hard drive `/dev/sda`?

Answer: smartctl -a /dev/sda

`smartctl -a` from the `smartmontools` package reads and displays all SMART data for the specified drive.

What is the function of `PAM` (Pluggable Authentication Modules) in Linux?

Answer: A flexible framework that decouples authentication from application logic

PAM provides a centralized, configurable authentication framework so applications don't need to implement auth directly.