Operating System and Common commands
Linux02
-- Linux02_01? Operating System and Common commands
GNU: GNU is Not Unix.
GPL: General Public License, General Public License, copyright
Copyright, Copyleft
Open-source protocols
LGPL: lesser
GPLv2
GPLv3
Shell:
GUI: Graphic User Interface
Windows
X-Window
Gnome
KDE
Xface
CLI: Command Line Interface
Sh
Bash
Csh
Ksh
Zsh
Tcsh
Google:
Linux filetype: pdf
Linux site: ibm.com
Google hack
IDE: integrated development environment
Login:
User name: User ID
Authentication Mechanism: Authentication is the object mechanism declared for identification and determination.
Authorization: Authorization
Audit: Audition (log)
Prompt, Command prompt:
Command:
Magic number: magic number
Shebang
#! /Bin/bash
# Command options... arguments... (Operation object)
Option:
Short options
Long Options
Parameters:
List: ls
List
Directory: file, path ing
Path: from the specified start point to the destination location
File system: file system
FHS: hierarchical File System
List objects in a specified path
Directory: working directory, current directory
Pwd: Printing Working directory
Ls
-L: long format
File Type:
-: Common file (f)
D: directory file
B: block Device Files)
C: character device file (character)
L: symbolic link file)
P: Command pipeline file (pipe)
S: socket File)
File Permission: 9 bits, each 3 bits, each group: rwx (read, write, execute), r --
Number of file hard links
File owner)
File group)
File size (size), in bytes
Timestamp: The last modification time.
Access: access
Modify: modify. The file content has changed.
Change: change, metadata, metadata (attribute)
-H: converts units.
-A: displays hidden files starting ".".
. Indicates the current directory
.. Indicates the parent directory
-
-D: displays the directory attributes.
Drwxr-x --- 18 root 4096 Jan 28.
-I: index node and inode (display index node number)
851969 drwxr-x --- 18 root 4096 Jan 28.
-R: reverse display
-R: recursive display
.:
Anaconda-ks.cfg DOS install. log Unix
C exit install. log. syslog vms
Desktop grant Solaris
Cd: change directory
Home directory, home directory, home directory
Cd ~ USERNAME: Enter the Home Directory of the specified user, but only the root permission can enter the directory of another user
Cd-: switch back and forth between the current directory and the previous directory
[Root @ localhost ~] # Cd ~ Oracle
[Root @ localhost oracle] # pwd
/Home/oracle
[Root @ localhost oracle] # cd-
/Root
[Root @ localhost ~] # Cd-
/Home/oracle
[Root @ localhost oracle] # cd-
/Root
[Root @ localhost ~] #
Command type:
Built-in commands (shell built-in), internal and built-in (when a command prompt is prompted after Logon: #, $, etc., then we enter a shell, shell is also an application, therefore, it also provides self-recognition commands for users: No need to configure environment variables)
[Root @ localhost ~] # Type cd
Cd is a shell builtin: shell built-in command
External command: an executable file corresponding to the command name under a path of the file system
[Root @ localhost ~] # Type su
Su is/bin/su
Environment variable: named memory space
Variable assignment
NAME = Jerry
PATH: PATH separated by a colon
O (1): A standard used to measure the execution speed of a program. The hash O (1) is so fast that the query cache is saved to the cache.
Hash: the number of times that commands have been executed in the cache and saved to the cache (key-value pairs exist in the hash)
[Root @ localhost ~] # Hash
Hits command
14/bin/ls
6/usr/bin/clear
-- Linux02_02? Operating System and Common commands
Type: display the specified type
Date: Time Management
Linux: rtc
Hardware clock: The Clock maintained by a hardware-level Oscillator
[Root @ localhost ~] # Hwclock
Wed 28 Jan 2015 07:25:47 pm pst-0.764336 seconds
[Root @ localhost ~] #
System clock: the system time maintained by the Linux kernel. There is an error because of cpu execution problems.
[Root @ localhost ~] # Date
Weds Jan 28 19:20:35 PST 2015
Get Command help:
Internal command:
Help COMMAND
External commands:
COMMAND -- help
Common query method --> command manual: manual. Since the manual must be a file and a compressed file
Man COMMAND: displays COMMAND Information:
1. Is it in the built-in shell?
2. Name
3. Syntax
4. Optional parameters
[Root @ localhost ~] # Man cd
BASH_BUILTINS (1)
BASH_BUILTINS (1)
NAME...
