Dump
Dump ( English : [ dʌmp ] [also] for [the] unloading or tipping and transfer [also] for depot , unloading area or warehouse ) or memory dump refers to a copy or extract of a memory content in data processing . The memory dump can be output on the monitor , printer or as a file ; the content can be displayed in character format , hexadecimal , binary or octal , for example. A dump ( English crash dump ) is mostly used to diagnose errors in the event of a program crash or to analyze the performance .
species
If it concerns the contents of the registers of a processor , one speaks of register dump , it concerns the contents of the main memory , of memory dump . Extracts from a database are called database dumps , the image or section of a file is called file dump. They serve as data backup or can be used for migration .
Core dump
Under almost all operating systems, memory dumps are automatically created after serious errors have occurred or can be created specifically by programmed calls.
Under Linux and Unix , for example, the so-called coredump is created after a crash ; the memory of the crashed process is written to a file and can later be analyzed with a debugger . The name core dump is derived from the core memory (English core memory ) from, an early form of main memory in computer systems. These memory dumps of the register and main memory image of a process are also called post-mortem dumps, from the Latin post mortem (German "after death").
With Microsoft operating systems, the Windows system service Dr. Watson creates a dump with the file extension .dmp after a crash.
File system dump
Under Linux or Unix there are programs like dump and dd with which u. a. entire file systems or the contents of block devices can be backed up (or overwritten) with high data throughput.
Hexdump
Hexdump refers to the representation of computer data in the hexadecimal number system (in which four bits can be combined per digit). If you want to analyze data (in RAM or in files) close to the system, a hexadecimal representation is often essential.
Example:
Under DOS you can get hex dumps with the DEBUG command, under CP / M with dump .
Unix systems provide commands such as "hexdump" for creating a hexdump, which often contain additional output options (decimal representation, text representation). A dump can also be created with "od -x" ( o ctal d ump).
The following example shows the hex dump of a text file in ASCII code. On the left is a (hexadecimal) position information (address) in the file, in the middle the characters are given in their hexadecimal representation (16 characters, in two groups of 8 characters each) and on the right as text, whereby memory contents that do not represent a character that can be displayed shown as “.”.
00000000 48 69 65 72 20 69 73 74 20 65 69 6e 20 42 65 69 |Hier ist ein Bei| 00000010 73 70 69 65 6c 74 65 78 74 2e 20 44 65 72 20 48 |spieltext. Der H| 00000020 65 78 64 75 6d 70 20 69 73 74 20 61 75 66 20 64 |exdump ist auf d| 00000030 65 72 20 6c 69 6e 6b 65 6e 20 53 65 69 74 65 20 |er linken Seite | 00000040 7a 75 20 73 65 68 65 6e 2e 0a 0a 4e 65 75 65 20 |zu sehen...Neue | 00000050 5a 65 69 6c 65 6e 20 6f 64 65 72 20 41 62 73 e4 |Zeilen oder Absä| 00000060 74 7a 65 20 73 69 6e 64 20 64 61 6e 6e 20 61 75 |tze sind dann au| 00000070 63 68 20 22 5a 65 69 63 68 65 6e 22 20 6d 69 74 |ch "Zeichen" mit| 00000080 20 65 69 6e 65 6d 20 62 65 73 74 69 6d 6d 74 65 | einem bestimmte| 00000090 6e 0a 43 6f 64 65 2e 28 30 61 29 2e 2e 2e 0a 0a |n.Code.(0a).....|
According to the same scheme, a memory dump would show the content of the main memory, for example program instructions in the machine code or data in the main memory in the respective memory format.