Ls
-L Long format
File type: the
-Ordinary files
D; catalog file
B: Block device files (blocks)
c; Character device files (character)
l; Symbolic link files (symbolic link file)
p; command pipe file (pipe)
s; socket file (socket)
File permissions: 9 bits per 3-bit group, each group: rwx (Read, write, execute)
Number of hard links to files
Owner of the file
Genus Group of files
File size (size), default unit is byte
Timestamp (timestamp), Last modified time
Access: Access
Modified: Modify file contents are changed
Change: The change is metadata, the meta-data
-H: For unit conversions
-A: Show hidden files starting with.
. Represents the current directory
.. Represents the parent directory
-A: Show hidden files but not include. and.
-D: Display the directory's own properties
-i:index node, Inode displays the miniature nodes of the file
-R: Reverse Display
-R: Recursive (Recursive) display
Cd:change Directory Switch Directories
Home directories, home directories, home directory
CD ~ USERNAME: Enter the home directory of the specified user
CD-: Switch back and forth from the previous directory to the current directory
Command type:
Built-in command (shell built-in), internal built-in
External command: There is an executable file corresponding to the command name in a path on the file system
Environment variables: named memory space
Assigning values to variables
Name=jerry
Path: separated paths with colons
O (1)
Type: Shows which type the specified command belongs to
Hash: View Cache,
Data: Time Management
LINUX:RTC (really time clock)
NTP: Network Time Protocol
Hardware Clock Hwclock
System clock
Get help with the use of commands;
Internal command:
Help COMMAND
External command:
COMMAND--help
Command manual: Manual
Mans COMMAND
Whatis command--view commands appear in the first few chapters
Sub-chapters:
1. User commands (/bin,/usr/bin,/usr/local/bin)
2. System calls
3. Library users
4. Special documents (equipment files)
5. File format (configuration file syntax)
6. Games
7. Miscellaneous (Miscellaneous)
8. Management commands (/sbin,/usr/sbin,/usr/local/sbin)
<>: Must be given the
[]: Optional content
... : Multiple occurrences can occur repeatedly
: Choose one More
{}: Grouping has no special meaning
Mans:
Name: command names and features brief description
Synopsis: Usage notes, including available options
DESCRIPTION: A detailed description of the command function, which may include the meaning of each option
Options: Explaining the meaning of each option
Files: Related configuration file for this command
BUGS:
EXAMPLES: Use Cases
See ALSO: Another reference
Flip Screen:
Turn back one screen: space
Turn One screen forward: b
Line backward: Enter
Forward line: K
Find:
/keyword: Backwards
N Key: Next
N Key: Previous
? KEYWORD: Forward
N Key: Next
N Key: Previous
Exit: Q
Online Documentation:
Info Conmmand
Document:/usr/share/doc
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Apache,hadoop,
Hwclock Viewing hardware time
-s hardware clock to System
-W system clock to hardware
Linux Fundamentals 1