Lab46 Wiki

wc -w displays the number of files (word count)

ls -d prevents ls form looking into another directory

a process is a program in action

pid 2^16 =65536

starts @ 1

as long as there are pid to allocate everything will work fine

ps - shows processes

kill -1 PID hangs process

kill -2 PID interrupts process

ps aux | grep $USER

AT&T sh - bourne shell

bash - bourne again shell

Wild cards

wild cards operate on command line

? matches any single character

* match 0 or more characters

ls ????

[] match any character inside

ls l* (match any beginning with l)

ls *.zip (match any with .zip)

[^] do not match anything inside

ls *.tar* (match anything with .tar)

ls ?[aeiou]? match any characters with any lower case vowel inside

DATA PROC

USE: wc, head, tail, grep, cut, |, sort, cat

tr -translate, squeezes, and or deletes characters from std-in writing to std-out

ascii man page man 7 ascii

ps shows PID

spawning / forking processes

when a process creates another process

there is no limit to processes on if one is put in place by administrator

only the hardware and software limit the number of processes otherwise

ulimit - look up the amount of resources you can or cannot use

getent passwd - shows

getent passwd | cut -d ’:’ -f1,7 | head -n 75

Quotes:

* ‘ - full quote = literal quote
* “ - half quote = allow for expansion (variable)
* ` - back-quote = command expansion

$__ this is how the shell (bash) denotes a environment variable

$ means access

Unix pipe | takes std-out and places into std-input

cat short for concatenate

bc -l is for the calculator

cp /etc/motd ~

absolute path for home dir

(~ signify's home dir)

Cat - looking at files ASCII 8 -bit code

Cat -n - shows line #

Cat -e - puts $ at the end of lines

Tries to show all files as one of 256 symbols

white space characters

• tab
• space
• backspace

: extended command mode

Ctrl - S locks the terminal Ctrl - Q unlocks the terminal

$ means end of line

od /

octodump of the file

od -x for hex dump

grep

globally search regular expression print

grep ‘the’

looks for the expression the in the give files

grep ‘\<the\>’ /

looks for just the word the

grep -i ‘’

- looks for upper and lowercase version of given variable

grep -o ‘’

- just shows the matching text

grep -n ‘’

- displays line #

Pipe | - takes the output and send it to the input of another command

Pipe anything that send to std out like

ls/who

od -x /ect/motd | grep -o '0a' |wc -l

endianess

little endian : lower order

big endian: higher order

network communication is big endian

intel machines use little endian

tail used to see the end of a file

tail -f can see all changes as they are taking place

cat allows you to see the contents of a file on the std out (the screen)

nearly any file can be inputted or outputted from std-out

Symbolic link - file that points to another file

object file executable - binary file

set vid -gives root access set gid -assign group privileges

bin - located in \bin contains most normal user commands

sbin \sbin administrator commands

submitting projects from wiki

$ submit unix “nameofproject” “webaddress(fullwebaddress)”

should say submitting unix project “name”

“web address”

successfully submitted

i = insert I = insert at the end

a = append A = append at the end

VIM is improved version of VI,

HJKL are = to arrow keys

W = skips words

4W = skips 4 words and so on

B is back

$ goes to the end of the line

3G, goes the third line

X is delete, x is backspace

dw, db, dW, dB - delete by word

d^, d$, dd

p is paste

S - substitute

cw cb cW cB - change word

c^, c$

o = insert new line below

O = insert new line above cursor

y = yank

yw = yanks into a buffer

/”char” brings the cursor to the word

n goes to next, N goes back

:w “filename” saves files

:w if you already put filename when starting Vi

“filename”

:q exit VI

no saving just exit :q!

status unix

this command will show attendance, opus and project status

cal will give you the current month & day

cal 2014

will give you the yearly calendar

cal 04 2014

will show a specific month calendar

date by default will give you the day month time time:zone year TUE SEP 9 16:30:30 EDT 2014

you can reformat the date string

date -d 2014 08 03 “j”

%J will give date of the current month

%s will give you the amount of time since the beginning of time

1970-01-01 00:00:00 utc

pom - phase of moon will display the moon phases

man - for manual page or pages

write - to write to another user

talk - works like instant message

/ect directory contains many system config files

shadow - is where encrypted passwords would be saved if on a stand alone system

the motd resides within /ect

cat motd shows you the banner

/lid - system libraries reside here

ldd will show shared library dependencies

everything is organized in both unix and linux

/media - common mount points

/proc -process infromation psendo-filesystem

will show process id's

each sub dir is a process id

/sbin -system binaries

/tmp - were temporary data is stored

permissions are drwx rwx rwx user group global

/van collection of everything, not really any specific

/usr compiler is located here

/usr /bin tools in here

/usr /lib supporting libraries

everything is underneath one file system

even if something is mounted

pwd shows current directory

cd allows for changing of directories

cd . current dir navigation

cd .. relative path, takes to parent dir

absolute path is a specific address that works from any location

universally specific

echo - simple print statement that will come out the std out

(> redirects std out to file “writes”)

(» redirects std out to file “appends”)

2> redirects std err “writes”

2» “ ” appends

Unix Philosophy

• Small is beautiful
• Do one thing and do that one thing well
• Everything is a file

3 types of files

• Regular/ ordinary
• directories(links)(metadata)
• Special- Manifestation of hardware ie(keyboard,screen mouse…etc…)

3 tiers of ownership

user group other(world/global)

dwrx wrx wrx d for dir Special = B, C, P, S

R- read 4 in octal W- write 2 in octal x- execute 1 in octal - no permission 0 in octal

Permissions uses octal # system to give permissions

there is no un-delete option- only the superuser has this option however, this does not protect this file from being over written If the data is over-written in the swap file system then the file/ data cannot be retrieved

My user name: ddewert1

pass:dy**

to remote on to lab 46 ssh ddewert1@lab46.corning-cc.edu

to detach from the server

ctrl + a + d

for class chat

irssi

/server irc /join unix /join lab46

common commands

who - shows who is on the system at that instant

ls -l list dir's and or files in current dir

pwd

alpine for email

lab46:~$ this is your user home dir

there are 2 regular states

regular and superuser

:~/src$ — directoy

This is a sample format for a dated entry. Please substitute the actual date for “Month Day, Year”, and duplicate the level 4 heading to make additional entries.

As an aid, feel free to use the following questions to help you generate content for your entries:

• What action or concept of significance, as related to the course, did you experience on this date?
• Why was this significant?
• What concepts are you dealing with that may not make perfect sense?
• What challenges are you facing with respect to the course?