Various small commands and directories for Linux

PWD Displays the current working directory

W

W.H.O.

WhoAmI

Displays the current user and the established SSH link

Useradd create a new normal user

passwd Modifying a user's password

# represents the root Superuser who is currently working

$ represents a regular user who is currently working

There are two types of shell commands

One is that the built-in commands are provided directly by the kernel

One is that an external command is provided by a binary program on the system

Which view the path to the system command

Type query whether the command belongs to an internal command or an external command

A hash of a command a text produces a string of characters through an algorithm.

DF View System Partition

Hash-l speed up command query execution

Alias queries existing aliases in the system

Ls-a viewing hidden files in the current directory

Unalias canceling command aliases

There are three ways to directly execute the original command without using an alias

\\\\cmd

' CMD '

/path/cmd

Shutdown-r "Guanji Gundan" =reboot

Shutdown-c Cancel shutdown

RunLevel view 6 levels of system run level

Init 0 shutdown

Init 6 Restart

Echo Echoes

Command 2Tab all commands line completion

String2tab start with a string command

/2tab Show all directories below the root directory, including hidden directories

./2tab current directory subdirectory, including hidden directory ls-da./*

*2tab current directory subdirectory, excluding hidden directory ls-d./*

~2tab List of all users

$2tab All variables

@2tab/etc/hosts record (CENTOS7 not supported)

=2tab equivalent to Ls–a (CentOS 7 not supported)

！ String repeatedly executes a command preceded by a string

!? String repeats the previous command containing string

^string Delete A string from the previous command

^string1^string2 Replace the first string1 in the previous command with string2

!!:gs/string1/string2 Replace all string1 in the previous command with string2

Ctrl + L cursor moves to the beginning of the command, equivalent to home

Ctrl + eLinux directory

/boot kernel-related files grub kernel and bootloader

/root directory

├──bin the basic commands that the user uses (executable, binary) cannot be partitioned separately

├──boot kernel-related files grub kernel and bootloader

├──cgroup for resource-constrained resource isolation docker containerized

├──dev Device Equipment files

B Block device block set U HDD or CD-ROM random read/write

c Character device character devices fax mouse typewriter sequential Read and write

├──ETC various systems including application configuration file Usage frequency Super five-star

├──home Each user's home directory and the default working directory for each user

The ├──lib program includes some shared library files that the system relies on and the module files that the kernel depends on.

├──lib64 the library files that the System program relies on

├──lost+found Garbage Collection Station

├──media CD or USB stick mount point

├──misc miscellaneous bad Things to categorize

├──mnt Temporary file mount point

├──net Network Files

├──opt third-party application installation location

├──proc pseudo file system hard disk does not exist, only exist in memory, record the operation information of the system or process Cpuinfo

├──root Root's home directory

├──sbin Storage Management class commands cannot be partitioned separately

├──selinux files or records related to SELinux

├──srv some files produced by the system operation

├──sys pseudo file system records some operational information of the system hardware

├──tmp Miscellaneous, temporary files, and application-generated temporary files

├──usr mistakenly thought User,unix software resource

/lib/lib64/bin/sbin

/local used to store third-party applications

/share for storing help

/etc/configuration file

/include mainly used to store header files

/tmp temp file

└──var log storage and application generated some files or temporary file Mail queue Usage frequency Super five-star

/var/log/message System Log

/var/log/boot.log Some logs generated when the system starts

/VAR/LOG/DMESG output kernel or some useful information of the hardware, you can use DMESG

/var/log/mail.log log generated by mail

/var/log/cron system and our customized log of scheduled tasks

/var/lib/mysql MySQL Data storage directory

/var/mail Mail directory because the mail service this directory may be full rsync (command) use an empty directory to synchronize the problematic directory

<span class=\ "\ \" apple-tab-span\\ "\" style=\ "\" white-space:\ ">/var/spool/cron content related to Scheduled tasks

Various small commands and directories for Linux