Task Manager: top
Linux common system working commands
man command
View the specific available parameters and object format of the command
echo command
Display string or variable in terminal
date command
Display system time and date
| -d, –date= STRING | Display the time of the specified date |
|---|---|
| -I | Display only dates |
| -r, –reference=document | Display the last modification time of the specified file |
| -R, –rfc-2822 | Output date and time in RFC 2822 format |
| -s, –set=STRING | < span class="md-plain">Set the system time to the specified time STRING |
| -u, –utc, –universal< /span> | Display UTC time (UTC) td> |
| –help span> | display this help message and exit |
| –version | Display version information and exit |
| -b | Display memory usage in Bytes |
|---|---|
| -k | < span class="td-span">Display memory usage in KB units |
| -m | Display memory usage in MB units |
| -o | Do not display the buffer adjustment bar |
| -s | |
| -t | Display the memory sum column |
| -v | Display version information |
who command
The who command displays information about all users currently on the local system. The following are displayed: login name, tty, login date and time. who command can also display the elapsed time since the line activity occurred, the process ID of the command interpreter (shell), login, logout, restart And system clock changes, and other processes generated by the initialization process can also be displayed.
last command
history command
Used to display historical records and executed commands. The history command reads the directory in the historical command file to the historical command buffer and writes the directory in the historical command buffer to the command file.
sosreport command
is used to collect system configuration and diagnose information and output the conclusion document
Linux text file editing commands
cat command
This command is used to view the content of a text file, followed by The name of the file to be viewed is usually piped together with more and less, so that the data can be viewed page by page.
| -n | display line number |
|---|---|
| -b | display line number (not including blank lines) |
| -A | shows “invisible” symbols, such as spaces, tab key etc. |
format: cat [OPTION]… [FILE]… -n : Number the displayed text line -E: Display the end of line symbol $ Example: cat -n /etc/fstab –view /etc/fatab content and display the line number
< h6 class="md-end-block md-heading">more command
< span class="md-plain">For viewing longer plain text files (cat for shorter ones)
< span class="md-plain">head command
View the front of a plain text document N line ——head: display text content, the default display head 10 lines Format: head [OPTION]… [FILE]… -n #: Display text header# line content Example: head -5 /etc/passwd < span class="md-plain">–Display the first 5 lines of the /etc/passwd file< /span>
tail command
View the last N lines of a plain text document
wc command
Using the wc command, we can calculate the number of bytes, words, or columns of the file. If the file name is not specified, or the given file name is “- “, the wc instruction will read data from the standard input device.
| -c or –bytes or –chars | Only display the number of Bytes |
|---|---|
| -l or –lines | Show only the number of lines |
| < span class="md-plain">-w or –words | Show only word count |
| –help | Help |
| –version | Display version information |
p>
Linux Working directory switching command 
ls command: View information in the directory Command format: ls [option] [directory name]
ls command
options
Function description
-a
List all files in the directory, including hidden files beginning with. (All)
-l
List the detailed information of the file
-h
Together with -l, output the file size in an easy-to-read format
–help
display help information
directory switching command cd switch directory < td>automatically complete< /span>
< tr class="md-end-block"> < td>Clear screen
< p> show the current Working directory < p class="md-end-block md-p">Absolute path: YesStart from the root directory (/), which completely represents the path to the target file or directory. Relative path: starting from the current directory, the complete path to the target file or directory. 
cd command
< span class="td-span">Special directory symbols
Meaning
.
Current working directory
..
