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| == NMAP and SSH == | | == Statistics I604 == |
| | |
| | |
| '''NMAP'''
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| *Find my ip: ifconfig
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| *Scan networks: nmap <ip>
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| *Find live hosts: nmap -sP 192.168.0.*
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| *Scan specific port: nmap -p 80 server2.tecmint.com
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| *Scan a single ip address: nmap 192.168.1.1
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| *Scan a host name: nmap server1.cyberciti.biz
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| *Scan a host name with more info : nmap -v server1.cyberciti.biz
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| *Scan with disabled port scan: nmap -sn 192.168.2.1/24
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| *Read and scan from txt file: nmap -iL /tmp/test.txt
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| *Create the txt file to read from: cat > /tmp/test.txt
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| | |
| *Shut down a network: <sudo> shutdown -s -m \\192.168.1.1 or '''shutdown -h now'''
| |
| | |
| * nmap --iflist
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| | |
| '''SSH'''
| |
| *Connect: ssh collie.stanford.edu
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| *Log-in: ssh jhawkins@collie.stanford.edu
| |
| | |
| == Instruction sets ==
| |
| | |
| nstruction sets may be categorized by the maximum number of operands explicitly specified in instructions.
| |
| | |
| (In the examples that follow, a, b, and c are (direct or calculated) addresses referring to memory cells, while reg1 and so on refer to machine registers.)
| |
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| C = A+B
| |
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| * 0-operand (zero-address machines), so called stack machines: All arithmetic operations take place using the top one or two positions on
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| the stack: push a, push b, add, pop c.
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| C = A+B needs four instructions. For stack machines, the terms "0-operand" and "zero-address" apply to arithmetic instructions,
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| but not to all instructions, as 1-operand push and pop instructions are used to access memory.
| |
| | |
| *1-operand (one-address machines), so called accumulator machines, include early computers and many small microcontrollers: most instructions
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| specify a single right operand (that is, constant, a register, or a memory location), with the implicit accumulator as the left operand
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| (and the destination if there is one): load a, add b, store c.
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| C = A+B needs three instructions.
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| | |
| *2-operand — many CISC and RISC machines fall under this category:
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| CISC — move A to C; then add B to C.
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| C = A+B needs two instructions. This effectively 'stores' the result without an explicit store instruction.
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| CISC — Often machines are limited to one memory operand per instruction: load a,reg1; add b,reg1; store reg1,c;
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| This requires a load/store pair for any memory movement regardless of whether the add result is an augmentation
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| stored to a different place, as in C = A+B, or the same memory location: A = A+B.
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| C = A+B needs three instructions.
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| RISC — Requiring explicit memory loads, the instructions would be: load a,reg1; load b,reg2; add reg1,reg2; store reg2,c.
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| C = A+B needs four instructions.
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| | |
| *3-operand, allowing better reuse of data:[5]
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| CISC — It becomes either a single instruction: add a,b,c
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| C = A+B needs one instruction.
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| or more typically: move a,reg1; add reg1,b,c as most machines are limited to two memory operands.
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| C = A+B needs two instructions.
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| RISC — arithmetic instructions use registers only, so explicit 2-operand load/store instructions are needed:
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| load a,reg1; load b,reg2; add reg1+reg2->reg3; store reg3,c;
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| C = A+B needs four instructions.
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| Unlike 2-operand or 1-operand, this leaves all three values a, b, and c in registers available for further reuse.[5]
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| | | |
| LDA - Loads the contents of the memory address or integer into the accumulator
| | Primary Study Materials: |
| ADD - Adds the contents of the memory address or integer to the accumulator
| | '''Course Homepage:''' http://www.cs.ioc.ee/ITKStat |
| STO - Stores the contents of the accumulator into the addressed location
| | '''e-Book:''' http://onlinestatbook.com/Online_Statistics_Education.pdf |
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| ADD ;add one number to another number
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| SUB ;subtract one number to another number
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| INC ;increment a number by 1
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| DEC ;decrement a number by 1
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| MUL ;multiply numbers together
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| OR ;boolean algebra function
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| AND ;boolean algebra function
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| NOT ;boolean algebra function
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| XOR ;boolean algebra function
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| JNZ ;jump to another section of code if a number is not zero (used for loops and ifs)
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| JZ ;jump to another section of code if a number is zero (used for loops and ifs)
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| JMP ;jump to another section of code (used for loops and ifs)
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| 1 LDA #12 ;loads the number 12 into the accumulator
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| 2 MUL #2 ;multiplies the accumulator by 2 = 24
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| 3 SUB #6 ;take 6 away from the accumulator = 18
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| 4 JNZ 6 ;if the accumulator <> 0 then goto line 6
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| 5 SUB #5 ;take 5 away from the accumulator (this line isn't executed!)
