Linux

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The Terminal

[username@machinename ~] $

~ denotes user's home directory
$ denotes normal user
# denotes superuser
[\u@\h \W]\$
Ctrl+Alt+t = open terminal within the GUI
Ctrl+Alt+F1 through Ctrl+Alt+F6 = Access the virtual terminals from desktop
Atl+F1 through Alt+F7 = switch between virtual terminals Alt+F8 = return to GUI
Ctrl+c = Kill process in terminal (INT), Ctrl+z = Suspend process in terminal (TSTP)
Tab = Completion
Ctrl+l = Clear screen
Ctrl+u = Clear prompt
Start process in background: processName &
Disregard $PATH, search current directory: ./processName
cAsE sEnSiTiVe...

Do not use spaces in folder and file names -- Linux does not like that at the command line!

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Wildcards * ?

* any characters
? any character
[characters] Any character that is a member of the set [characters]
[!characters] Any character that is not a member of set [characters]
[[:class:]] Any chracter tht is a member of the class

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Bash (Bourne Again SHell) / Terminal Commands

A

alias Create an alias: alias [-p] [name[=value] ...]

alias quit='exit'
alias -p
*Do NOT try to alias cls - wont work
*Do NOT alias cl - there is a linux prog by that name

apropos, man -k Search manual for appropriate command

aspell Spell Checker: aspell check myfile.txt

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B

bg Send process to background using jobspec: bg %jobspec

To start process in background type: processName &

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C

cal Calendar

cat Concatenate and display the content of files: cat [-Ans...] [File]...

cat movie.mpeg* > movie.mpeg
cat > myFile.txt
Ctrl+d to quit

cd Change directory: cd [options] [directory]

cd Change to home directory
cd - Change to the previous working directory
cd ~username Change to home directory of username

chgrp Change group ownership: chown [options]... :group file...

chmod Change access permissions

Octal: chmod 644 myFile.txt

sticky bit 1000

setgid bit 2000

setuid bit 4000

Symbolic: chmod u+rw,go-x myFile.txt

u User, g Group, o Others, a All

+, -, =

r, w, x, s setuid or setgid, t sticky bit

chown Change file owner and group: chown [owner] [:group] file...

clear Clear terminal screen

comm Compare two sorted files

comm -12 file1.txt file2.txt
comm --nocheck-order months.txt months2.txt

cp Copy: cp [-airuv]... [source] [destination]

cut Divide a file into several parts: cut [-c -d: -f]... [FILE]...

cut -d: -f5 /etc/passwd | cut -c 2-5 > foo.txt

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D

date Display/change date/time: date [option]... [format]

df Display free disk space: df [option]... [file]...

diff Display the differences between two files: diff [-c -i -u] FILES

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E

echo Display message on screen: echo [-e]... [string]...

echo front-{A,B,C}-back
echo Number_{1..7}
echo {Z..A}
echo $((2+4))
echo $USER

expand Convert tabs to spaces

exit Exit from program, shell or log out of network: exit

export Set environmental variable

export PS1

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F

fg Send process to foreground specifying jobspec

file Determine file type: file

find Search for files that meet a desired criteria

find ~ -type f -name "*.jpg" -size +1M -print | xargs ls -l
find ~ -type f -name "*.jpg" -size +1M -delete
find ~ -type f -name "*.jpg" -size +1M -exec rm '{}' ';'
find ~ $-type f -not -perm0600$ -or $-type d -not -perm 0700$
find . -regex '.*[^-_./0-9a-zA-Z].*'

free Display memory usage: free [-b|-k|-m|-g|-h]

ftp File Transfer Protocol: ftp myFileServer

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G

grep Search files for specific text: grep [-cEhivlLn...] regex [file...]

