The most distinctive part of a Linux program is the license format. Linux programs use the GPL (GNU General Public License) license format. GPL is a free software license with the following features.
--Freedom to run the program --Freedom to modify the source --Freedom of use and redistribution --Freedom to release improved programs
The kernel is the core part of the OS and is responsible for the most core functions such as direct communication with the hardware.
The part other than the kernel required for the OS to operate. Refers to basic software groups such as file systems, file operation commands, and shells.
Linux provides an interactive command input environment called a shell. ** The shell has two main functions: accepting command (instruction) input ** and ** executing shell script **. A shell script is for "automating command input". Create a command line by line in one file. By executing the created shell script, command execution can be automated.
ls --Used to browse files and directories
ls [option] [File]
-a .Outputs all hidden files starting with
-l Output in long format
-t Sort and output according to the last update time
-r Sort in reverse order and output
cat --One of the commands to check the contents of the file
cat [option]file name
-Display with n line numbers added
more --One of the commands to check the contents of the file --When displaying the contents of a file using the cat command, the display will flow if there are many lines. ――The function that controls the screen and stops scrolling in the middle even if there are many lines is called paging, and the command that realizes it is called pager. --There are more and less commands as typical pagers.
more file name
After opening the file, you can operate it by entering the command as follows
| item | Contents |
|---|---|
| space | Proceed to the next page |
| b | Return to the previous screen |
| f | Proceed to the next screen |
| /word | Search for a word. Jump search results with n key |
| q | Exit the pager command |
less --One of the commands to check the contents of the file --Typical pager commands
less file name
After opening the file, you can operate it by entering the command as follows
| item | Contents |
|---|---|
| space | Proceed to the next page |
| b | Return to the previous screen |
| f | Proceed to the next screen |
| ↑ | Go to the previous line |
| ↓ | Go to the next line |
| /word | Search for a word. Jump search results with n key |
| q | Exit the pager command |
touch --Change file timestamp --The file always has a time stamp (last modified date). You can check the time stamp with the -l option of the ls command. --The touch command changes the last update time.
touch [option] [file name]
--When you execute the touch command, the time stamp of the file is changed to the current date and time. --If the file does not exist, create an empty file.
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