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| 6 STO 34 ;saves the accumulator result (18) to the memory address 34
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| Addressing Mode Symbol Example Description
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| Memory Location LOAD 15 15 is treated as an address
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| Integer # LOAD #15 15 is treated as a number
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| Nothing HALT Some inst. dont need operands
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| | |
| == Truth Tables ==
| |
| | |
| '''Logical Conjunction(AND)'''
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| p q p ∧ q
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| T T T
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| T F F
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| F T F
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| F F F
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| | |
| '''Logical Disjunction(OR)'''
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| p q p ∨ q
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| T T T | |
| T F T
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| F T T
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| F F F
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| '''Logical NAND'''
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| p q p ↑ q
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| T T F
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| T F T
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| F T T
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| F F T
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| '''Logical NOR'''
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| p q p ↓ q
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| T T F
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| T F F
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| F T F
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| F F T
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| | |
| == Compression ==
| |
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| Data compression ratio is defined as the ratio between the uncompressed size and compressed size:
| |
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| Compression Ratio = Uncompressed Size / Compressed Size
| |
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| Thus a representation that compresses a 10MB file to 2MB has a compression ratio of 10/2 = 5, often notated as an explicit ratio, 5:1 (read "five" to "one"), or as an implicit ratio, 5/1. Note that this formulation applies equally for compression, where the uncompressed size is that of the original; and for decompression, where the uncompressed size is that of the reproduction.
| |
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| Sometimes the space savings is given instead, which is defined as the reduction in size relative to the uncompressed size:
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| Space Savings = 1 - Compressed Size / Uncompressed Size
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| Thus a representation that compresses a 10MB file to 2MB would yield a space savings of 1 - 2/10 = 0.8, often notated as a percentage, 80%.
| |
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| For signals of indefinite size, such as streaming audio and video, the compression ratio is defined in terms of uncompressed and compressed data rates instead of data sizes:
| |
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| Compression Ratio = Uncompressed Data Rate/ Compressed Data Rate
| |
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| and instead of space savings, one speaks of data-rate savings, which is defined as the data-rate reduction relative to the uncompressed data rate:
| |
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| Data Rate Savings = 1 - Compressed Data Rate / Uncompressed Data Rate
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| For example, uncompressed songs in CD format have a data rate of 16 bits/channel x 2 channels x 44.1 kHz ≅ 1.4 Mbit/s, whereas AAC files on an iPod are typically compressed to 128 kbit/s, yielding a compression ratio of 10.9, for a data-rate savings of 0.91, or 91%.
| |
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| When the uncompressed data rate is known, the compression ratio can be inferred from the compressed data rate.
| |
| | |
| == Bits and Bytes ==
| |
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| bit byte
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| bit 1 0.125
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| byte 8 1
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| Notes:The value of K (Kilo) during calculations can take two values 1024 or 1000, depends on which type of calculation you want to perform.
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| Consider using K = 1024 when you are considering storage capacity whether in hard disk, DVDs, flash drives or other devices and storage media.
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| K = 1000 should be used when you are thinking of throughput, ie the speed at which information is transferred.
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| Example: If your computer has 1 KB of disk space is says that he has 1024 B of space, now the throughput of your network card is 1 KB/s then
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| it is said that it transmits data to 1000 B/s. | |
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| Bit (b)
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| Byte (B)
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| Kilobit (Kb)
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| Kilobyte (KB)
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| Megabit (Mb)
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| Megabyte (MB)
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| Gigabit (Gb)
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| Gigabyte (GB)
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| '''Binary Equivalents'''
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| 1 Nybble (or nibble) = 4 bits
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| 1 Byte = 2 nybbles = 8 bits
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| 1 Kilobyte (KB) = 1024 bytes
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| 1 Megabyte (MB) = 1024 kilobytes = 1,048,576 bytes
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| 1 Gigabyte (GB) = 1024 megabytes = 1,073,741,824 bytes
| |
| | |
| '''Show addition of X and Y in binary'''
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|
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| 0 + 0 = 0
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| 0 + 1 = 1
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| 1 + 0 = 1
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| 1 + 1 = 0, and carry 1 to the next more significant bit
| |
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| '''Show subtraction of X and Y in binary'''
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| 0 - 0 = 0
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| 0 - 1 = 1, and borrow 1 from the next more significant bit
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| 1 - 0 = 1
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| 1 - 1 = 0
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| '''Show multiplication of X and Y in binary'''
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|
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| 0 x 0 = 0
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| 0 x 1 = 0
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| 1 x 0 = 0
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| 1 x 1 = 1, and no carry or borrow bits
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|
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|
| == Git ==
| | Primary Software: |
| | |
| The object database contains four types of objects:
| |
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| A blob (binary large object) is the content of a file. Blobs have no file name, time stamps, or other metadata.
