Shulou(Shulou.com)06/02 Report--

Linux Command File Management user Management

1. Linux command

Command syntax general format # COMMAND OPTION ARGUMENTS1, the meaning of the command: initiate a command: request the kernel to run a binary program as a process; the command is an executable binary program file that may call a shared file library. [root@localhost tmp] # file / bin/ls-View ls file types / bin/ls: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.32, BuildID [sha1] = 0xec333a104e045327c5e3d0ca6dda16c610a210f3, stripped programs-- > process static-- > dynamic (lifecycle) file files: query file type information Ldd: you can view a shared library on which an executable program depends [root@localhost tmp] # ldd / bin/lslinux-vdso.so.1 = > (0x00007fffb81fe000) libselinux.so.1 = > / lib64/libselinux.so.1 (0x00007f7882e89000) libcap.so.2 = > / lib64/libcap.so.2 (0x00007f7882c84000) libacl.so.1 = > / lib64/libacl.so.1 (0x00007f7882a7a000) libc.so.6 = > / lib64/libc.so.6 (0x00007f78826b9000) libpcre.so.1 = > / lib64/libpcre.so.1 (0x00007f7882458000) libdl.so.2 = > / lib64/libdl.so .2 (0x00007f7882253000) / lib64/ld-linux-x86-64.so.2 (0x00007f78830c3000) libattr.so.1 = > / lib64/libattr.so.1 (0x00007f788204e000) libpthread.so.0 = > / lib64/libpthread.so.0 (0x00007f7881e32000) Library: existing ones written by others Mature, reusable code that can be used but subject to a license agreement Static libraries are suffixed with .a; dynamic libraries (shared libraries) are suffixed with .so, which is compiled by gcc with specific parameters.

How do I locate shared library files? How to make the system recognize after installing a new library? How do I create static and dynamic libraries in Linux and use them?

For details, please refer to: https://www.cnblogs.com/yangg518/p/5842651.html

2. System program storage path: / bin; / sbin; / usr/bin; / usr/sbin; / usr/local/bin; / usr/local/sbin; Common command: / bin; / usr/bin; / usr/local/bin; Management name: / sbin; / usr/sbin; / usr/local/sbin; shared library file: / lib;/ lib64; / usr/lib;/usr/lib64; / usr/local/lib / usr/local/lib64; Note: not all commands have an executable file corresponding to it in a directory.

3. The category of the command: it is distinguished by whether there is an executable file.

View the type and location of commands: type COMMAND built-in commands: commands included in shell programs; builtin [root@localhost bin] # type printf printf is a shell builtin external commands: stand-alone executable program files, that is, commands: [root@localhost bin] # type zip zip is / bin/zip

4 、 shell

The shell program is a unique program that parses commands provided by users.

Environment variable: PATH

[root@localhost bin] # echo $PATH/usr/java/jdk1.6.0_45/bin:/bin:/usr/bin:/root/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin

PATH: find the command file corresponding to the command string typed by the user from the path: from left to right, until the command is found for the first time. OPTIONS: two forms of expression: short options, such as-l-d (note that some options do not have -), merging, such as-ld; long options, such as-- word; cannot be merged ARGUMENTS: the object to which the command functions. The effective part can take multiple parameters, separated by white space characters. Such as [root@localhost bin] # ls / tmp / etc/ssh/etc/ssh:moduli ssh_host_ecdsa_key ssh_host_ed25519_key.pubssh_config ssh_host_ecdsa_key.pub ssh_host_rsa_keysshd_config ssh_host_ed25519_key ssh_host_rsa_key.pub/tmp:2004-02-29 16:21:42 script2017-02-29 16:21:42 sort.txt2017-4-5 systemd-private-1f0c154d3be34ae4bc6670cd76168c21-colord. Service-NOKmzLcat systemd-private-1f0c154d3be34ae4bc6670cd76168c21-rtkit-daemon.service-ekYjoAfatabmy vmware-rootfunctions yum_save_tx.2019-06-24.08-11.VV74Ze.yumtxglfstab yum_save_tx.2019-06-25.16-52.9YerbK.yumtxmagedu.com syntax format: angle brackets

: required parameter, should be replaced with required parameter curly braces {}: required parameter, internal use, including the parameter square braces allowed here []: optional parameter, choose parentheses in the command as needed (): specify the default value of the parameter, only used for the vertical bar in {} |: a | b | C; used to separate multiple mutually exclusive parameters, meaning "or". You can only select one when using it. Ellipsis.: any number of parameters.

