The next day beginner Linux
ls command
ls: lists the directory contents
ls -a view hidden files ... (to shadow hidden files beginning point, display the current directory and parent directory).
LS -A view hidden files do not include ....
LS View -r reverse directory
ls - l directory listed a long list of
hidden files in the home under the ls -a / home viewing roots.
cal View Calendar
cal 2019 show 2019 calendar
cal 06 2019 show in June 2019 calendar
Create an alias
Method one
alias qwer = 'ls' ls command to create an alias qwer
unalias qwer delete the alias
Method Two
vim /.bashrc
write
alias qwer = 'ls'
the Shift +;
WQ save and exit
source .bashrc file so that the entry into force
exit
sign in again
file type
There are seven Linux file types: regular files, directories, files, file character device, block device file, socket file, symbolic link, the pipeline file.
1. Ordinary file
shown in FIG first 10 characters of the first character - such files as regular files. Such files typically used to create a number of related applications, such as image tools, documentation tools, filing tools
2. catalog file
as shown in FIG first 10 characters of the first character d (directory), this file is a directory file
3. device file
3.1 character file device
shown in FIG as c (character), such as a document file shown in FIG character device first 10 characters of the first character.
Character device file that is the sequence number of peripheral devices such as a keyboard, mouse or the like. Features of these devices is "one read," can not truncate the output.
3.2 device file
as shown, the first ten characters of the first character b (block), a block device such as a document file
block device file: a bridge between user space and kernel space, by the file descriptor block device able to find a device driver in the kernel. Some data is stored, to provide a system random access peripheral devices.
4. Link File
As shown, the first ten characters of a first l (link), this file is a symbolic link file
4.1 symbolic link (soft link) : is a file that points to the directory stored in a another local file (the original file). (Equivalent shortcut under Windows)
LN -s AA bb
original document file link
two files
4.2. Hard-linked files (the equivalent of a copy, should be connected to a number of times at least, on behalf of the original document itself)
LN AA bb
original file links file
is equivalent to a two file names
5.socket file
when we start the MySQL server will generate a file mysql.sock
6. Pipeline file
when we create a named pipe, displays the file properties for pre-r-r-, which begins with p open on the pipeline file
Wildcards and their meanings
Wildcard Meaning
* * represents any number of characters
? Represents any one character, at least one
[] represents any one group of characters matched
[abc] matches any a, b, c in a
[AF] matched to the f a range from any one character
fhs Filesystem Hierarchy Standard
boot
开机引导文件
dev device设备
作为访问外部设备文件的接口
etc （editable text configuration）
用来放置配置文件
home
普通用户家目录
media 挂载点目录
用于挂载多媒体目录
自动挂载目录
mnt （mount）挂载点目录
用于被系统管理员使用，手动挂载一些临时媒体设备的目录
root root的主目录
/根目录 bin
主要用于具体应用
sbin
主要用于系统管理
只能root用户使用
srv（server）
主要用于存储本机或本服务器提供的服务或数据
var 存放可变文件的目录
系统产生的不可自动销毁的缓冲文件、日志记录（包括：mail、数据库文件、日志文件）
tmp（temp）
保存在使用完毕后可随时销毁的缓存文件
（有可能有系统或程序产生、也有可能是用户主动放入的临时数据、系统会自动清理）
usr（Unix software resource ）Unix软件资源
是Unix操作系统软件资源所放置的目录，而不是用户数据，所有系统默认的软件都会放置在/usr
