emptying files with redirects
>the contents of filename =>filename are emptied
Command Help
$ man command
Query the description document for command commands
$ man-k keyword
Query keywords
$Info command
A more detailed description of the document
$whatis command
Brief description
$which command
The path to the binary file where command
$whereis command
All the command in the search path
Here's an example of a command (binary file). For example, man can also be used to query system functions, configuration files, and so on.
User
$Finger username
Display user username information
$ who
Show current logged in user
$ who am I
An interesting usage.
$Write username
Send message to User (end input with EOF)
$su
Become the root user
$sudo command
Execute AS Root user
$passwd
Change Password
SHELL (BASH)
$ History
Show command history under current shell
$alias
Show all commands for the nickname
$alias new_command= 'command'
Call command not New_command
$env
Show all environment variables
$Export var=Value
Set environment variable var to value
$Expr 1 + 1
Calculate the
File system
$du -sh dir
Folder size,-H human-readable units,-s only show summary
$Find . -name filename
Start with the current path and look down for the file filename
$Locate string
Find a path that contains a string
$UpdateDB
Unlike find ,Locate is not a real-time lookup. You need to update the database to get the latest information.
$Ln -s filename path
Create a soft link to the file filename in the path location
$pwd
Show current Path
$CD path
Change the current working path to Path
$CD -
Change the current path to the previous path
File
$Touch filename
If the file does not exist, create a blank file, and if the file exists, update the file read and modify times.
$RM filename
deleting files
$cp file1 file2
Copy file1 to file2
$ls -l Path
displaying file and file-related information
$mkdir dir
Create Dir folder
$mkdir -P Path
Recursively creating paths for all folders on path
$rmdir dir
To delete the dir folder,dir must be an empty folder.
$RM -R dir
Delete the dir folder and all files it contains
$rm-I. Dir
When the Dir folder is deleted, a dialog is prompt
$rm-I. Dir
Prompt once before removing more than three files, or when removing recursively. Less instrusive than-i, while still giving protection against most mistakes
$rm-F Dir
Ignore nonexistent files, never prompt
$file filename
Type description for file filename
$chown username:groupname filename
Change file ownership will be OwneR, owning group
$chmod 755 filename
Change the file's permissions to 755:owner r+w+x, Group:r+x, others:r+x
$od -c filename
displaying files in ASCII characters
File display
$Cat filename
Show Files
$Cat file1 file2
Connection display file1 and File2
$Head -1 filename
Show the first line of the file
$Tail -5 filename
Show file bottom line fifth
$diff file1 file2
Shows the difference between file1 and file2
$Sort filename
Sorts the rows in the file and displays
$Sort -f filename
When sorting, do not consider case
$Sort -u filename
sorting, and removing duplicate rows
$uniq filename
Displays the rows that are not duplicated in the file filename (same content but not adjacent rows, not duplicates)
$WC filename
The number of characters, words, and lines in the statistics file
$WC -l filename
Number of rows in the statistics file
Text
$echo string
Display string
$echo string | Cut -c5-7
5th to 7th columns of truncated text
$echo string | grep Regex
To display a row that contains a regular expression regex
$echo string | grep -o regex
Displays substrings that conform to the regular Regrex
Time and date
$Date
Current date Time
$Date + "%y-%m-%d_%t"
Display datetime in YYYY-MM-DD_HH:MM:SS format (format can refer to $man date)
$Date --date= "1999-01-03 05:30:00"
Shows the datetime from 1900-01-03 05:30:00 backwards 100 days
$Sleep 300
Sleep 300 seconds
Process
$Top
Show process information and update in real time
$PS
Shows the process under the current shell
$PS -lu username
Show the process of user username
$PS -AJX
Show all processes in a more complete format
$Kill PID
Kill PID (PID is process ID)
$Kill %job
Kill Job (Job number)
$lsof -u username
Files opened by the user username process
$DMESG
Show System Log
$ time a.out
Test the run time of the a.out
Hardware
$uname -A
Display System Information
$DF -LH
Display the usage status of all hard drives
$Mount
Show all hard disk partition mounts
$Mount partition path
Hang on partition path
$umount partition
Uninstalling partition
$sudo fdisk -L
Show All partitions
$sudo fdisk device
Create a partitioned table for device (such as/DEV/SDC). After entering, select N, p, W
$sudo mkfs -t ext3 partition
Format Partition patition(e.g./DEV/SDC1)
Modify the/etc/fstab to mount the partition automatically. Add Rows:
/DEV/SDC1 Path (mount point) ext3 defaults 0 0
$Arch
Display schema
$Cat /proc/cpuinfo
displaying CPU information
$Cat /proc/meminfo
Display memory Information
$cat/etc/issue
Show Fedora Version
$ Free
Show Memory usage
$pagesize
Display memory page size (in KByte)
Internet
$ifconfig
Displays the network interface and the corresponding IP address. Ifconfig can be used to set the network interface
$ifup eth0
Running the eth0 interface
$ifdown eth0
Close the eth0 interface
$Iwconfig
Show Wireless network interface
$Route
Displays the route table. The route can also be used to modify the routing table
$netstat
Displays the current network connection status
$Ping IP
Send ping packets to address IP
$traceroute IP
Probing the route path to address IP
$dhclient
Send DHCP requests to the DHCP host for IP addresses and other setup information.
$host domain
DNS query, look for the domain name IP corresponding to
$Host IP
Reverse DNS Query
$wget URL
Use wget to download the resources that the URL points to
$wget -M url
Image download
SSH login and file transfer
$ssh ID@host
SSH login remote server host,ID is user name.
$sftp ID@host
Login Server host,ID is user name. After the sftp login, you can use the following command to further the operation:
Get filename # download file
put filename # uploading files
LS # Lists all files for the current path on the host
CD # Change the current path on host
lls # Lists all files for the current path on the local host
LCD # Change the current path on the local host
$SCP localpath ID@host:path
Upload the file that the local LocalPath points to to the path path of the remote host
$SCP -R ID@site:path localpath
In the SSH protocol, traverse The entire file system in the download path path, to the local localpath
Compression and archiving
$zip file.zip file1 file2
Compress file1 and file2 to file.zip
$Unzip file.zip
Decompression File.zip
$gzip -c filename > file.gz
Compress file filename to file.gz
$gunzip file.gz
Unzip the file.gz . zip file
$tar -cf file.tar file1 file2
Create a tar archive
$tar -zcvf file.tar file1 file2
Create a tar archive and compress
$tar -xf File.tar
Release the TAR Archive
$tar -zxvf file.tar.gz
$tar-JXVF file.tar.bz
Unzip and release the TAR Archive