(Ask Ubuntu)
1-- Hard link : ln command have different parm. Hard link means that the two files is connect together for backup the original files.If you edit any of the two files , it will be sync immedietely. If you delete the original file. It will make all files used. If you delete the copy file , it will keep the context of the original file. This command can not link the directory but single file. ln A.txt B.txt
2-- Symbolic link: This is different from the hard link. This command can link the directory. This one is more usefull than Hard link. ln -s A.txt B.txt
3-- cat : cat is a command which can read the .txt .py .c etc without opening the origin files. Used like this: cat filename.suffix zcat is another command which can read the zip files : zcat filename.zip.
4-- du -sb;df -i : read the Memory and disk used and the information of the device.
5-- ln : The explaination have already said in the point 1 and the point 2.
6-- fdisk : fdisk /dev/sda1 check the information of this device. The memory,sector,node and so on.
7--df : df / command is for checking all device.df -i more information about all the device.
8-- while there is a question about that : sudo apt-get update . Then there is two errors say:”Could not get lock /var/lib/dpkg/lock” .And “Unable to lock administration directory(/var/lib/dpkg),is anther process using it?”.
That two error’s information tell us that we need to find out that whether there is anther process is using the dpkg. So we need to type anther command into the Terminal like that: sudo lsof /var/lib/dpkg/lock. Then it return some information like that :
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
unattend 9241 root 5uW REG 8,1 0 699848 /var/lib/dpkg/lock
So, We need to kill the process like this :sudo kill -9 9214 .(The fromat: sudo kill -9 <PID>).
After these steps ,I can run the system normally. Congratulations!
9--when I moving the Ubuntu Terminal. It receive a command(Ctrl + C) to shutdown the process running in the Terminal. So need to solve this problem like this : Shutdown the processing running in your Original system(Our Ubuntu is install in the Vmware as a Vitrual Machine), The named of the process is YouDao Dictionary!
10--Error:Unable to find the remote helper for https:When I was upload the C files into the remote repository, it show like this error. After finding the answer, It said that the path named /usr/lib/git-core is not in the System’s PATH. So what we need to do is to set the path to include the git-core path so that we can use the command of git: PATH=$PATH:/usr/lib/git-core.
11-- When I try to change my authority to be a root, It turn out to be that Authourity failure. So I am going to find the reason. At last it told me That I have not set the root’password before.We are asked to set a new password for root. We set the password for root used this command: sudo passwd root .After running this command, it asks you to input the password of user now time, then you need to enter the password for root.
12-- When I am using git to manage my code.
There is some steps for you to do this(This for you to update your code to the github.com!).
Step1 : Go to the the file directory which you want to manage the code use the command ‘cd’. After yo u get into the directory, you need to use the first git command: git init -→this command make the directory to be a local repository. The later steps is based on this directory.
Step2 : You need to know the status of the directory, using this git command to get the status: git status. After you using this command. There show the status of the directory. Then you need to add these new files into the commit like this: git add filename.
Step3 : When you finished to add the new files into the commit. Now you can commit those files into the local repository. The command like this: get commit -m filename. After this step, you can check the status of the directory like this:git status to insure that there is no files is new needed to be update.
Step4 : There is two different positions. If you have not connect this local repository to the remote repository located in the service machine of the git.com. You need to do like this : git remote add origin https://github.com/user name/repository’s name,git . After this o peration, the local repository will link with the remote repository located in the service of github,com. Notice: We must insure that there have already make a repository in your github account of github.com. If you have already link your file s to the local repository with the repository in github.com, You just skip this step and read the next step.
Step5 :After all those operations, The last step you need to do is :git push -u origin master .
There is some steps for you do this(This is for you to clone the files from the github.com).
Step1 : You don’t need to add a new directory in your local computer. You just need to type this in your Terminal : git clone https://github.com/githubusername/local-repository-name.git
13-- mkfs : The long form is : Make your file system
14-- badblocks : This command is for you to check whither there are some break sectors in the memory device. It takes more time.
15-- mount : mount commad is important. If you want to operate some devices, it firstly should be mount on. Mount -l command means to show all the devices have been mount on. Mount /dev/sda1 means to mount on the device you want to mount, once mount on, you can use it.before you eject the devices , you should firstly umount the divice like this : umount /dev/sda1 . Then you can eject the device. For example(You want to operate your flash device):
Step1 : df -i show all the device been connect to the operation system.