[Root @ localhost ~] # Man ls
LS (1) -- indicates the ls command User Commands LS (1) in the first section)
NAME
Ls-list directory contents
SYNOPSIS
Ls [OPTION]... [FILE]...
DESCRIPTION
Whatis COMMAND: displays the chapters of a COMMAND.
[Root @ localhost ~] # Whatis ls
Ls (1)-list directory contents
Ls (1 p)-list directory contents
[Root @ localhost ~] #
You can specify the chapters to search:
[Root @ localhost ~] # Man 1 ls
Man:
1: USER command (/bin,/usr/bin,/usr/local/bin): used by common users
2: System Call
3: database users
4: Special files (device files)
5: File Format (Configuration File Syntax): the syntax of the configuration file corresponding to a command
6: Games
7: Miscellaneous (Miscellaneous)
8: management commands (/sbin,/usr/sbin,/usr/local/sbin): Can Be Used by administrators
<>: Required.
[]: Optional
...: Can appear multiple times
|: Select one more
{}: Group
MAN:
NAME: command NAME and function description
SYNOPSIS: usage instructions, including available options
DESCRIPTION: A detailed DESCRIPTION of the command function, which may include the meaning of each option.
OPTIONS: Meaning of each option
FILES: configuration file related to this command
BUGS: WHO reports the bug?
EXAMPLES: Example
See also: For more information, SEE
Screen flip:
Flip back: SPACE
One screen forward: B
Flip One Line Backward: ENTER
One row forward: k
Search:
/KEYWORD: backward
N: Next
N: Previous
? KEYWORD: Forward
N: Next
N: Previous
Q: Exit
Online Documentation:
Info COMMAND
Document:/usr/share/doc
Google
Apache and hadoop
Exercise:
Use date to obtain the current year, month, day, hour, minute, and second of the system.
Hwclock
-W: synchronize system time to hardware
-S: Read the hardware time to the System
Date and hwclock usage:
[Root @ localhost ~] # Date 01282020.00 -- modification time
Weds Jan 28 20:20:00 PST 2015
[Root @ localhost ~] # Date + "date is % D" -- print time
Date is 01/28/15
[Root @ localhost ~] #
[Root @ localhost ~] # Hwclock-w
[Root @ localhost ~] # Hwclock
Wed Jan 28 20:22:39 2015-0.449991 seconds
[Root @ localhost ~] # Date
Weds Jan 28 20:22:45 PST 2015
[Root @ localhost ~] # Hwclock-s
Cal: calendar
[Root @ localhost yum-3.2.22] # cal 10 2014
October 1, 2014
Su Mo Tu We Th Fr Sa
1 2 3 4
5 6 7 8 9 10 11
12 13 14 15 16 17 18
19 20 21 22 23 24 25
26 27 28 29 30 31
Exercise:
1. Is echo an internal command or an external command?
[Root @ localhost yum-3.2.22] # type echo
Echo is a shell builtin
2. What is its role?
[Root @ localhost yum-3.2.22] # date + "today is % A % n date is % D"
Today is Wednesday
Date is 01/28/15
[Root @ localhost yum-3.2.22] # echo-e "today is Tu \ n date is 1/29" -- '-e' means start escape characters
Today is Tu
Date is 1/29
[Root @ localhost yum-3.2.22] # echo "today is Tu \ n date is 1/29"
Today is Tu \ n date is 1/29
[Root @ localhost yum-3.2.22] # echo-n "today is Tu \ n date is 1/29" -- remove line breaks
Today is Tu \ n date is 1/29 [root @ localhost yum-3.2.22] #
3. How do I display "The year is 2013. Today is 26." As two rows?
[Root @ localhost yum-3.2.22] # date + "today is % A % n date is % D"
Today is Wednesday
Date is 01/28/15
Escape means escape characters.
Exercise:
1. Is printf an internal command or an external command?
[Root @ localhost ~] # Type printf
Printf is a shell builtin
2. What is its role?
[Root @ localhost yum-3.2.22] # printf "today is Tu \ n date is 1/29 \ n"
Today is Tu
Date is 1/29
[Root @ localhost yum-3.2.22] # printf "today is Tu \ n date is 1/29"
Today is Tu
Date is 1/29 [root @ localhost yum-3.2.22] #
Therefore, the difference between printf and echo is that the previous line breaks by default.
3. How do I display "The year is 2013. Today is 26." As two rows?
-- Linux02_03? Operating System and Common commands File command and its usage.
[Root @ localhost ~] # File-I.
.: Application/x-not-regular-file
[Root @ localhost ~] # File-s.
