Fourth session of Linux Learning-Basic concepts of document management and related parts directives

Linux Learning Fourth session

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19. Basic concept of document management

1. Files and directories are organized into a single inverted tree structure;

2. The file system starts with the root directory, with/representation;

3. Root file System (ROOTFS): root filesystem;

4. The file name is case-sensitive based on the file type, because the USB flash drive fat format is the Windows system file type, so the USB stick file is not case-sensitive on the Linux system;

5. To. The opening file is a hidden file;

6. Path delimited use/;

7. The file has two kinds of data, metadata (meta data) and data, the metadata is the file attribute, the data is the file content;

8. File system Hierarchy LSB.
   

20. Parentheses Usage

{} is represented in Linux as a combination, such as Echo file{1,2,3}. {Txt,log}, the left curly brace is combined with the right curly brace Txt,log respectively, the result of the combination is File1.txt,file1.log,file2.txt,

File2.log,file3.txt,file3.log;

[] The relationship expressed or in Linux, such as [19] means 1 or 9,F[ABC] represents FA,FA,FB,FB,FC.

21. Wildcard Characters

*: Match 0 or more characters

?: matches any single character

~: Current User home Directory

~ User name: User Directory

~+: Current Working directory

~-:~ Previous working directory

[admin]: Matches List A, D, M, I, n any one character

[^admin]: matches any one character in the list other than a, D, M, I, n

[:d Igit:]: Any number, equivalent to 0-9

[: Lower:]: Any lowercase letter

[: Upper:]: Any uppercase letter

[: Alpha:}: Any case of uppercase and lowercase letters

[: Alnum:]: Any number or letter

[: Blank:]: horizontal white space character

[: space:] Horizontal or vertical whitespace characters

[:p UNCT:]: Punctuation

[:p rint:]: Printable characters

[: Cntrl:] Control (non-printing) characters

[: Graph:] graphic character

[: xdigit:] hexadecimal character

22. File naming rules

1. The file name is up to 255 bytes long;

2. The file name, including the path, has a maximum of 4,095 bytes;

3. After viewing the file directory with the LS command, Blue is the folder directory, green is the executable file, red for the compressed file, light blue for the link file, gray for other files;

4. In addition to null and/, any character can be used as the file name for Linux.

23. Common Catalogue

/etc/issue Pre-boot text hints

/ETC/MOTD text prompt after boot

/etc/gdm/custom.conf, set the boot-related functions, the image is automatically logged in the user name of the admin account

/ROOT/.BASHRC Setting Custom aliases

/etc/profile.d/custom name. SH prompt format changed, format ps1= "\[\e[1;5;42;32m\][\[email protected]\h \w]\\$\[\e[0m\]"

/proc/meminfo Memory Information Path

24. Special symbolic meanings in variables

View Help, with the instruction man Agetty, appears

Characters commonly used character interpretation

\a Display system date, format: Sunday period
\a Display system time, format: hh:mm
\h Display host name (abbreviation)
\H display hostname (full name)
\ t display system time, Format: HH:MM:SS (24 hour system)
\ t display system time, Format: HH:MM:SS (12 Hour system)
\u Display user Name
\w Display workstation Name

Fourth session of Linux Learning-Basic concepts of document management and related parts directives