Step2 : mkdir /media/flash To make a directory to operate the flash device with this file.
Step3 : mount /dev/devicename /media/flash To mount the device on the system’s file.
Step4 : Do what you want to do on the flash directory in order to operate the flash device.
16-- umount : umount /dev/sdb1
17-- rm -rf : rm -rf file’directory. This command can directly delete the whole file directory.
18-- cp -r : cp -r /Original directory /Destination directoryCopy the whole directory.
19-- dumpe2fs :
20-- e2label : e2lable /dev/sab1 MM1994UESTCChange the device name.
21-- hdparm : hdparm /dev/sda1To show the parameters of device connect to the operate Sys.
22-- Some file’s suffix inform us the compress type of the file:
*.Z compressed by compress App
*.gz compressed by gzip App
*.bz2 compressed by bzip2 APP
*.tar Have not been compressed, Open with tar App
*.tar.gz packed by tar App, also been compressed by gzip App
*.tar.bz2 Packed by tar App, also been compressed by bzip2 APP
The Compress Command:
gzip :
bzip2 :
gunzip :
tar -jcv -ffilename.tar.bz2 filename
tar -jxv -ffilename.tar.bz2 -C filename
tar -zcv -ffilename.tar.gz filename
tar -zxv -ffilename.tar.gz -C filename
The package Command:
tar : tar -c -ffiledirectoryname.tar original filename
23--mv : Acommad that can also change the filename. Mv A.txt B.txt
This command also can be used as moving the file into another place.
24-- alias : To rename the command with another name. EG: alias lm=’ls -al’ means that to use the lm name to respect the command ls -al.
25--declare -i number=$RANDOM*10/32768; echo $number
26-- history :
27-- vim -r .filename.swp : This command can help you to recovery the file that have not been saved before which suddenly be killed without saved.
28-- To install the MySQL on your Ubuntu Operation System.
Step1 :sudo apt-get install mysql-server
Step2 : apt-get install my-client
Step3 : sudo apt-get install libmysqlclient-dev
After those steps , Let us check whether the Mysql-server been installed on our Ubuntu’system
Command:sudo netstat -tap | grep mysql
If ubuntu’s terminal shows that your mysql’socket is in listening means that the mysql-server has been installed successfully.
29-- How to remove some App That we don’t want to use!
Step1 : sudo apt-get remove mysql-server mysql-client mysql-common
Step2 : sudo apt-get autoremove
Step3 : sudo apt-get autoclean
If you are trying to reinstall the mysql server ,and there is some problems,please redo the three steps above and then execute the follow command as this :
Step4 : sudo apt-get remove - -purge mysql-\*
Step5 : sudo apt-get install - -reinstall mysql-common (The most important command!)
Step6 : sudo apt-get install mysql-server mysql-client
We also can use this command to do this：sudo dpkg --purge Software
30-- How to stop/start the mysql-server under ubuntu?
sudo service mysql start(Notice:In order to prevent the system have already open the service for you while you continue try this start command , sudo service mysql restartis better!Also,you can use this command to find out while the mysql service is running:service mysql status)
sudo service mysql stop
sudo apt-get install ksnapshot
31-- Error：could not get lock /var/lib/dpkg/lock -open 出現這個問題的原因可能是有另外一個程序正在運行，導致資源被鎖不可用。而導致資源被鎖的原因，可能是上次安裝時沒正常完成，而導致出現此狀況。
解決方法：輸入以下命令
sudo rm /var/cache/apt/archives/lock
sudo rm /var/lib/dpkg/lock
刪除完上面的東西之後有可能會出現下面的問題（Kylin中遇到過）：dpkg 被中斷，您必須手工運行sudo dpkg --configure -a解決此問題，但是按照提示輸入命令之後還是沒有解決問題，下面是解決辦法：
sudo rm /var/lib/dpkg/update/*
sudo apt-get update
sudo apt-get upgrade
32-- can't use the command shutdown：
solution1:
echo $PATH
PATH=$PATH:/sbin
solution2:
/sbin/shutdown