.: Directory
[Root @ localhost ~] # File
Usage: file [-bcikLhnNsvz] [-f namefile] [-F separator] [-m magicfiles] file...
File-C-m magicfiles
Try 'file -- help' for more information.
[Root @ localhost ~] # File/dev/hdc
/Dev/hdc: block special (22/0)
[Root @ localhost ~] # File-s/dev/hdc
/Dev/hdc: ISO 9660 CD-ROM filesystem data 'rhel/5.5 x86_64 DVD '(bootable)
[Root @ localhost ~] #
Windows: PE
Linux: ELF
File System: partition-based, but all partition file systems must be under the root file
Rootfs: root file system
FHS: Directory standards that Linux complies with (file system level standards)
/Boot: files related to system startup, such as kernel, initrd, and grub (bootloader)
[Root @ localhost ~] # Ls/boot/
Config-2.6.18-194.el5 symvers-2.6.18-194.el5.gz
Grub System. map-2.6.18-194.el5
Initrd-2.6.18-194.el5.img vmlinuz-2.6.18-194.el5
Lost + found
(Everything in Linux is a file, and the device is also a file, the portal)
/Dev: Device File
DEVICE file:
Block devices: Random Access, data blocks
Character device: Linear access, in characters
Device No.: main device No. (major) and sub-device No. (minor ):
Crw-rw ---- 1 root tty 4, 37 Jan 28 tty37
/Etc: Configuration File
/Home: the home directory of a user. The default home directory of each user is/home/USERNAME.
/Root: Administrator's home directory;
You cannot log on to the production environment by using the root user, because it has the most permissions and can easily delete files by mistake.
/Lib: library file (which has been written and can be called directly)
/Lib/modules: kernel module File
Static library,.
[Root @ localhost lib] # file libdevmapper.
Libdevmapper. a: symbolic link to 'libdevmapper. a.1.02'
Dynamic library,. dll (in window),. so (shared object)
[Root @ localhost lib] # file libc-2.5.so
Libc-2.5.so: ELF 32-bit LSB shared object, Intel 80386, version 1 (SYSV), for GNU/Linux 2.6.9, not stripped
[Root @ localhost lib] #
Dynamic and Static differences:
Static libraries are compiled together with library files during static compilation, so during migration
It must be transplanted together with the library.
A dynamic library is also called a shared library, that is, multiple programs are compiled and shared at a time.
Why are the following two files executable, but the first one is not executable?
[Root @ localhost lib] # file libc-2.5.so
Libc-2.5.so: ELF 32-bit LSB shared object, Intel 80386, version 1 (SYSV), for GNU/Linux 2.6.9, not stripped
[Root @ localhost lib] # file/bin/ls
/Bin/ls: ELF 64-bit LSB executable, AMD x86-64, version 1 (SYSV), for GNU/Linux 2.6.9, dynamically linked (uses shared libs ), for GNU/Linux 2.6.9, stripped
[Root @ localhost lib] #
Because: The above is the library file, the library file is not executed independently, it can only be called
/Lost + found: used to save special circumstances such as sudden power failure, used to save files for fear of loss
/Media: mount point directory, mobile device
/Mnt: mount point directory, additional temporary file system
Mount point: the point where the device is mounted to a directory in the file system.
Hanging Process: A device must be loaded to a directory of the current file system for access.
This process is the mounting process.
/Opt: optional Directory. The installation directory of third-party programs is now in/usr/local
/Proc: pseudo file system, kernel ing File
/Sys: pseudo file system, property ing file related to hardware devices
/Tmp: temporary file,/var/tmp
/Var: changeable File
The following two executable files and commands must be executed by the system before it is started.
/Bin: executable file, USER command
/Sbin: Management command
/Usr: shared, read-only
The following are the executable files and commands provided to improve other functions of the system after the system is started:
/Usr/bin
/Usr/sbin
/Usr/lib
/Usr/local: installation path for third-party software, non-critical Program
/Usr/local/bin
/Usr/local/sbin
/Usr/local/lib
Naming rules:
1. The length cannot exceed 255 characters;
2. Cannot Use/when the file name
3. Case Sensitive
Relative Path:
Absolute path:
File Management
Directory management
Ls
Cd
Pwd
Mkdir: Create an empty directory
-P: If the created parent directory does not exist, create the parent directory first.
