Linux tutorial 4

I believe many new users who want to learn linux are wondering what linux learning courses are good. the following small series will collect and organize several important tutorials for you to learn, if you want to learn more, go to the wdlinux school to find more tutorials.

I believe many new users who want to learn linux are wondering what linux learning courses are good. the following small series will collect and organize several important tutorials for you to learn, if you want to learn more, go to the wdlinux school to find more tutorials.

1. installation of software in linux

There are two main types of software installation in linux:

1 Software Package Installation

2. source code compilation and installation

In fact, the software package is installed by someone else or company. The system version is compiled for a specific platform, and the package is prepared.

The source code is compiled by means of the source code, manual, configuration, compilation, and installation.

The two have their own strengths and weaknesses.

Software Package Installation

1. simple, convenient, and fast

2. select different software packages for specific environments and versions.

Source code compilation and installation

1. flexible, customizable, and optimized

2. relatively complicated and have certain basic requirements for operators

3 It takes a long time, especially some software or large software, such as mysql

For the installation of software packages, different Linux branches have different software packages.

For example, wdOS, CentOS, and Redhat all use RPM packages.

For example, Ubuntu and Debian use DEB.

But the source code installation is basically the same for all Linux and unix, except for parameters

Which one is better? No standards, depending on your needs and situations

2. time zone settings:

To ensure that the time is correct, set the time zone correctly. The correct setting is only for better time understanding and other maintenance.

Setting method:

1.

Manually set the time zone:

For example, set the UTC + 8 time

Ln-sf/usr/share/zoneinfo/Asia/Shanghai

/Etc/localtime

Edit ZONE = "Asia/Shanghai" in/etc/sysconfig/clock"

2.

Set using graphical commands

System-config-date (RedHat and CentOS only in most cases) or tzselect can be used as instructed by the command.

3. what is a directory in linux? Absolute directory? Absolute path? Relative directory? Relative path?

Friends who are used to windows know that C, D, and E have no idea about directories and absolute paths.

However, if you are familiar with computers, DOS, or windows commands

But there are still C, D, e, and so on. This windows method of directory

But in Linux, there is no drive letter concept in Linux. everything is a directory and a file.

A directory is used to store an organizational structure of a file and also to locate a file. you need to know where to store or create a directory, or where to find, so you know and understand

Windows has many drive letters.

But Linux has only one root directory, and all other directories are under the root directory or lower-level directories.

The specific directory structure is not described here. if you are interested, you can view related books and documents.

Here we mainly want to describe the absolute directory and absolute path.

In fact, the absolute directory and absolute path are the same thing, but their names are different. I understand this.

Another term is relative directory and relative path.

This is a bit like a reference object in physics.

To compare a reference object to the current directory, you can use the current directory as the relative directory to search for or CD.

What is an absolute directory?

This term is often heard or seen in Linux, and has been seen in the background of wdcp, just like this article.

Http://www.wdlinux.cn/bbs/thread-1506-1-1.html

This article also appears here because of this article.

This is easy to understand.

The first character at the beginning of the directory name is/. it indicates the absolute directory.

Others can be understood as relative directories. the representation method is usually ../

Remember that there are two vertices. one vertex is the current vertex, the other two vertices are the upper vertices, and so on.

Here are the following commands:

Cd

This command can be used to change the directory to the directory path to which you want to go, such

Cd/etc

Go to the/etc directory, that is, change the current directory command.

List the current directory

Pwd

For example, if we use the root user to log on to ssh and run pwd

/Root

This is our current directory and the user's main directory.

If it is a common user, it is usually in the/home directory, such

/Home/wdlinux

Then let's take a look at the path directory and the relative directory.

For example, we are in the/root directory, that is, the current directory.

We are going to the/home/wdlinux directory.

There are two methods

One is the absolute path method, such

Cd/home/wdlinux

One is the relative path method, such

Cd ../home/wdlinux

The previous two can know which one is simpler

Therefore, it is quite effective to memorize absolute directories and use absolute directories.

At first, I thought that two sentences could be cleared, but now I find that it is not.

It seems that the parsing is not clear enough.

4. delete, clear, and set the eaccelerator cache

The eaccelerator itself has the automatic clearing function. the specific settings are as follows: eaccelerator. shm_ttl = "600"

When the eAccelerator fails to obtain the shared memory size of the new script, it will delete all script caches that cannot be accessed in the last "shm_ttl" seconds from the shared memory. The default value is "0". that is, no cached files are deleted from the shared files in the spring.

Eaccelerator. shm_prune_period = "600"

When the eAccelerator fails to get the shared memory size of the new script, it will try to delete the cache script earlier than "shm_prune_period" from the shared memory. The default value is "0". that is, no cached files are deleted from the shared files in the spring.

Therefore, if it is not set to 0, it will be automatically cleared. if it is set to 0, it will be manually cleared.

Manually clear the directory. you can directly cache sub-directories in the directory. restart the web service and clear the sub-directories in the eaccelerator panel.