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| A tree object is the equivalent of a directory. It contains a list of file names, each with some type bits and the name of a blob
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| or tree object that is that file, symbolic link, or directory's contents. This object describes a snapshot of the source tree.
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| A commit object links tree objects together into a history. It contains the name of a tree object (of the top-level source directory),
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| a time stamp, a log message, and the names of zero or more parent commit objects.
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| A tag object is a container that contains reference to another object and can hold additional meta-data related to another object.
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| Most commonly, it is used to store a digital signature of a commit object corresponding to a particular release of the data being tracked by Git.
| |
| | |
| '''heads'''
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| refers to an object locally.
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| '''remotes'''
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| refers to an object which exists in a remote repository.
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| '''stash'''
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| refers to an object not yet committed.
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| '''meta'''
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| e.g. a configuration in a bare repository, user rights. The refs/meta/config namespace was introduced resp gets
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| used by Gerrit (software)[clarification needed][45]
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| '''tags'''
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| see above.
| |
| | |
| '''Common Usage'''
| |
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| '''create a new repository'''
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| create a new directory, open it and perform a
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| git init
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| to create a new git repository.
| |
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| '''checkout a repository'''
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| create a working copy of a local repository by running the command
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| git clone /path/to/repository
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| when using a remote server, your command will be
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| git clone username@host:/path/to/repository
| |
| | |
| '''workflow'''
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| your local repository consists of three "trees" maintained by git. the first one is your Working Directory
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| which holds the actual files. the second one is the Index which acts as a staging area and finally the HEAD
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| which points to the last commit you've made.
| |
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| '''add & commit'''
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| You can propose changes (add it to the Index) using
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| git add <filename>
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| git add *
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| This is the first step in the basic git workflow. To actually commit these changes use
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| ''git commit -m "Commit message"''
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| Now the file is committed to the HEAD, but not in your remote repository yet.
| |
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| '''pushing changes''' | |
| Your changes are now in the HEAD of your local working copy. To send those changes to your
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| remote repository, execute
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| ''git push origin master''
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| Change master to whatever branch you want to push your changes to.
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| If you have not cloned an existing repository and want to connect your repository to a remote
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| server, you need to add it with
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| ''git remote add origin <server>''
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| Now you are able to push your changes to the selected remote server
| |
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| '''update & merge'''
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| to update your local repository to the newest commit, execute
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| ''git pull''
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| in your working directory to fetch and merge remote changes.
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| to merge another branch into your active branch (e.g. master), use
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| ''git merge <branch>''
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| in both cases git tries to auto-merge changes. Unfortunately, this is not always possible and results in conflicts.
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| You are responsible to merge those conflicts manually by editing the files shown by git. After changing, you need to mark them as merged with
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| ''git add <filename>''
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| before merging changes, you can also preview them by using
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| ''git diff <source_branch> <target_branch>''
| |
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| '''replace local changes'''
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| In case you did something wrong, which for sure never happens ;), you can replace local changes using the command
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| git checkout -- <filename>
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| this replaces the changes in your working tree with the last content in HEAD. Changes already added to the index,
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| as well as new files, will be kept.
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| If you instead want to drop all your local changes and commits, fetch the latest history from the server and point
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| your local master branch at it like this
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| git fetch origin
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| git reset --hard origin/master
| |
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| '''log'''
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| in its simplest form, you can study repository history using.. git log
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| You can add a lot of parameters to make the log look like what you want. To see only the commits of a certain author:
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| git log --author=bob
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| To see a very compressed log where each commit is one line:
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| git log --pretty=oneline
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| Or maybe you want to see an ASCII art tree of all the branches, decorated with the names of tags and branches:
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| git log --graph --oneline --decorate --all
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| See only which files have changed:
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| git log --name-status
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| These are just a few of the possible parameters you can use. For more, see git log --help
| |
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| '''tagging'''
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| it's recommended to create tags for software releases. this is a known concept, which also exists in SVN.