5. Get command help

Built-in commands: help COMMAND all commands: 1) Command comes with help in brief format # COMMAND-- help [root@localhost bin] # mke2fs-- helpmke2fs: invalid option--'- 'Usage: mke2fs [- c |-l filename] [- b block-size] [- C cluster-size] [- I bytes-per-inode] [- I inode-size] [- J journal-options] [- G flex-group-size] ] [- N number-of-inodes] [- m reserved-blocks-percentage] [- o creator-os] [- g blocks-per-group] [- L volume-label] [- M last-mounted-directory] [- O feature [ [- r fs-revision] [- E extended-option [,...]] [- t fs-type] [- T usage-type] [- U UUID] [- jnqvDFKSV] device [blocks-count]

2) Manual query help: manual COMMAND or man COMMAND manual is located at: / usr/share/man-requires a manual for compressed format files, which can be divided into chapters CHAPTER: man1; man2; man3. 1: user command 2: system call 3: C library call 4: device file and special file 5: file format (configuration file format) 6: game use help; 7: miscellaneous 8: management tools and daemons; system administrator manual. # whatis COMMAND-which CHAPTER manual is there for the query command # man CHAPTER COMMAND-specify the manual for querying CHAPTER;-M / PATH/-- go to the specified directory to find the manual

[root@localhost bin] # whatis passwdsslpasswd (1ssl)-compute password hashespasswd (1)-update user's authentication tokenspasswd (5)-password file [root@localhost bin] # man 5 passwdPASSWD (5) Linux Programmer's Manual PASSWD (5) NAMEpasswd-password file manually update man's database: # makewhatis # info COMMAND View the info help documentation for this command the application comes with documentation: / usr/share/doc/APP-VERSIONgoogle search query: keyword filetype: pdf specifies the document type Keyword site:domain specifies a website

6. Command alias

External commands can be aliased, can be the same as the original name, if the same, the original name is hidden. [root@localhost dev] # type ls ls is aliased to `ls-- color=auto'-ls is the alias of ls-- color=auto [root@localhost dev] # alias-query alias alias cp='cp-i'alias egrep='egrep-- color=auto'alias fgrep='fgrep-- color=auto'alias grep='grep-- color=auto'alias l.='ls-d. *-- color=auto'alias ll='ls-l-- color=auto'alias ls='ls- -color=auto'alias mv='mv-i'alias rm='rm-i'alias which='alias | / usr/bin/which-- tty-only-- read-alias-- show-dot-- show-tilde' [root@localhost dev] # unalias ls-revoke alias [root@localhost dev] # aliasalias cp='cp-i'alias egrep='egrep-- color=auto'alias fgrep='fgrep-- color=auto'alias grep='grep-- color=auto'alias l.='ls-d. *-- color=auto 'alias ll='ls-l-- color=auto'alias mv='mv-i'alias rm='rm-i'alias which='alias | / usr/bin/which-- tty-only-- read-alias-- show-dot-- show-tilde' [root@localhost dev] # type ls-see that ls is an external command Ls is hashed (/ bin/ls) [root@localhost dev] # alias ls='ls-- color=auto'-add back the original command to execute the alias, using\ COMMAND The alias setting is valid for the current shell

7. Common commands

Pwd: current directory cd: cd or cd ~ switch to home directory cd-switching to the previous directory implies two variables: $PWD; $OLDPWD [root@localhost tmp] # echo $PWD/tmp [root@localhost tmp] # echo $OLDPWD/bin [root@localhost tmp] # cd-/ bin [root@localhost bin] # cd-/ tmp

Ls:ls [OPTION]... [FILE]...

