ADV *NIX DAY 1-3 Flashcards by Dakota Edmunds

Utility to locate/print block device attributes.

blkid

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Desktop Management Interface. A tool for dumping a computer’s DMI table contents in a human-readable format.

dmidecode

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Print system information.

–a= all information

2.6.32-279
(2=kernel version, 6=Major revision, 32=Minor revision, 279= patch level & fixes)

uname

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Query and change the system host name and related settings.

hostnamectl (CentOS7)

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Change current run-level.

init

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Determine current run-level.

who -r

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Update and query run-level information for system services.

chkconfig

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Run SysV init scripts. Start, stop, restart or view the status of services in /etc/init.d

service (CentOS6)

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Query or send control commands to the systemd manager, to enable, disable, start, stop, or view the status of services.

systemctl (CentOS7)

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Create the list of operating systems to boot in GRUB’s menu interface.

/boot/grub/grub.conf

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init daemon configuration file, the initdefault line specifies what run-level starts at boot.

/etc/inittab

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User mode components may include:

processes and threads
windows manager
libraries
applications
shells
commands
utility programs

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Part of process management that shares CPU time between multiple LWPs.

scheduler

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Implements file and file system related interfaces provided to user.

VFS

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Elements of the Linux kernel that an architecture must use for normal operation and efficiency.

Architecture-dependent code

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Ensures the proper and timely execution of processes.

process management

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Provides an API to resources that send data across a network.

Network Subsystem

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Converts a process running in user mode to a protected kernel mode process.

SCI

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A program that provides the user CLI to the kernel.

Shell

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An instance of a program in execution.

process

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Contains the SCI and handles mapping between user requests and device driver actions. It also manages system resources and performs system services.

Kernel

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Computer programs used to perform certain tasks, functions, or activities and originate in user mode.

Application

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This mode includes processes such as shells, Linux commands, utilities, and user application programs.

User mode

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An implementation of the standard C library used by many operating systems and programs on those systems.

glibc

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When memory is exhausted and pages of memory are moved onto the disk.

swapping

A family of related standards specified by the IEEE that defines the API of a Unix OS.

POSIX

Run in user mode on top of a single kernel thread and shares address space and system resources.

LWP

A program that runs unobtrusively in the background rather than under the direct control of a user.

Daemon

This is a wrapper function for a Linux kernel system call.

library function

A low-level program allowing the kernel to communicate with a particular piece of hardware.

device driver

A catastrophic kernel crash that halts the entire PC.

kernel panic

Applications that make the OS work. (e.g., GUI, compilers, tools, and editors)

GNU Software

Displays file system type. (e.g., Ext, UFS, NTFS, ...)

blkid

Executed from /etc/rc.d/rc*.d and spawns a login.

Run level

Executes Kernel and initrd images.

Grub

Executes bootloader (GRUB).

MBR

Executes /sbin/init deamon.

Kernel

Executes run-level programs.

Init

Executes MBR

Bios

The file where the init daemon gets its instructions from.

/etc/inittab

Initial root file system with limited directories and executables.

Initrd

Linux process that spawns a login.

getty or mingetty

Command used to verify current run level.

who -r

Directory where master copies of the startup scripts reside.

/etc/init.d

Command used to change current run level.

init (command)

Command that updates and queries run level information for system services.

chkconfig

Command retrieves information from a listing of available shells in the /etc/shells file.

chsh

Command that provides a description of the system's hardware components.

dmidecode

More secure but less controllable system initialization manager.

systemd

Init manager where run-levels dictate the start up environment.

SysV

Modified SysV initialization manager, used by CentOS Version 6.

Upstart

Command that starts, stops, or restarts many services located in /etc/init.d.

service

Location of network-based services that fall in the xinetd category. (full path)

/etc/xinetd.d

Systemd command used to enable, start, stop, or disable services.

systemctl

Linux command used to view calls accessed during the execution of a command.

strace

Sets or prints the limits imposed on files written by the shell and its processes.

ulimit

Displays limits imposed on resources available to the current shell.

ulimit -a

Displays or sets core file size.

ulimit -c

Displays or sets max number of processes available to a single user.

ulimit -u

Similar to Windows Task Manager, this *nix tool is used to view system processes and their states.

Allows a device driver or any other kernel service to be linked into and removed from the kernel while it is running.

LKM

Linux command used to display a list of active LKMs.

lsmod

Command and option to display all kernel parameter values currently available.

sysctl -a

Command and option to change a sysctl value for current session.

sysctl -w

Command and option to load sysctl values from a file.

sysctl -p

Configuration file where user limits imposed on resources are set.

/etc/security/limits.conf

Linux file where all kernel values are loaded from at system boot.

/etc/sysctl.conf

Process interruption caused by some event external of and asynchronous to the current running process.

interrupt

Error or exception condition generated within current running process. Software written to catch an exception generated by the CPU.

trap

List three ways in which a process-level interrupt request can be sent:

terminal Administrator Kernel

Terminal interrupt (user hits interrupt keys).

SIGINT

Surest kill (cannot be trapped)

SIGKILL

Restarts a daemon

SIGHUP

Default termination signal used by kill command.

SIGTERM

Quit from terminal, process produces a core dump file.

SIGQUIT

``` process state: R S Z T ```

``` process state: Running Sleeping Zombie Suspended (stopped or terminated) ```

Command that reveals all file systems, disk space usage, and logical mount points in block size.

Displays or maps logical devices to mount points on a file system.

mount

What Linux command displays the disk’s physical partitioning scheme?

fdisk

A ______ is the basic file allocation unit for EXT(X). The size is defined in the superblock.

block

The allocation status of blocks (data) is determined using the block group’s ___________.

block bitmap

The allocation status of inodes is determined using the block group’s ___________.

inode bitmap

The _______ lists the blocks on the disk where the data is stored.

Inode Table

What command can be used to view the primary superblock?

dumpe2fs

What are the three timestamps associated with the EXT(X) filesystem?

modification access change

What are the three timestamps associated with the EXT(X) filesystem?

hardlink

What type of link file contains the pathname to another file?

symbolic link

What command is used to view file or file system status to include the access, change, and modify timestamps?

stat

is a simple data structure containing the filename and the inode address where the file's metadata can be found. This also contains a pointer to the next entry.

directory entry

ADV *NIX DAY 1-3 Flashcards

(89 cards)