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| You can create a new tag named 1.0.0 by executing
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| git tag 1.0.0 1b2e1d63ff
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| the 1b2e1d63ff stands for the first 10 characters of the commit id you want to reference with your tag.
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| You can get the commit id by looking at the...
| |
| | |
| == Decimal <--> Hexadecimal ==
| |
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| Hexadecimal Decimal
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| 0 0
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| 1 1
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| 2 2
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| 3 3
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| 4 4
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| 5 5
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| 6 6
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| 7 7
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| 8 8
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| 9 9
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| A 10
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| B 11
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| C 12
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| D 13
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| E 14
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| F 15
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| Radio station is streaming MP3 audio at 192kbps. How many 500GB harddisks are required in order to archive 8 years of shows?
| |
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| 192 kbps = 192 000 bps
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| 1 536 000 Bps
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| 1500 Kb/s
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| 1.46484375 MB/s
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| 8 years = 2920 days = 70080 hours = 4204800 minutes = 252288000 seconds
| |
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| 172 228608 MB
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| 16 8192 GB
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| 336.384 500GB harddrives
| |
| | |
| == Audio and Images ==
| |
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| '''Audio'''
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| In digital audio, 44,100 Hz (alternately represented as 44.1 kHz) is a common sampling frequency.
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| Analog audio is recorded by sampling it 44,100 times per second, and then these samples are used
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| to reconstruct the audio signal when playing it back.
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| | |
| '''Images'''
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| '''PNG''' supports palette-based images (with palettes of 24-bit RGB or 32-bit RGBA colors), grayscale images (with or without alpha channel),
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| and full-color non-palette-based RGB[A] images (with or without alpha channel). PNG was designed for transferring images on the Internet,
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| not for professional-quality print graphics, and therefore does not support non-RGB color spaces such as CMYK.
| |
| | |
| '''JPEG'''/JFIF supports a maximum image size of 65,535×65,535 pixels, hence up to 4 gigapixels (for an aspect ratio of 1:1).
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| JPEG is a commonly used method of lossy compression for digital images, particularly for those images
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| produced by digital photography. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size
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| and image quality. JPEG typically achieves 10:1 compression with little perceptible loss in image quality.
| |
| | |
| ----
| |
| | |
| '''Compact Disc'''
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| Capacity Typically up to 700 MiB (up to 80 minutes audio)
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| Read mechanism 780 nm wavelength (infrared and red edge) semiconductor laser, 1200 Kibit/s (1×)
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| Write mechanism 1200 Kibit/s (1×)
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| | |
| Sampling 4 bit audio (2^4) gives us only 16 values, a far cry from 16-bit audio's 65,536! sample rate.
| |
| '''Sample rate''' refers to the number of samples or measurements taken each second from a recording.
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| The typical CD sample rate is 44.1kHz, or 44,100 samples per second.
| |
| | |
| The '''bit rate''' is quantified using the bits per second unit bit/s, often in conjunction with an SI prefix such as "kilo"
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| (1 kbit/s = 1000 bit/s), "mega" (1 Mbit/s = 1000 kbit/s), "giga" (1 Gbit/s = 1000 Mbit/s) or "tera" (1 Tbit/s = 1000 Gbit/s).
| |
| The non-standard abbreviation "bps" is often used to replace the standard symbol "bit/s", so that, for example, "1 Mbps" is
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| used to mean one million bits per second.
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| One byte per second (1 B/s) corresponds to 8 bit/s.
| |
| | |
| The '''RGB565 color format''' is the same as the RGB555 color format, except that 6 bits are used for
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| the green value instead of 5. Therefore, all 16 bits are in use. The organization of the pixels
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| in the image buffer is from left to right and bottom up.
