Linux program and resource management

Article title: Linux program and resource management. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.
Special instructions for online help:
· Query online Linux commands:
Basically, it is better to use the text interface to log on to Linux! This is because, although X-Window is quite powerful for beginners, if X-Window is used only for Linux, what is the difference between X-Window and windows ?! (Of course ??? Why ?? If customized Linux is used as a DeskTop, what should we do differently ??. Just kidding me. maybe X-Window has a lot of sequelae! This is because X-Window can only be regarded as a set of "software" in Linux, not a set of "job Systems". Therefore, X-Window cannot fully master all the functions of your system, in addition, X-Window consumes a large amount of resources during Run, which is terrible for older machines! For example, laruence's P-166 is only 64 MB memory size to come and go, if a run X-Window, then my other network services may be lagging ....! Basically, for anyone who wants to drill into Linux! I hope you can use the text interface to set up all your services. This makes it easy for you to understand the main architecture of Linux and the location of each command and its associated file settings, it will be of great help for your future debugging work! So ??? Chip? Why did you shout? I'm a joke. why don't I try to scream? Why? Private Linux system architecture ". here, laruence strongly recommends using a text interface to operate Linux!
Next we will sort out commonly used commands in different categories, of course ??? Ranning S Mei bucket talk Yan Ruirui around the cutting of the egg and peptide Ke Yu Mu Muyi Mei Jiao Mao Yu Ruirui ya? Why? Playing? Rows? ? I still want to have A plaque with Li yundun? Twisted pair? On a Linux host, instructions for various commands have been built in, and are very detailed online instructions. you can use:
　　
[Root @ tsai root] # man command <= command: name of the command you want to query
[Root @ tsai root] # info command
In the preceding table, you can use man or info to query command functions and instructions. for example, if you want to query the ls command, you can enter: man ls or info ls! Appropriate use of online queries can help your English and related command functions to a certain extent! As for the usage of laruence, the old saying is "Don't be afraid to read English". I will understand it after reading it for a long time! Because laruence's English is not good either (in fact it is very broken), but you can still understand it through hard work! Then, when I started playing Linux, I used to look up an English dictionary ...!
· About online query "parameter setting file structure 』
In addition, if it is a common parameter file, how should we query the setting method ?! Haha! Enter the following parameter!
　　
[Root @ tsai root] # man 5 passwd [root @ tsai root] # man passwd
· Haha! By carefully comparing the two commands provided above, you can easily find the differences between them! How are they different? Hey! The second display shows the usage of the/usr/bin/passwd execution file. However, when the first parameter is set to 5, it automatically becomes the setting function for querying the/etc/passwd file! Remember: "In Linux, when man is used, the query of parameter settings is set to 5 !』 Why is it 5? How to set it? haha! You need to check man's search path (MANPATH!
· Online man pages search path:
Here is an interesting topic for you to think about. Where can I find Linux when I query command usage or when I query parameter file settings !? Haha! Is it found in the MANPATH variable ?? Where can I set the MANPATH when the operator clicks? Well! It is easy to find, that is, the file/etc/man. conf ?? Maomei egiang school? When the hacker invades the man, the system will query the PATH one by one, just like when we execute some execution files! Where is the default MANPATH !? Is in:
O/usr/share/man
O/usr/local/man
The two above are huge! Well, if I have installed a new suite, it will be installed under/usr/local/newpackes using the Tarball, I know that the man pages of this suite are placed under/usr/local/newpackes. how can I make this directory be queried by MANPATH? Very easy! Write the directory to/etc/man. conf!
· File information in the Linux host:
Basically, you already have a lot of files in Linux, but it's just the original! Okay. do you know where the document is located ?! It's in the directory below!
O/usr/share/doc
If you are free, go and check it out! You will see a lot of related information! Great!
· Note the information displayed in front of the screen:
In addition, many error messages have basically provided your solution! When an error occurs, remember to read the error message displayed on your screen !! This is the easiest way to save yourself!
· Keep an eye on the files in/var/log:
Basically, in the case of a Linux preset, all events, large and small, have been written into the log file! If you find a problem with your system at this time, um! Go to this directory and check whether your problem can be solved! Pay attention to it!
