CNIT 340 Exam 1

what is unix?

a collection of related operating systems

what are the two major divisions of unix?

BSD & SysV/SVR4

what kind of operating system is UNIX typically?

command line only

what is the structure of a UNIX command?

command -flags operand

what is the superuser account in UNIX?

root

what is the file and command that controls who can run programs as root

/etc/sudoers; visudo

T/F: is it possible to create a root equivalent account?

false

how does one interact with the system?

via the command line parser

what are some things the command line parser can do?

manage processes, manage files

what are the two ways commands can be entered?

manually and via shell scripting

login shell

program that provides the user's command line prompt when they log into the system

where is the login shell specified?

/etc/passwd

where are the startup scripts the login shell generally stored?

user's home directory

interactive shell

a non-login shell into which the user enters commands

non-interactive shell

usually contains a script and inherits environment variables from the parent shell

C shell (csh)

/bin/csh; uses C language syntax for scripting

Korn shell (ksh)

/bin/ksh; introduced command line history and tab completion

BASH

/bin/bash; standard scripting shell for most Linux distributions

what is everything managed as in UNIX?

a file under a single filesystem (root "/")

what is the only hard mount point in UNIX?

the root "/"

/bin directory

executable files requied for basic operations

/dev directory

placeholders for devices

/etc directory

configuration information and files

/sbin directory

system binaries

/lost+found directory

where lost files are put

/proc directory

holds the placeholders for running processes

/usr directory

contains installed applications used by all users

/home directory

contains the home directories for each user

/var directory

contains log files, spooling, and cache

/tmp directory

hold temporary files

what must happen before any filesystem (including CD-ROM) can be used?

it must be mounted to the root filesystem

mount point

directory used as an anchor point or place holder

where must filesystems be mounted over?

an existing directory/mount point

what is the command to mount a filesystem

mount

what is the command to unmount a filesystem

umount

what is the file that contains a list of all the filesystems to automatically mount?

/etc/fstab

what are the two partitions that every UNIX installation requires?

/ and swap

what is done during the installation filesystem configuration?

configuring disks for access, defining volumes, creating partitions and assigning filesystem to partitions

what partition should always be created separately?

/var

ls command

list the files characteristics and information

mv command

move a file or rename a file

rm command

remove a file

-f flag

force; prevents the system from asking confirmation before deleting

-r flag

recursive; affects all underlying files and directories

what are the three owners of every file/directory, in what order?

user, group, everyone

what is the command to view ownership?

ls -l

what is the command the change the user or group ownership?

chown

what is the command that will only change the group ownership?

chgrp

what are the three basic permissions?

read (4), write (2), execute (1)

what is the command to change file permissions?

chmod

what is the SUID bit?

a file always executes as the file's owner; value of 4, lower 's' when set and has read perm, upper 'S' when set and does not have read perm

what is the SGID bit?

any files will be executed as the owning group; any files created in the directory will have group ownership set to the parent directory's group; value of 2

what is the sticky bit?

only the owner/root of a file/directory can delete or rename the file; value of 1

link

a pointer to another file or directory

symbolic/soft links

a pointer to another file, if deleted the target remins

hard link

a direct link between the file, once the last reference to the inode is deleted, the file is no longer accessible

what link can cross the file system?

soft link

what link can link between directories?

soft link

what link has different inode number and file permissions?

soft link

what link will not have its permissions updated?

soft link

what link only contains the path of the original ifle?

soft link

what link cannot cross the file system boundaries?

hard link

what link cannot link between directories?

hard link

what link has the same inode number and permissions?

hard link

what link will have its permissions updated?

hard link

what link has the actual contents of the original file?

hard link

pipe ("|")

sends the output of a program as the input for another program

redirect (">")

redirect the output of a program to something other than stdout

grep command

used to search for a string; can use on file or whatever is piped into it

grep command structure (file)

grep

grap command structure (pipe)

| grep

find command

used to find files

find command structure

find -type -maxdepth -name

dircmp command

compares directories

ps command

lists all currently running processes

ps command structure

ps -aux OR ps aux

kill command

used to kill a currently running process

-9 flag

terminate with extreme prejudice

kill command structure

kill -9

command to reboot machine

shutdown -r now

command to halt/shutdown machine

shutdown -h 5

what are the two basic approaches to distributing UNIX software?

compile from source and pre-compiled packages

what are the steps to configure from source code?

./configure; make; make install

why compile from source code?

most flexible and will work on most UNIX distributions and hardware platforms, but have to deal with dependancies manually

why install software using packages?

automatic updates and don't have to worry about dependancies

what is a tarball

a file that contains multiple files; UNIX equivalent of a ZIP file

what is usually also done to tarballs?

compressed with gzip or bzip

what is the command to expand a tarball

tar -xvf

what is the command to expand a compressed tarball?

tar -zxvf

what is the ports collection?

automate downloading and compiling source code and handles dependencies, common on BSD, middleground between packages and compiling from source

where is hardware support done?

in the kernel

how does one add support for new hardware?

add to the kernel and recompile

what are the benefits of modular kernels

dynamically link new kernel modules to the kernel at run-time; faster, simpler, reduces system instability, more security issues

commands for interacting with kernel

depmod, modprobe, insmod

building kernel process

installer kernel sources/compilers, modify system config, build new kernel, install and test new kernel

UNIX startup process

BIOS -> boot device > boot loader > kernel > init/systemd

boot loader task

loads kernel into memory

kernel task

initialize hardware and modules

init/systemd task

check file system integrity, mount disks, initialize network and network daemons

fsck command

check the integrity of file systems