-V: verbose displays execution details
/Root/x/y/z
/Mnt/test/x/m, y
Mkdir-pv/mnt/test/x/m/mnt/test/y
Mkdir-pv/mnt/test/{x/m, y}
~ USERNAME
Expand the command line:
/Mnt/test2/
A_ B, a_c, d_ B, d_c
(A + d) (B + c) = AB + ac + db + dc
{A, d }_{ B, c}
[Root @ localhost ~] # Mkdir-pv./test/{a, B }_{ c, d}
Mkdir: created directory './Test'
Mkdir: created directory './test/a_c'
Mkdir: created directory './test/a_d'
Mkdir: created directory './test/B _c'
Mkdir: created directory './test/B _d'
[Root @ localhost ~] # Mkdir./test/{a, B}/{c, d}
Mkdir: created directory '/test/'
Mkdir: created directory '/test/a/C'
Mkdir: created directory '/test/a/d'
Mkdir: created directory '/test/B'
Mkdir: created directory '/test/B/C'
Mkdir: created directory '/test/B/d'
# Tree: view the directory tree
Delete directory: rmdir (remove directory)
Delete empty directory
-P: Only one-pulse, single-pass directories can be deleted:
[Root @ localhost test] # mkdir-p x/y/z
[Root @ localhost test] # tree
.
| -- A_c
| -- A_d
| -- B _c
| -- B _d
'-- X
'-- Y
'-- Z
7 directories, 0 files
[Root @ localhost test] # rmdir-p x/y/z
[Root @ localhost test] # tree
.
| -- A_c
| -- A_d
| -- B _c
'-- B _d
4 directories, 0 files
File Creation and Deletion
Files or directories with the same name cannot exist. This is also true in windows, but the file format is hidden by the system.
# Touch: Modify the file Timestamp
-A: Change the access time
-M: Change the modification time.
-T: specifies the time
-C: create a file
[Root @ localhost ~] # Stat test/
File: 'test /'
Size: 4096 Blocks: 8 IO Block: 4096 directory
Device: 802 h/2050d Inode: 852122 Links: 6
Access: (0755/drwxr-xr-x) Uid: (0/root) Gid: (0/root)
Access: 23:55:59. 000000000-0800
Modify: 23:55:59. 000000000-0800
Change: 23:55:59. 000000000-0800
[Root @ localhost ~] # Date
Weds Jan 28 23:56:12 PST 2015
[Root @ localhost ~] # Touch-m-t 201212121212 test/
[Root @ localhost ~] # Stat test/
File: 'test /'
Size: 4096 Blocks: 8 IO Block: 4096 directory
Device: 802 h/2050d Inode: 852122 Links: 6
Access: (0755/drwxr-xr-x) Uid: (0/root) Gid: (0/root)
Access: 23:55:59. 000000000-0800
Modify: 12:12:00. 000000000-0800
Change: 23:57:24. 000000000-0800
[Root @ localhost ~] # Touch-a test/
[Root @ localhost ~] # Stat test/
File: 'test /'
Size: 4096 Blocks: 8 IO Block: 4096 directory
Device: 802 h/2050d Inode: 852122 Links: 6
Access: (0755/drwxr-xr-x) Uid: (0/root) Gid: (0/root)
Access: 23:58:19. 000000000-0800
Modify: 12:12:00. 000000000-0800
Change: 23:58:19. 000000000-0800
[Root @ localhost ~] #
# Stat
Create a file. You can use the file editor.
ASCII:
128 different characters:
Binary:
2 ^ 6 = 0, 63
2 ^ 7 = 0,127
000 0000-111 1111
ASCII:
0000 1001: t
2 ^ 16: 65536
Standard: GB18030, GBK, GB2312, Unicode
0000 1001 0000 1110: Shang, Wei
Nano: Text Editor
Delete file: rm
-I
-F
-R
Rm-rf/
[Root @ localhost ~] # Type rm
Rm is aliased to 'rm-I '--> indicates that rm is an alias: rm-I
[Root @ localhost ~] # Rm-I te
Rm: remove regular empty file 'te '? Y
[Root @ localhost ~] # Touch te1 te2
[Root @ localhost ~] # Ls
C Desktop Unix exit install. log te1 test
DOS Solaris anaconda-ks.cfg grant install. log. syslog te2 vms
[Root @ localhost ~] # \ Ls
C Desktop Unix exit install. log te1 test
DOS Solaris anaconda-ks.cfg grant install. log. syslog te2 vms
[Root @ localhost ~] # Type ls
Ls is aliased to 'ls -- color = tty '--> is also an alias command, indicating that the corresponding file is colored. This alias command is not available to common users.