ls /bin | sort | uniq | grep ntfs
grep myText myFile.txt
grep -h '[^bg]zip dirlist*.txt
grep '^Anchor[^nothese]' ships.txt
grep -h '^[A-Z]' capitol.txt
grep -i '^..j.r$' usr/share/dict/words
echo "(555)123-4567" | grep -E '^$?[0-9]{3}$? [0-9]{3}-[0-9]{4}$'

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H

hash Remember the full pathname of a name argument: hash [-r] [-p filename] [name]

head Output the first part of files: head [options]... [file]...

head -5 myFile.txt

help Help for shell builtins

history Command History: history -c

hostname Print or set system name

sudo hostname my-new-computer-name Change computer name temporarily
Modifiy /etc/hostname with a text editor to change name permanently

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I

id Print user and group id's: id [options]... [username]

info Manual in info format: info [command]

? = command help
n = next node
p = prev node
u = parent node
ENTER = follow hyperlink
q = quit

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J

jobs List active jobs

join Join lines on a common (sorted) field as in a relational DB

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K

kill Kill a process by specifying PID or %jobspec

killall Kill multiple processes by name

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L

less Display output one screen at a time: less [options]

G = move to end
1G or g = move to begining
/char = search for char
n = next occurence of prev search
h = help
q = quit

let Perform arithmetic on shell variables

ln Create a link to a file: ln [-s]...

*a hard link cannot reference a directory or a file outside its own filesystem

locate Find files (updatedb = update locate database)

ls List files: ls [-aFhilrS | -t]... [.. | ~ | /etc]...

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M

man Manual: man [option]... [section] [command]

user commands
interfaces for kernel
interfaces to C library
device nodes and drivers
file formats
games
misc.
admin

mkdir Create new directory: mkdir [-p]... [directory]...

mkdir -p playground/myDir-{00{1..9},0{10..99},100}

more Display output one screen at a time, forward only

mv Move or rename files or directories: mv [iuv]... [source] [destination]

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N

netstat Networking information: netstat -r; netstat -ie ~ ifconfig

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O

P

passwd Modify a user password

paste Merge lines of files: paste [-d:]... [file]...

ping Test a network connection: ping -c5

printenv Print environment variables

printf Format and print data

printf %'x\n' "$((2#10001100))"

ps Process status (gives PID)

pwd Print Working Directory: pwd [option]...

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Q

R

read Read a line from standard input: read -p "Press enter to continue"

rm Remove files: rm [-irfv]... [file]

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S

scp Secure copy (remote file copy)

set View all variables, set shell variables and functions

set PATH="/bin:/usr/bin:/usr/sbin:usr/local/bin"

sftp Secure File Transfer Program

shutdown Shutdown or restart linux

shutdown -P now "Bye"

sleep Delay for a specified time

sort Sort text files: sort [options] [file...]

sort -t: -k7 /etc/passwd | head
sort -k1,1 -k3.7bnr -k3.1bnr -k3.4bnr distros.txt | tee sortAZandDate.txt

source Run commands from file: source filename [arguments]

source .bashrc (same as . .bashrc)

ssh Secure Shell client (remote login program)

stat Display file or file system status

su Substitute user identity: su[-l|-p] [user] or su -c 'command'

sudo Execute command as superuser or another user: sudo [command]...

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T

tail Output the last part of files: tail [options]... [file]...

tail -n 5 myFile.txt

tee Redirect output to multiple files: tee [options]... [file]...

ls /usr/bin | tee myFile.txt | grep zip

top List processes running on the system

touch Change file timestamps / create file: touch [options]... File...

playground/myDir-{00{1..9},0{10..99},100}/myFile-{A..Z}

tr Translilterate, squeeze, delete characters

cat lowercasefile | tr a-z A-Z > uppercase.txt
tr -d "\r" <dos.txt> unix.txt
tr -s "o" <doubleoofile.txt> singleo.txt
ROT13: echo "secret text" | tr a-zA-Z n-za-mN-ZA-M

traceroute tracepath, Trace Route to Host

tree list directories in tree format: tree -aCdL 1

type Identify command type: type [-atp] [name ...]

