ASCII query mode. view files in ASCII format. OD command,

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With the rapid development of computers, many people begin to learn about Linux and learn how to learn Linux commands well. To learn about Linux, you may have knowledge about the Linux Command OD. Here we will introduce the Linux Command OD application method.

Linux Command: OD

Example: OD-C hello

Linux Command: OD

Od command
Users usually use the OD command to view the content of files in special formats. You can specify different options for this command to display files in decimal, octal, hexadecimal, and ASCII code.

Syntax: OD [Option] file...
Meaning of each option in the command:
-A specifies the address base, including:
D decimal
O octal (default)
X hexadecimal
N do not print the displacement value
-T specifies the data display format. The main parameters include:
C ASCII character or backslash Sequence
D. Signed decimal number
F floating point number
O octal (the default value is 02)
U unsigned decimal number
X hexadecimal number
Other options except option C can be followed by a decimal number N, specifying the number of bytes contained in each display value.

Note: The default display mode of the OD command system is octal, which is also the origin of the command name (octal
Dump ). However, this is not the most useful display method. The combination of ASCII code and hexadecimal code can provide more valuable information output.

For example:

 
 

  
  
$ OD-Ax-tcx1 WH5Note: The parameter sequence OD-Ax-txc1 WH5 reports an error.
  
  
000000 f I L E S Y S T E M
  
  
46 69 6C 65 73 79 73 74 65 6D 20 20 20 20 20
  
  
000010 1 K-B l o C K S
  
  
20 20 20 20 31 6B 2D 62 6C 6f 63 6B 73 20 20
  
  
000020 u s e d a V A I L A B
  
  
20 20 20 55 73 65 64 20 41 76 61 69 6C 61 62
  
  
000030 l e u s e % m o u n t e d
  
  
6c 65 20 55 73 65 25 20 4D 6f 75 6e 74 65 64 20
  
  
 
  
  
---- My test -----
  
  
Ysun @ linetcps1dev :~>Cat
  
  
Hello, world.
  
  
Joey.
 
 

 
 

  
  
ysun@linetcps1dev:~> od -Ax -tcx4 a  
  
  
000000 h e l l o , w o r l d . /n /t J o  
  
  
6c6c6568 6f772c6f 2e646c72 6f4a090a  
  
  
000010 e y . /n /n /0 /0 /0  
  
  
0a2e7965 0000000a  
  
  
000015 
 
 

OD and hexdump
The utility OD and hexdump output the octal, hexadecimal, or other encoded bytes of the file or stream respectively. They are useful for accessing or visually checking characters in files that cannot be directly displayed on the terminal.

Here document
There is a special redirection that is worth mentioning in this tutorial. Strictly speaking, the here document is a shell such as Bash.
But they provide a useful way to send special data to a text utility.
Dual-sign redirection can be used to receive the contents of pseudo files from the terminal. The here document must follow <to specify a termination separator.
For example:

 
 

  
  
$ OD-C<End$ OD-C-Ax-tcx1<End: As shown above
  
  
>Alice
  
  
>Bob
  
  
>End
  
  
0000000 a l I c E/n B o B/n
  
  
0000012
 
 

Any string can be used as a separator. The input terminates where the string itself is encountered on a line. This provides a quick way to create a persistent file:

 
 

  
  
$ cat myfile <<EOF 
  
  
> Dave  
  
  
> Edna  
  
  
> EOF  
  
  
$ hexdump -C myfile  
  
  
00000000 44 61 76 65 0a 45 64 6e 61 0a |Dave.Edna.|  
  
  
0000000a 
 
 

This is the knowledge of Linux Command OD.

Edit this section to query ASCII characters: Create a text document and press and hold Alt + the code value to be queried (Note: Here it is decimal) release to display the corresponding characters. For example, if you press Alt + 97, 'A' is displayed '.

Standard ASCII table

Bin	Dec	HEX	Abbreviations/characters	Explanation
00000000	0	00	Nul (null)	NULL Character
00000001	1	01	Soh (start of headling)	Title start
00000010	2	02	STX (start of text)	Start of Text
00000011	3	03	Etx (end of text)	Text ended
00000100	4	04	EOT (end of transmission)	Transfer completed
00000101	5	05	Enq (Enquiry)	Request
00000110	6	06	Ack (acknowledge)	Receive notification
00000111	7	07	BEL (Bell)	Ring tones
00001000	8	08	BS (backspace)	Return
00001001	9	09	HT (horizontal tab)	Horizontal Tab
00001010	10	0a	LF (NL line feed, new line)	Line feed key
00001011	11	0b	Vt (vertical tab)	Vertical Tab
00001100	12	0c	Ff (NP form feed, new page)	Page feed key
00001101	13	0d	Cr (carriage return)	Enter key
00001110	14	0e	So (shift out)	No switchover
00001111	15	0f	Si (shift in)	Enable Switch
00010000	16	10	Dle (Data Link escape)	Data Link escape
00010001	17	11	DC1 (Device Control 1)	Device Control 1
00010010	18	12	DC2 (Device Control 2)	Device Control 2
00010011	19	13	DC3 (Device Control 3)	Device Control 3
00010100	20	14	Dc4 (Device Control 4)	Device Control 4
00010101	21	15	Nak (negative acknowledge)	Reject
00010110	22	16	Syn (synchronous idle)	Synchronization idle
00010111	23	17	Etb (end of Trans. Block)	Transfer Block ended
00011000	24	18	Can (cancel)	Cancel
00011001	25	19	EM (end of medium)	Media interruption
00011010	26	1a	Sub (substitute)	Substitutes
00011011	27	1B	ESC (escape)	Overflow
00011100	28	1c	FS (File separator)	File delimiter
00011101	29	1D	GS (group separator)	Group Operator
00011110	30	1e	RS (record separator)	Record delimiter
00011111	31	1f	US (Unit separator)	Unit Separator
00100000	32	20	(Space)	Space
00100001	33	21	!
00100010	34	22	"
00100011	35	23	#
00100100	36	24	$
00100101	37	25	%
00100110	38	26	&
00100111	39	27	'
00101000	40	28	(
00101001	41	29	)
00101010	42	2a	*
00101011	43	2b	+
00101100	44	2c	,
00101101	45	2d	-
00101110	46	2e	.
00101111	47	2f	/
00110000	48	30	0