-l

Such as:

-rw-r--r--. 1 root root 18281 Jun 4 06:08 functions

File type: -; d; b; c; l; s; p

-rw-rwxr--: permission

Left: user; host

Middle: group hostel group

Right: other other users

18281: bytes; (note that the size of the directory does not represent the sum of all the files at its next level, on behalf of itself)

4: number of hard connections

-h file size conversion

-d check the directory itself

[root@localhost tmp] # ls-ld / tmp

Drwxrwxrwt. 13 root root 4096 Jul 7 01:29 / tmp

-r reverse order display

-R recursively shows all

Cat: view text files (look at binary files, a bunch of random codes)

Cat [OPTION]... [FILE]...

-n: line number display

-E: show Terminator

Reverse order of tac:cat

File: viewing file typ

Echo:

Echo [SHORT-OPTION]... [STRING]...

-e displays escape characters\ nnewline\ t tabs

STING uses single and double quotation marks

Single quotation marks: strong reference variable reference does not perform substitution

Double quotation marks: weak reference variable references will be replaced

Wall: sending messages

Date command:

Date

Display system time

+ FORMAT

+ F; full date; same as Y-%m-%d

+% T: time; same as% H:%M:%S

+% S: seconds since 1970-01-01 00:00:00 UTC

: (hyphen) do not pad the field

[root@localhost script] # dateSun Jul 7 02:00:35 PDT 2019 [root@localhost script] # date +% F2019-07-07 [root@localhost script] # date +% T02 purge 05PDT 31 [root@localhost script] # date +% s1562490341

Set system time

Date [MMDDhhmm [[CC] YY] [.ss]

The Linux system starts to read the time and date from the hardware, and when the read is complete, the date time is no longer associated with the hardware item.

System clock:

Hardware clock:

Hwclock: query or set the hardware clock displays or sets the hardware clock

-s: Set the System Time from the Hardware Clock hard prevails

-w: Set the Hardware Clock to the current System Time system shall prevail

Cal; display a calendar

Cal [options] [day] month] year]

Exercise: create a file under the / tmp directory that starts with tfile, followed by the current date and time, with a name such as: tfile-2016-05-27-09-32-22.

[root@localhost mk] # echo "tfile-/date"-Command date not executed Quote the command result to $(COMMAND) tfile-/date [root@localhost mk] # echo "tfile-$ (date)"-date format to deal with tfile-Sun Jul 7 07:24:53 PDT 2019 [root@localhost mk] # echo "tfile-$ (date +% F-+%H-+%M-+%S)"-this + one is enough for tfile-2019-07-07 Mustang "25 Mustang" 45 [root @ localhost mk] # echo "tfile-$ (date +% F-%H-%M-%S)"-the result is coming up tfile-2019-07-07-07-25-59 [root@localhost mk] # touch "tfile-$ (date +% F-%H-%M-%S)" [root@localhost mk] # lsmydir tfile-2019-07-07-07-26-18

II. Document management

1. File type

-regular file, i.e. file

D directory file

B block device is a block device file, such as a hard disk, which supports random access in units of block

C character device is a character device file. For example, the keyboard supports linear access in character units.

Major number: the main device number, used to identify the device type and load the driver

Minor number: a secondary number used to identify different devices of the same device type.

[root@localhost dev] # ls-l / dev | grep sdabrw-rw----. 1 root disk 8, 0 Jul 3 07:14 sdabrw-rw----. 1 root disk 8, 1 Jul 3 07:14 sda1brw-rw----. 1 root disk 8, 2 Jul 3 07:14 sda2brw-rw----. 1 root disk 8, 3 Jul 3 07:14 sda3

L symbolic link is a symbolic link file, also known as a soft link file

P pipe is named pipe file

S socket is a socket file, which is used to implement the communication between two processes-this socket was very familiar with writing TCP communication programs at the time, but now I forgot all about it!