Executable
Shell builtin
Shell function
Alais

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U

unalias Remove an alias: unalias [-a] [name ... ]

umask Users file creation mask

uniq Report or filter out repeated lines in a file: uniq [-c -d -i -fn -sn -u]... [InputFile [OutputFile]]

sort foo.txt foo2.txt | uniq > finalfoo.txt

unset Remove variable or function names: unset [-fv] [name]

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V

W

wc Print byte, word, and line counts: wc [-c|-i|-l|-w]... [file]...

wget Retrieve web pages or files via HTTP, HTTPS or FTP

which Display users path to a command: which [options] [--] program_name [...]

whatis Display brief description of command: whatis [command]...

who List all usernames currently logged in: who [options] [file] [am i]

whoami Display the current user id and name: whoami [options]

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X

xargs Execute command, passing constructed argument list(s): xargs [options] [command]

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Linux File System

     /bin - binaries essential to boot system and run
     /boot
        /grub/grub.conf or menu.lst        
        /RAM disk, boot loader
        /vmlinuz (kernel)
     /dev - device files for system
           (block and charactor type)
     /etc - configuration files for system        
        /passwd, group, rc, group, crontab
        /rc.d/rc.sysinit
        /bash/bash.rc                        
        /profile
        /fstab - devices mounted at boot
     /home
        /.bash_profile
        /.bash_login
        /.bashrc
        /.profile
     /lib - libraries, support for symbolic linking
     /lost+found - for filesystem recovery
     /media - temporary mount points (newer systems)
     /mnt - temporary mount points (older systems)
     /root - home directory for root (super user)
     /tmp

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File Type

- Regular file
d Directory
l Symbolic link
c Character special file
b Block special file

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File Mode

Mode	File	Directory
r	open/read	list contents (x must be set also)
w	write	create/delete/rename contents (x must be set also)
x	execute	enter

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Redirecting stdin(0), stdout(1) and stderr(2)

<, > and >> (redirectors)
> Redirect stdout from a command to a file
>> Redirect and append stdout to file
2> Redirect stderr from a command to a file
2> /dev/null Send stderr to bit bucket
< Redirect stdin: cat -n < myFile.txt
Redirect stdout and stderr to one file: ls -l > list.txt 2&>1 or ls -l &> list.txt

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Pipe, tee

Pipe (filter) one command into another: ls /bin /usr/bin | sort | uniq -d | less
tee: Send output to a file as well as the terminal eg: ls /usr/bin | tee myFile.txt

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Escape Characters

\a Bell
\b Backspace
\n Newline
\r Return carriage
\t Tab

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Arithmetic and Base Expansion

echo $((2+2))4
echo $(($((5**2)) * 3))
echo five divided by 2 equals 2 $((5/2))
echo FromA-{A,B,C}-ToC
echo Number{1..5}
echo {Z..A}
mkdir {2005..2015}-0{1..9} {2009..2015}-{10..12}
echo $(ls -l | wc -l)

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Regular Expression Metacharacters ^ $ . ? * + - | [ ] { } ( ) \

^ $ Anchors
. any element
? match element zero or one time
* match element zero or more times
+ match element one or more times
-
| OR
^ NOT when inside [ ]
[ ]
{ }

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POSIX Character Classes

[:alnum:] Alphanumeric character
[:alpha:] Alphabetic character
[:digit] Numeral
[:lower:] Lowercase letter
[:upper:] Uppercase letter

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Text Editors

vi editor

vi myFile = open/create myFile
h, j, k, l = move
w = forward one word
b = back one word
nG = goto line n
Ctrl+f = forward a screen
Ctrl+b = back a screen
Ctrl+u = up half screen
Ctrl+d =down half screen
i = Insert mode
(Esc = return to Command mode)
a = append after cursor A = append at line end
o = start new line below O = start above
r = replace character R = replace till Esc
nyy = copy n lines (including current)
ndd = cut n lines
p = paste
x = delete
dw = delete to end of word
D = delete to end of line
u = undo
Ctrl+r = redo
~n = change case of n characters
:q = quit :q! = quit w/o saving
:w [filename] = save [as]
:wq = save and quit
:x = save and quit
:e filename = save, quit and open filename
:r = redo
:s/old/new/g = replace all on line
:%s/old/new/g = start at beginning of file
:! command = run linux command
:set showmode

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vim

vi iMproved - a programmers text editor.