[Root @ localhost ~] # Rm-rf test --> delete a recursive file and force it to be deleted
[Root @ localhost ~] #
-- Linux02_04? Operating System and Common commands Exercise:
1. Create a directory
(1) Create boot and sysroot under/mnt;
(2) create grub under/mnt/boot;
(3) create proc, sys, bin, sbin, lib, usr, var, etc, dev, home, root, tmp under/mnt/sysroot
A) Create bin, sbin, lib under/mnt/sysroot/usr
B) Create modules under/mnt/sysroot/lib
C) Create run, log, lock under/mnt/sysroot/var
D) Create init. d under/mnt/sysroot/etc.
Copy and move files
Cp: copy
The default value is cp-L, which indicates the file to which the default copy link points.
Cp SRC (multiple) DEST (only one)
-R: recursive
-I: Interactive
-F: forcible
-D: copy the link
[Root @ localhost ~] # Cp-d/etc/rc test_cp/test
[Root @ localhost ~] # Ls-l test_cp/
Total 0
Lrwxrwxrwx 1 root 7 Jan 29 0:27 test-> rc. d/rc
[Root @ localhost ~] #
-P: reserved group-p same as -- preserve = mode, ownership, timestamps
-A: Archive replication, usually used for backup
-A, -- archive
Same as-dR -- preserve = all
-D same as -- no-dereference -- preserve = link
-P, -- no-dereference never follow symbolic links: Indicates copying a link without copying the file to which the link is directed.
-- Preserve = link: Save the link
-- Preserve = all: Keep all attributes of the Group
-R: recursive
[Root @ localhost test_cp] # cp/etc/init. d/test1
Cp: omitting directory '/etc/init. d /'
[Root @ localhost test_cp] # cp-r/etc/init. d/test1 --> The above indicates that the copy directory must be recursive.
[Root @ localhost test_cp] # cp/etc/init. d/acpid/etc/init. d/atd test1 --> rename the copied file name
Cp: overwrite 'test1/acpid '? N
Cp: overwrite 'test1/atd '? N
[Root @ localhost test_cp] # cp/etc/init. d/acpid/etc/init. d/atd test2 --> if multiple files are copied, the target must be a directory.
Cp: target 'test2' is not a directory
Cp file1 file2 file3
One file to one file
Multiple files to one directory
Cp/etc/{passwd, inittab, rc. d/rc. sysinit}/tmp/
Mv: move
Move files
Mv SRC DEST
Mv-t DEST SRC
[Root @ localhost test_cp] # mv test2/installActions2014-12-20_09-55-25PM.log ../test_cp/
[Root @ localhost test_cp] # ls
InstallActions2014-12-20_09-55-25PM.log (test2)
[Root @ localhost test_cp] # Music installActions2014-12-20_09-55-25PM.log installActions --> rename
[Root @ localhost test_cp] # ls
InstallActions test2
[Root @ localhost test_cp] # mv test2/installActions --> A directory cannot be used to overwrite a file.
Mv: cannot overwrite non-directory 'installactions' with directory 'test2 /'
[Root @ localhost test_cp] # mv ora installActions --> overwrite the file, but there is no overwrite between Directories
Mv: overwrite 'installactions '? Y
[Root @ localhost test_cp] #
Install
-D DIRECOTRY...: create a directory
SRC (file, cannot be a directory) DEST
Install-t directory src... (file, cannot be a DIRECTORY)
[Root @ localhost test_cp] # install-d dir --> creating a directory is equivalent to mkdir
[Root @ localhost test_cp] # ls
Dir installActions test2 [root @ localhost test_cp] # install dir/test2/--> install does not have a copy directory
Install: omitting directory 'dir /'
[Root @ localhost test_cp] # install installActions test2/
[Root @ localhost test_cp] # ls-l test2/
Total 4
-Rwxr-xr-x 1 root 0 Jan 29 installActions --> the default copy file is rwxr-xr-x
-Rw-r ----- 1 root 117 Jan 29 oraInstall2014-12-20_09-55-25PM.out
[Root @ localhost test_cp] # install-o oracle-m-rw test2/oraInstall2014-12-20_09-55-25PM.out ./
[Root @ localhost test_cp] # ls-l
Total 12
Drwxr-xr-x 2 root 4096 Jan 29 06:15 dir
-Rw-r ----- 1 root 0 Jan 29 0:42 installActions
---------- 1 oracle root 117 Jan 29 oraInstall2014-12-20_09-55-25PM.out
Drwxr-x --- 2 root 4096 Jan 29 test2
[Root @ localhost test_cp] #
