<<linux command line Daquan Learn and take notes >> summer study

<<linux command line Daquan learn and take notes >> Summer study

Chapter One: What is a shell?

1 shell

The shell is an explanatory program that interacts with the Linux kernel, and we can interact with the operating system through the Shell terminal emulator under the graphical user .

2 Chapter Command line

Date: display time

cal: Show Calendar

DF: Show disk drive memory

Free : Display system memory

Exit : exit terminal

Chapter II: Navigation

2.1 Understanding the file System Tree

the Linux system uses the tree structure to represent the system's files, directories, and device files.

2.2 Current working directory

The top of the tree is the root directory, usually / represented, and then descending into subdirectories.

The current working directory is set to the home directory when the system is first logged on (or terminal). Each user account has a home directory, which is the only place to allow users to write files, as normal user operations.

2.3 Absolute path and relative path.

The absolute path is the path from the root directory to the directory where it is located.

The relative path is the path from the working directory to some directory, and the relative path operation is usually "." and "." .

An example of an absolute path operation :

Cd/usr/bin

To reach the bin directory from the directory

CD./myduc

Reaching Myduc from the current directory

Cd..

Gets to the parent directory of the current directory.

CD Shortcuts

The CD changes the working directory to the user's home directory.

CD- changes the working directory to the previous working directory

CD ~username changes the working directory to username 's home directory, such as cd~new To change the directory to user new 's Home directory.

Some notes about the file name :

1. With ". "The beginning of the file is hidden, ls-a These files can be listed and placed in the home directory when the user account is created.
2. As with Unix , file names are case-sensitive in Linux.
3. the Linux system does not have the concept of file extensions, but some applications do.
4. Linux supports long filenames, and filenames may contain spaces and punctuation. Note: Do not embed spaces in filenames, and embedding spaces in filenames can make many implementations difficult.

This chapter commands: pwd ,cd, ls