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Nano

Nano's ANOther editor, an enhanced free Pico clone.

nano myFile= open/create myFile
ctrl+o Enter = save
ctrl+x = exit

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Emacs

Text editor that is really an IDE

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Pico

Pico (Pine composer) is a text editor for Unix and Unix-based computer systems

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Scripts

Script must start with the shebang:

#!/bin/bash
# begins a comment if it isn't the shebang

Script must be executable:

chmod 700, chmod 770 or chmod 777

Script must be on the path:

~/bin or /usr/local/bin or /usr/local/sbin
PATH=$PATH:. = adds current location to path
. .bashrc = sources the bashrc file
Do NOT name script "test" - linux don't like it (test.sc will work tho)

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If...Then...Else


    echo –n “Who is your favorite instructor? “
    read INST
    if [ “$INST” = “Killham” ]
    then
        echo “Good choice, you get an A!”
    else
        echo “ Would you like to rethink your answer?”

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For Loop


    for name in Karen Jo Barb Linda Laurie Kim
    do
        echo “Welcome $name”
    done

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While Loop


    echo –n “Try to guess my favorite instructor “
    read guess
    while [ “$guess” != “Schuster” ]; do
    echo “No, not that one. Try again. “;
    read guess
    done

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Example Script


    #!/bin/bash
    clear
    #echo -n "Enter name of file to create: "    
    #read myString
    read -p "Enter name of file to create: " myString
    touch $myString
    free > $myString
    echo >> $myString
    df >> $myString
    echo >> $myString
    echo "Results from ping -c 3 www.unl.edu"  >> $myString
    ping -c 3 www.unl.edu >> $dateFile

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Installations and Updates

sudo apt-get install
sudo yum install
sudo apt-get update
sudo apt-get upgrade
sudo apt-get remove
sudo apt-get purge

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Tarball

sudo tar -cvpzf [Create Verbose PreservePermissions z=compress Filename] backup.tar.gz --exclude=/mnt /directoryToBeBackedUp

sudo tar -xvpzf [eXtract Verbose PreservePermissions z=uncompress File] backup.tar.gz -C /recoveryDirector [ChangeDirectory]

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Cron Job


    sudo crontab -e & choose text editor
    m h dom m dow comm
    Min 0-59
    Hour 0-23
    DayOfMonth 1-31
    Month 1-12
    DayOfWeek 0-6 (Sun to Sat)

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Administration


    su = change ID or become Super User
    sudo = Super User Do
    gksudo = for apps using a GUI
    visudo = edits sudoers file
    sudo adduser napes
    sudo userdel napes
    sudo passwd = change password
    sudo vi /etc/passwd = etc/passwd contains user names, home directories...
    sudo groupadd napesGroup
    sudo groupdel napesGroup
    sudo adduser napes napesGroup
    sudo deluser napes napesGroup
    sudo vi /etc/group
    chmod 777 example.txt = gives Read, Write & eXecute permissions to user, group and others to file example.txt eg. 111 111 111