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| '''RGB888''' --> 24-bit RGB (888)
| |
| | |
| == Statistics Lecture One, 02.01.16 ==
| |
| '''Primary Material:'''
| |
| '''Course Homepage:''' http://www.cs.ioc.ee/ITKStat
| |
| '''e-Book:''' http://onlinestatbook.com/Online_Statistics_Education.pdf
| |
| '''
| |
| '''Primary Software'''
| |
| '''R:''' https://www.r-project.org/ | | '''R:''' https://www.r-project.org/ |
|
| |
|
| '''Introduction to Statistics'''
| | == Python I703 == |
| '''Descriptive''' statistics are used for presenting, organizing and summarizing data.
| |
| '''Inferential''' statistics are about drawing conclusions about a population based on data observed in a sample.
| |
| | |
| '''Data Analysis Process'''
| |
| '''Data collection and preparation:''' Collect Data, prepare codebook, set up structure of data, enter data, screen data for errors
| |
| '''Exploration of data:''' Descriptive statistics, graphs
| |
| '''Analysis:''' Explore relationship between variables, compare groups
| |
|
| |
|
| == Python Lecture and Practicum Notes ==
| |
|
| |
|
| '''Lecture 1'''
| | Get an idea what to do by next week. Ideas: |
| ---------------
| | '''1. Pyglet,pygame or kivy for a game or simulation:''' |
| | |
| Get an idea what to do by next week. Ideas: | |
| // '''1. Pyglet,pygame or kivy for a game or simulation:'''
| |
| 1.1. MP beat em' up | | 1.1. MP beat em' up |
| 1.2. Survival space sim, use webcam for dynamic view | | 1.2. Survival space sim, use webcam for dynamic view |
| Line 404: |
Line 21: |
| http://learnpythonthehardway.org/ | | http://learnpythonthehardway.org/ |
|
| |
|
| // '''2. WebApp'''
| | '''2. WebApp''' |
| 2.1. Budget Management with a GUI | | 2.1. Budget Management with a GUI |
|
| |
|
| // '''Notes:'''
| | '''Notes:''' |
| * Set up RPi web-server | | * Set up RPi web-server |
| * Use '''XMind''' to map the idea first | | * Use '''XMind''' to map the idea first |
| Line 415: |
Line 32: |
| * Check out Notepad++ | | * Check out Notepad++ |
|
| |
|
| == Web App Programming Lecture and Practicum Notes == | | == Web Application Programming I702 == |
| database: MySQL -- hosts data, indexed | | |
| php: Generates html, server side language | | '''node.js''' |
| Apache: reads php files and over excecution to PHP interpreter | | '''ngix''' |
| html: Structure and contents of the web page, (dom-tree) | | '''nchan''' |
| css: styling information
| | |
| javascript: client side programming, interacts with html
| | '''Useful links:''' |
| ubuntu: hosts the programs ( packetization, tcp segmentation ) | | http://enos.itcollege.ee/phpmyadmin/ |
| | http://enos.itcollege.ee/~ksaareme |
| | |
| | '''W3C validation:''' https://validator.w3.org/ |
| | |
| | == Node.js == |
|
| |
|
| HTTP requests
| | Stuff about node.js. |
| '''node.js -- php'''
| | |
| '''ngix -- apache'''
| | == Operating Systems == |
| '''nchan'''
| | |
| | Command line: |
|
| |
|
| http sockets, streaming push module
| | '''Options modify the behavior of commands:''' |
| WAMP for Windows
| | ls -a lists all contents of a directory, including hidden files and directories |
| | ls -l lists all contents in long format |
| | ls -t orders files and directories by the time they were last modified |
| | Multiple options can be used together, like ls -alt |
| | '''From the command line, you can also copy, move, and remove files and directories:''' |
| | cp copies files |
| | mv moves and renames files |
| | rm removes files |
| | rm -r removes directories |
| | '''Wildcards are useful for selecting groups of files and directories''' |
|
| |
|
| http://enos.itcollege.ee/phpmyadmin/
| |
| PHP and APACHE is there
| |
|
| |
|
| http://enos.itcollege.ee/~ksaareme to see changes
| |
|
| |
|
| '''W3C validation''' https://validator.w3.org/
| | '''Redirection reroutes standard input, standard output, and standard error.''' |
|
| |
|
| == Node.js ==
| | '''The common redirection commands are:''' |
| | > redirects standard output of a command to a file, overwriting previous content. |
| | >> redirects standard output of a command to a file, appending new content to old content. |
| | < redirects standard input to a command. |
| | | redirects standard output of a command to another command. |
|
| |
|
| Stuff about node.js.
| | '''A number of other commands are powerful when combined with redirection commands:''' |
| | sort: sorts lines of text alphabetically. |
| | uniq: filters duplicate, adjacent lines of text. |
| | grep: searches for a text pattern and outputs it. |
| | sed : searches for a text pattern, modifies it, and outputs it. |