Parent Directory
~
User Home Directory< /span>
–
previous working directory td>
Several auxiliary operations of command line compilation
Tab key
backslash\
Add \ after a line of command, which means start another line and continue typing< /span>
Up and down arrow keys
find out historical commands that have been executed
Ctrl+U Key
Empty to the beginning of the line
Ctrl+K span>
Empty to the end of the line
Ctrl+L
Ctrl+C
Terminate the execution of the command
pwd command
absolute path and relative path
p>
1. Use the mkdir command to create a directory. For example: mkdir+file name (in the current Create a file under the directory) mkdir /home/stduent/sl (create a folder in the specified directory)
Linux file management commands
mkdir command
options
function description< /th>
-m
Set the permission mode when creating a directory
-p
Create each directory specified in the directory structure, if the directory does not exist, create the directory, if the directory already exists, it will not be overwritten e.g. mkdir -p ./xx/yy/uu
-v< /span>
or –verboss: display information every time a new directory is created
–help
Show help information
Current directory: mkdir s1 s2 s3 Specify the directory: mkdir /home/czs/s2 /home/czs/s3
Preparation: File naming < span class="md-softbreak"> File names and commands in Linux systems need to be case sensitive. Linux supports long file names, up to 256 bytes (without spaces and special characters)< /span>
touch command
Used to create a new empty text file
Example: touch 1.txt
cp command
can be used for directories or files Command format: cp [options] source file target file
< table class="md-table">
Example: Copy 1.txt to the uu directory cp 1.txt uu/ copy 1.txt to the current directory and name it 2.txt cp 1.txt 2.txt will uu directory (including sub File) copied to the sss directory cp -r uu sss/< /span>
mv command
Used to move or rename a directory or file (equivalent to a renaming cut command) command format: mv [option] source file Target file Example: Move 1.txt to the target file mv /mnt/xx/yy/uu/1.txt /mnt/files/ (if it is named 2.txt here, it will be 2.txt after the move is not named, then it will be the original name) change the file name in the current directory mv 2.txt 3.txt
rm command (delete files or directories)
is used to delete files, and can also delete multiple files or directories. Command format: rm [options] target file add On-f will not give a prompt to confirm deletion
< span class="md-plain">rm -f 1.txt rm -rf /mnt/files/ /mnt/s3/ (delete files and s3)
Delete directory Need to add -r Delete directory without prompt-rf
rmdir command (delete empty directories)
Delete an empty directory, and the delete operation must be performed in the parent directory. Command format: rmdir [option] directory name
| options span> | Function description |
|---|---|
| -p< /td> | Delete the specified directory tree |
| -v | < span class="td-span">–verbose outputs diagnostic information during directory deletion |
| –help | Display command help information |
rmdir -p xx/yy/ (need to be empty)
find command (find)
is used to find files that meet the conditions in a relative path. Command format: find the path of the search directory, the search condition option sets the search condition
| Options | function description th> |
|---|---|
| -name | Search by file name |
| -user | Search by username |
| -type | < span class="td-span">Search by file type |
| -size | Find by file size |
| -atime | Find by file’s last access date |
| -mtime | Find by the last modification date of the file |
| -newer | |
| -amin | Find files that have been accessed within a specified time |
| -cmin | Find files that have been changed within a specified time< /span> |
| -perm | Find files that meet the specified permission value td> |
Example: find / -name student
find / -user student
grep command
The grep command is used to search text, the format is: “grep [option] [file] “.
| Parameter | Function |
|---|---|
| -b | treat executable files (binary) as text files ( text) to search |
| -c | 仅显示找到的次数 |
| -i | 忽略大小写 |
| -n< /td> | 显示行号 |
| -v | 反向选择——仅列出没有“关键词”的行 |
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Linux压缩文件命令
tar命令
tar命令用于对文件打包压缩或解压，格式为：“tar [选项] [文件]”。
打包并压缩文件:“tar -czvf 压缩包名.tar.gz 文件名”
解压并展开压缩包:“tar -xzvf 压缩包名.tar.gz”
| 参数 | 作用 |
|---|---|
| -c | 创建压缩文件 |
| -x | 解开压缩文件 |
| -t | 查看压缩包的文件 |
| -z | 用Gzip压缩或解压 |
| -j | 用bzip2压缩或解压 |
| -v | 显示压缩或解压的过程 |
| -f | 目标文件名 |
| -p | 保留原始的权限与属性 |
| 使用绝对路径来压缩 | |
| -C | 指定解压到的目录 |