　　
Commands for Linux multi-person multi-work environment:
Multiple workers
· Multi-person environment: the best part of Linux is its multi-person and multi-work environment! So what is "multiple workers and more work 』?! In Linux, different people are allowed to use it, and everyone has special permissions. Only one person has the highest power, that is, root (system administrator). apart from others, others must be subject to some restrictions! The setting of the Linux environment can be set by everyone's preferences (remember what we mentioned in the BASH chapter ~ /. Bashrc !? Right! That light! )! Success! Windows is fine! Yes! However, you must know that you can only log on to Windows before Windows. that is to say, only one character can log on to Windows at a time! Of course ??? Indows NT also has the function of multiple workers! However, because NT is too much system resources, I think it is still not as smooth as the Linux or Unix network connections!
· Many ICBC: I think Windows users will always encounter the following: "This file is in use and you cannot open this file !』 Mine! You have to turn off the program in progress before you can open this intermediate temporary archive !! In addition, I am only using it myself ~~ Unable to handle ~~ Haha! Isn't that true for Linux ?? Why? Tip? Bi Huang? Screen? Why ?? Pizhuang? Play games together ??? Mechanical neon? Some friends who are directly in front of the screen are connected over the SSH network ??. Which of the following are allowed? Are you sure you want? Cheonan? What is the form of the inspector? Gray ?? Are you sure you want? Why did the attackers fail? What kind of problem does the egg have? Slide and tricks .. Tu Ti Yun Mei EGU enzyme. Too many tasks? If you have reached the upper reaches of the lower !), Because we have a host dedicated to work, so we are equipped with a relatively high-end (dual piii cpu), then I can carry out two compiler programs at the same time, it will not affect each other, and the resource allocation is quite even! Haha! And discard the resource-consuming Windows services ~ How can it run so smoothly! Awesome !!
· Seven basic Windows: in Red Hat, six text interface logon windows and a graphic interface are provided by default. you can use [Alt] + [F1] ...... [F7] to switch between different terminal interfaces, and each terminal interface can be accessed by different people! Awesome! Unlike Windows, you can only log in to one person in front of the screen at a time !! This is useful! Especially when a program dies!
· Killing the program: the old bird brother was stupid and always thought Windows 98 would work! Later, due to work, I needed to use Unix systems. I wanted to say that I only needed to be in front of the work machine, so I would not have to run to the front of the Unix workstation! So I used Windows to connect to my Unix workstation! I can't die. it takes 2 to get a program running ~ 3 days, alas ~ It is often the second day that Windows 98 hangs up for him! I was afraid of death for him ~~ Later I changed my computer and used a random version of Windows 2000. haha, this is really good (for single users, he can only kill the wrong program without interfering with other programs! Since then, don't worry about connecting machines ?? ? 2000 is not good enough, because sometimes it will die !! What about Linux? Haha! Even better, it can be said that it will never become a machine! Because he can kill a trapped program at any time, and then re-execute the program without restarting it! Nice enough! If I log on to the text interface in Linux, an error message will be displayed on the screen, and then it will be suspended ~ It cannot be moved. how can this problem be solved !? At this time, the default seven windows will help you! You can press [Alt] + [F1]... [F7] to switch to another terminal interface, then use ps-aux to find the wrong program, and then kill it. haha, return to the terminal interface! En ~ Great! Is it normal again ??
· CPU work problems: all the friends who played Windows 98 in the early days should know that the default CPU of Windows 98 is "always running at full speed", and this cannot be said, it should be said that the CPU of windows 98 is always powered on! When the connection is not working, the CPU usage can still reach 100%, so it is easy to cause CPU overheating when the machine is faulty! Although this situation can be solved in NT 2000, or the CPU power-saving software can be added to reduce the temperature, it is still strange! In Linux, there is no such problem. If the CPU is not used, there will be no power-on. haha! Power saving and no heat! Otherwise, you can take a look at the CPU usage of our website, except that when there are too many online WWW users, it will rush to around 30%. other times are low!
Background execution
· Another function is the effort of "background execution. When you enter
[Root @ tsai root] # cp file1 file2 &
In this command string, the file file1 is copied to file2 and placed in the background for execution. that is to say, after executing this command, you can still do other work on this terminal interface! When this command (cp file1 file2) is executed, the system displays the completed message on your terminal interface! Very convenient!
Multiple workers
· There are indeed a lot of benefits for working with multiple people, but there are also management troubles, because the increasing number of users will lead to your management troubles! In addition, due to the popularity of users, when users reach a certain number of people, your machine usually needs to be upgraded, because the CPU calculation and RAM size can be