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System


    sudo apt-get install
    ubuntu-restricted-extras
    echo $SHELL = Shell you are using
    BASH (Bourne-Again SHell) freeware, most common, Brian Fox and Chet Ramey.
    CSH (C SHell) The C shell's syntax and usage are very similar to the C programming language.
    KSH (Korn SHell) David Korn	AT & T Bell Labs.
    TCSH enhanced, compatible version of the Berkeley UNIX C shell (CSH).
    ps = report a snapshot of the current process
    es
    pa aux = List all processes in detail running on the system
    uname = get name and information about current kernel
    version = kernel info
    df -h = report file system disk space usage
    df -i
    du -cksh = size of current folder
    du -cksh file.examp = size of file.examp
    sudo du -s -h -x /* = estimate file space usage
    sudo top  (+ h) = "task manager"
    ipcs -m = provide info on ipc facilities
    inxi -xG =
    sleep
    kill PID
    killall
    processName
    xkill = starts GUI for killing windows
    cd /boot/grub/
    vi menu.lst

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Formatting Floppy Disk


    $ dd bs=512 count=2880 if=/dev/zero of=floppy.img
    $ mkfs.msdos floppy.img
    $ sudo mount -o loop image.img /media/floppy/
    <<<copy your files on to the "drive" now>>>
    $ sudo umount /media/floppy/

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Networking


    whois
    netstat -print network connections, routing tables, interface...
    sudo ifconfig
    sudo dhclient = release/renew ip address
    sudo vi /etc/resolv.conf
    sudo vi/etc/network/interfaces
    sudo /bin/hostname (or just hostname)
    sudo /bin/hostname name = renames computer to "name"
    sudo /etc/init.d/exampleService stop
    sudo /etc/init.d/exampleService start
    sudo /etc/init.d/exampleService restart
    sudo service networking restart
    sudo vim /etc/vsftpd.conf
    sudo service vsftpd restart

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WireShark


    sudo apt-get install wireshark libcap2-bin
    sudo groupadd wireshark
    sudo adduser napes wireshark
    sudo chgrp wireshark /usr/bin/dumpcap
    sudo chmod 755 /usr/bin/dumpcap
    sudo setcap cap_net_raw,cap_net_admin=eip /usr/bin/dumpcap

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Firewall


    sudo apt-get install gufw
    turn on
    add rules (show extended options) + :
    select number 0, deny, service, SSH
        or
    sudo ufw
    status verbose
    sudo ufw allow/deny x.x.x.x
    sudo ufw allow/deny [port#]

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Linux Mint

Unable to Mount Floppy Error [solved]:

sudo mateconf-editor apps\caja\preferences\media_automount (uncheck),

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Decryption Prompt Not Appearing [solved]:

sudo vi /etc/default/grub

Add this line

GRUB_GFXPAYLOAD_LINUX=text

sudo update-grub

sudo reboot

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Kernel Won't Update - Drive Full [solved]:

Separate partition for /boot seems to for LVM and/or "full" disk encryption on the rest of the drive.

The likely cause of this issue is too many previous kernels installed. The /boot directory contains all of the kernel images. The separate partition for /boot is only around 227MB in size. This partition is full. Ubuntu issues kernel updates which bump the version number in the package name fairly frequently even for long term stable versions, so over time if you keep the system up to date, the /boot directory will grow.

Find the currently running kernel with:

uname -r

List all installed kernels with:

aptitude search ~ilinux-image

This may also return some packages that aren't kernels. There is usually no need for more than two kernels to be installed - the kernel in use and, as a fallback, its predecessor.

Remove older kernels, one by one, like this:

sudo apt-get autoremove linux-image-3.2.0-23-generic

Substitute "3.2.0-23-generic" with the actual kernel version you want to remove! Don't remove packages such as linux-image-generic! Do not to remove the currently running kernel!

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NVIDIA

sudo apt-get install nvidia-current-updates

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Commandes Dispo (TI-89 Titanium)

Voici la liste des commandes disponibles pour le kernel (dans le terminal):


    cd
    chroot - change root directory?
    copy
    cp
    echo
    getfold
    hostname
    hwclock - query or set the hardware clock (RTC)
    logname
    ls
    mcd
    mdel
    mkdir
    mmd
    mrd
    netstat
    rm
    rmdir
    rusers
    sleep
    uname
    version
    who

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