Linux

Front 1

list files

- long listing

- displays inode number in the first field

- displays number on file system blocks used by file

-list all files including invisible files

Back 1

ls

-l

-i

-s

-a

Front 2

displays on-line manual pages about command

Back 2

man

Front 3

clears the current screen, giving you an emtpy terminal window

Back 3

clear

Front 4

displays text files a page at a time

allows backward movement, one page at a time

initiates a search for a string

exits from less

advances one screen at a time

advances one line at a time

Back 4

less

b

/

q

spacebar

enter

Front 5

searches a file or files for lines that contain strings of a certain pattern

Back 5

grep

Front 6

creates a new user or updates default new user information

specifies path of the user's home directory

makes a home directory if one does not already exist

assigns whatever group is in the default

Back 6

useradd

-d

-m

-n

Front 7

deletes a user account

removes home directory for specified user

Back 7

userdel

-r

Front 8

enables a user to change their password or for the administrator to set and modify password settings

Back 8

passwd

Front 9

switch user

Back 9

su

Front 10

used for authentication and authorization

Back 10

etc/passwd

Front 11

used for authentication

Back 11

etc/shadow

Front 12

used for authorization

Back 12

etc/group

Front 13

/etc/passwd File

Back 13

1. User Account Name

2. Placeholder for hashed password

3. User Identification Number

4. Group Identification Number

5. Comments

6. User's Home Directory

7. User's Default Shell

Front 14

/etc/shadow File

Back 14

1. User Account Name

2. Hashed Password

3. Number of days between 01Jan1970 and last modification date - when last changed.

4. Minimum number of days between password changes.

5. Maximum number of days a password is valid.

6. Number of warning days until is user is required to change password

7. Number of days after password expires, account is disabled/inactive

8. Number of days from 01Jan1970 until account expires

Front 15

/etc/group File

Back 15

1. Group Name

2. Placeholder for encrypted password

3. Group ID number

4. Users who have this group as a supplementary group

Front 16

when user logs onto system for first time and doesn't have a profile, default settings

Back 16

/etc/profile

Front 17

Users customize their environment/profile by modifying

Back 17

~/.bash_profile

Front 18

System administration and configuration files

Back 18

/etc

Front 19

Current working directory

Back 19

pwd

Front 20

view the path statement

modify path statement

Back 20

echo

PATH=$PATH:

Front 21

creates a typescript of the terminal session

Back 21

script

Front 22

prints system information

- prints all information

Back 22

uname

-a

Front 23

list directory contents in a tree-like format

Turn colorization on always

Append a "/" for directories

Back 23

tree

-C

-F

Front 24

creates an empty file

- manipulates files access date/time stamp

Back 24

touch

-t

Front 25

creates link between files or directories

-creates symbolic link to another file

Back 25

ln

-s

Front 26

creates one or more directories

- creates a directory where no parent directory exist

Back 26

mkdir

-p

Front 27

copies to a file or copies multiple files to a directory

- recusively copies directories

Back 27

cp

-R

Front 28

Moves or renames files and directories

Back 28

mv

Front 29

removes an empty directory

Back 29

rmdir

Front 30

removes a file

- removies a directory and its contents recursively

-ignores nonexistent files, never prompt

Back 30

rm

-r

-f

Front 31

creates or edits a text file

Back 31

vi <filename>

Front 32

displays the contents one screen at a time

Back 32

more

Front 33

called pipe, passes the output of one command to the input of another

Back 33

|

Front 34

displays the first 10 lines of a file by default

Back 34

head <filename>

Front 35

displays the last 10 lines of a file by default

Back 35

tail <filename>

Front 36

displays file(s) conctents to the screen and can concatenate (combine) files

Back 36

cate <filename> <other_filename>

Front 37

redirects standard output to a file. If the file does not exist, it is created. If the file does exist, it is overwritten

Back 37

>

ex: cat <filename1> <filename2> > <bothfiles>

Front 38

Appends standard output to the end of another file. If the file does not exist, it is created.

Back 38

>>

ex: cat <filename1> >> <new file>

Front 39

locates files having certain characteristics, which are specified

Back 39

find

Front 40

displays the full path <location) of most (shell) commands

Back 40

which <command>

Front 41

Displays a snapshot status of all active processes the terminal controls

- list information about every process running

- present in a long format

- generates a list in full mode format

Back 41

ps

-e

-l

Front 42

stops a process from running using its PID

- used to kill a stubborn process that won't die

Back 42

kill

- -9

ex: pkill -9 <PID>

Front 43

stops a process from running using its process name

- used to kill a stubborn process that won't die

- Used to immediately re-spawn a process to effect configuration changes.

Back 43

pkill

- -9

-HUP

Front 44

maintains a history file of all successfully run commands by a particular user

Back 44

history

Front 45

determines file type

Back 45

file

Front 46

prints the strings of printable characters in a file.

Back 46

strings <filename>

Front 47

displays the user who is logged in

Back 47

whoami

Front 48

displays user login information including login name, timer, terminal, and more

Back 48

who

Front 49

displays information about the user logged in and what they are doing

Back 49

w

Front 50

prints or sets the system date and/or time

- sets the date to the date and time provided

Back 50

date

-s

Front 51

Tape archive utility used to archive files to tape or disk

- create

- list table contents of tar file

- extract, must be in target directory to extract

- verbose, list each file as tar reads/writes

- read/write to or from file

Back 51

tar

c

t

x

v

f

Front 52

compresses files and saves the with a .gz file extension

Back 52

gzip

Front 53

this utility decompresses a file which was compressed with gzip

Back 53

gunzip

Front 54

this utility compresses files and saves them with a .bz2 file extension

Back 54

bzip2

Front 55

this utility decompresses a file which was compressed with bzip2

Back 55

bunzip2

Front 56

schedules a job/process for a one-time execution

Back 56

at <schedule time>

Front 57

list users pending jobs

Back 57

atq

Front 58

deletes user's jobs identified by job number

Back 58

atrm

Front 59

schedules periodic jobs

-edit

-list

Back 59

crontab

-e

-l

Front 60

permission sets for files and directories are set with what command

Back 60

chmod

- r read (4)

- w write (2)

- x execute (1)