【转载】Linux Examination
原博地址：https://blog.csdn.net/weixin_42568655/article/details/94603660
（来自我的同学QiaoGuangtong大佬）
Fundamental About Linux
Partition.
Generally, the partitions in linux, take the ubuntu for instance, four partitions are general, which including “/”, “/boot”, “/swap”, and “/home”, in which home is your users’ directory.
File Command
In linux, the file processing commands are pretty important because all your actions are about file processing. So next term, let us to learn about the commands for processing the files.
At first, you should know that the command is case sensitive, for which you should know which are upper case, and which are lowercase.
ls -list directory contents
List the files and directory from current directory order by the first case default.
| Options | Long Option | Describe |
| -a | -all | List all files |
| -l | -long | Display results in long format |
| -t | -time | Display result order by time |
cp -copy
This command can copy files or directories. It can be used two different ways.
cp item1 item2
to copy the file or directory from item1 to item2, and
cp item… directory
to copy multiple items (files or directories) into a directory.
Example:
cp -r item1 item2
Recursively copy directories and their contents. This option is required when item1 is a directory.
mv -move
This command can move file or directory to a new directory and rename a file
Example:
mv item1… item2
Like cp, move files or recursively move directories and their contents. item1 and item2 can be directory or file.
rm -remove
This command can remove the directed file or directory
Example:
rm -r item
The same, recursively remove directories and their contents. This option is required when item is a directory.
rm -f item
This command will cancel warning when you remove a file or directory and its contents.
rm -rf item
This command combined two above.
tar
This command can zip or unzip the directed files or directories.
Example:
tar -czvf item1 item2….
-czvf create zip visual file (new file name)
This command can zip item2, which can be file or directory. item2 can be multiple items.
tar -xvzf item
This command can unzip item, a zip file.
chmod -change mode
This command can change permissions of a file or directory.
Example:
chmod u+x item add execute on item for current user
chmod u+r item add read on item for current user
chmod u+x item add write on item for current user
chmod g+x item g is group add execute for all users in the same group with current user.
chmod a+x item a is all add execute for all users
touch
This command can change the time for visiting and changing. If the file does not exists, create a new file.
option:
touch [filename]
This command can create a new file filename.
find
This command is the most complex in my class that cannot remind me all the time.
find ./ -size -name passwd -ok cp {} /home ;
Directory Command
mkdir
This command can create a new directory
Example:
mkdir item
This command creates a directory item in current directory.
cd
This command can change directory
Example:
cd item
This command changes into item, which is a directory.
User Command
su
This command can change current user to another.
Example:
su sam
This command change user to sam.
passwd
This command can update password for a user.
Example:
passwd sam
This command can update password for sam.
Other Command
cat
This command can display the content of a file. E.g. cat a.txt
echo
This command can display the content of a string or environment variables and so on. E.g. echo java
ps -ef
This command can display the processes of current system.
kill -9 [pid]
This command can kill a process which number is pid.
Vi/Vim
vi is a screen-oriented text editor originally created for the Unix operating system.
vi is a modal editor: it operates in either insert mode (where typed text becomes part of the document) or command mode (where keystrokes are interpreted as commands that control the edit session). When you enter “:” , you will enter last-line mode.
change mode:
i from command mode to insert command
Command mode:
dd delete current line
yy copy current line to buffer
nyy copy n lines to buffer
Last-line mode:
:q quit with no action
:wq save write and quit
:q! force to quit
:x save and quit
. Shell Scripting
- Tips For a new shell scripting, you can make it according the following steps.
- Write your shell scripting file using vi/vim or other editors
- Change its permissions so that it can be executed
- Execute it
- Practice
copy files
copy /etc/passwd, /etc/profile, /etc/shadow to current directory.
1 cp /etc/passwd ./ 2 cp /etc/profile ./ 3 cp /etc/shadow ./
Specific size
Decide if a number is greater than 50.
1 x=50 2 if [ $x -gt 50 ] ; then 3 echo ">0" 4 else 5 echo "<=0" 6 fi 7 8 ./e1
Add 1-100
Display the sum from 1 to 100
1 i=0; 2 sum=0; 3 while [ $i -lt 100 ] ; do 4 let i+=1 5 let sum+=$i 6 done 7 echo "sum is $sum"
Create Files
Please create 100 files f1 to f100
1 i=0;
2 while [ $i -lt 100 ] ; do
3 i+=1
4 touch f$i
5 done
Re-Write cp
Re-Write my copy using two arguments, and decide if the first argument is a directory
1 if [ -f $1 ] ; then 2 cp $1 $2 3 else 4 cp -r $1 $2 5 fi
Ten Score cp
(快考试了排不完了 先不排了）
（有空再弄）
(烂尾预警）
