I. Linux basic management commands and Linux management commands

I. Linux basic management commands and Linux management commands

1. Shutdown and restart command

(1) shutdown command: shutdown [Option] Time

Option:-c. Cancel the previous shutdown command.

-H Shutdown

-R restart

Example: shutdown-h now # shut down immediately, root User

+ 10 & # shutdown in 10 minutes

& # Define the absolute restart time

(2) Other shutdown commands (not necessarily saved properly): halt

Poweroff (linux/aix/solaris/bsd)

Init 0 (call system level)

(3) other restart commands: reboot

Init 6

(4) system running level:

① Rhel and suse:

0 Shutdown

1 single user mode

2. Network-less single-user mode

3 has ------- more -------------

4 Reserved

5. logon with GUI at the same level 4

6. Restart

Runlevel: view the system running level and display the previous and current level (the first is N, indicating that the previous running level is not available );

Modify the default level:/etc/inittab

② Debian/Ubuntu:

0 Shutdown

1 single user/system maintenance status

2 users

3 users

4 Users

5 Users

6. Restart

/Etc/inittab to view the running-level configuration files (Mo 2) S and s are in single-user mode

 

2. Disk management commands

Df-h # view partition usage

Fdisk-l # view the number of attached hard disks and Their partitions

Fdisk-cu/dev/sdb # format the hard disk

Mount-a # mount all file systems (mount-o remount/opt only remount/opt)

Umount/opt # uninstall the File System

 

3. Command for viewing computer hardware device properties:

Uname-a # view kernel/operating system information (64-bit or 32-bit version)

-R # kernel version

-N # Host Name (= hostname)

Cat/proc/cpuinfo # view CPU information (= lscpu)

Cat/proc/meminfo # view memory details

Free (-m) # memory size (-s 1 every 1 second)

Ps aux = ps-ef # Process

Lspci-TV # list all PCI devices (-TV is displayed in a tree)

Lsusb-TV # -------------- USB device

Lspci | grep Ethernet # Nic

Lspci | grep audio # Sound Card

Lspci | grep VGA # Video Card

Cat/etc/issue.net # system release version

Cat/proc/version ----------------------

Lsb_release------------------------

Cat/etc/redhat-release ---------------------

4. View clock commands

Tzselect # Real clock partition 5 → 9 → 1 → 1

Cal # display calendar (cal-y 2016)

Date # display system time

-S 12:11 # modify the system time

2012/09/11 # ------------ date

"

Hwclock # display hardware clock (provided by button battery)

-W # synchronize system time into hardware clock

-S # synchronize the hardware clock to the system time

 

5. File Processing Command

(1) ls [Option] [file or directory] # list directory content

-A # Show All files (protecting hidden files starting)

-L # display details (ls-l = ll) (. Indicates ACL permission, 1 indicates reference count, and has been called several times)

-D # view directory Properties

-H # humanized display size

-I # display inode (each file has an ID number)

-I # list file attributes

-T # list file names based on the last file modification time

-F # list file name types (* Common file,/directory, @ Symbolic Link, | operating OS, = socket)

-R # display directory and subdirectory file names

Ls-laR/# display all files under the root

(2) file command # determine the file type

(3) directory file processing commands

① Create a directory: mkdir [-p] [directory name]

Example: mkdir-p xue/id # recursive Creation

② Switch Directory: cd [Directory]

Example: cd ~ # Go to the current user's home directory

Cd -------------------------------

Cd-# enter the last directory

Cd .. # Go to the upper-level directory

Cd. # enter the current directory

Cd ../return the parent directory

Cd ../../

Absolute path: Starting from the root directory, first-level recursive search, "." working directory, "." working directory parent directory. Example: cd ../usr/local/src/

Relative Path: search by reference to the current directory. Cd/etc/

③ Display the current working directory: pwd

④ Delete the empty directory: rmdir [directory name]

⑤ Delete a file or directory: rm-rf [file or directory] (delete it after deletion)

-Rf # Delete non-empty directories

6. copy and paste command: cp [source file or directory] [target directory]

-R # copy the directory ????????????????

-P # joint file property copy (including time)

Mv [original path] [target path] # Move and rename

(4) command for viewing file content:

Nl # display row number

Cat # do not show the row number (all file content)

More # display %

Less # % not displayed (display by PAGE, Ctrl + B backward, Ctrl + F forward, enter a line to display, q Exit)

Head # first 10 rows (head-2)

Tail # the last 10 rows

(5) file link:

Hard link soft link (symbolic link)

Ln [source file] [target file] ln-s [source file (absolute path)] [target file]

① Files only ① files can be Directories

② Multiple files, one node ② one file, two nodes

③ Not cross-path, cross-partition ③ cross-path, cross-partition

④ One change, the other will also (differentiate cp) ④ modify any file, and the other will change

⑤ Delete source file, available (front backdoor) ⑤ Delete source file, unavailable (similar to shortcuts)

6. It has the same I node and block and can be considered as the same file. ⑥ Have their own I nodes and block blocks, but data

It can be identified by I nodes. Only the file name and I node of the original file are saved in the block, with no actual data.

(6) file search command:

① File search command: locate

② File -----------: find

③ Command -----------: wheris and which

④ String ----------: grep

⑤ Difference between find and grep:

(7) file search command

① Locate

# Locate yum. conf | grep conf $

# Updatedb update database

② Whereis

# Whereis yum. conf

③ Which

# Which yum find the absolute path of the executable command

④ Find is based on hard disk search and does not rely on databases

# Find/etc/-name "*. conf" | more: find the file with the suffix. conf and layer it

# Find/etc/-name "*. conf"-size + 20 k search for files with a suffix greater than 20 k. conf

# Ll-h/etc/lvm. conf check the lvm. conf size

# Du-a-k/etc/lvm. conf to view the file size

# Find/etc/-name "*. conf "-size + 20 k-exec du-a-k {}\; cp {}/ opt/\; view the file larger than 20 k, display the file size, and copy it to opt

\; # Line feed

# Ls/opt View File Content