2. Common commands

Mkdir: make directories create directory

-p: automatically create a parent directory

[root@localhost tmp] # mkdir / tmp/mk/mydirmkdir: cannot create directory'/ tmp/mk/mydir': No such file or directory [root@localhost tmp] # mkdir-p / tmp/mk/mydir-created successfully

-v: verbose shows the creation process

-m: set permissions

Rmdir: remove empty directories delete directory

-P: delete a directory, if the parent is empty, delete it as well; rmdir-p _ a _ is similar to _

Tree: display directory hierarchy

-L level displays specified layer groups, such as tree-L 3

Exercise:

1) create / tmp/a1, / tmp/a2, / tmp/a1/a, / tmp/a1/b.

Using {} grouping, you can carry a list of paths divided by commas

[root@localhost mk] # mkdir / tmp/a {1 {root@localhost tmp b}, 2} [root@localhost mk] # cd / tmp/ [root@localhost tmp] # tree ├── A1a ├── A1b ├── a2 [root@localhost tmp] # mkdir-pv / tmp/a {1 / {aForce b}, 2}-r without p Then display mkdir:cannotcreate directory'/ tmp/a1/a': No such file or directormkdir: created directory'/ tmp/a1'mkdir: created directory'/ tmp/a1/a'mkdir: created directory'/ tmp/a1/b'mkdir: created directory'/ tmp/a2

2) create a directory under the / tmp directory: xSecrety, xfantz, qroomy, qroomz

[root@localhost tmp] # mkdir-pv / tmp/ {XMagne Q} / {YMagne z} mkdir: created directory'/ tmp/x'mkdir: created directory'/ tmp/x/y'mkdir: created directory'/ tmp/x/z'mkdir: created directory'/ tmp/q'mkdir: created directory'/ tmp/q/y'mkdir: created directory'/ tmp/q/z' [root@localhost tmp] # mkdir-pv / tmp/ {xMagne Q} _ {y Z} mkdir: created directory'/ tmp/x_y'mkdir: created directory'/ tmp/x_z'mkdir: created directory'/ tmp/q_y'mkdir: created directory'/ tmp/q_z'

3. Data information and query of documents

File viewing tool:

Cat;tac; less; more; head; tail

Tail:-output the last part of files displays n lines at the end of the file. The default is 10 lines.

Tail-20 somefile

-f: output appended data as the file grows;-typically used to track logs converted to background applications

The file contains two types of data: metadata + body actual data

Metadata Metadata: the data that describes the data, that is, data property information

Such as size, permissions, host group, timestamp, block distribution information (inode), etc.

Timestamp:

Access time: time when the ATime data was last read

Modify time: when the MTime data was last changed

(when the actual data changes, reading does not necessarily occur! , such as redirect > > input)

Change time: when the CTime metadata was last changed

(if the actual data changes, this will certainly change, but if you use touch to modify the data stamp, it will not change.)

View file data information: stat file

[root@localhost tmp] # stat glfstab File: 'glfstab'Size: 0 Blocks: 0 IO Block: 4096 regular empty fileDevice: 803h/2051d Inode: 103529576 Links: 1Access: (0644 Mae RW Mustang Rafael Rafael -) Uid: (1002 / user1) Gid: (1002 / user1) Context: unconfined_u:object_r:user_tmp_t:s0Access: 2019-06-23 06 Vav 3V 129.863083244-0700Modify : 2019-06-23 0631 Birth 29.863083244-0700Change: 2019-06-230840 Birth:-

Modify the information of the file timestamp:

Touch [OPTION]... FILE... Change the timestamp. By default, CTime cannot specify a replacement. If the file does not exist, a file will be created.

-an ATime

-m MTime

Human readable date string such as "Sun, 29 Feb2004 16:21:42-0800" or "2004-02-29 16:21:42" or

Even "next Thursday"

-c CTime do not create any files

-t specified time; [[CC] YY] MMDDhhmm [.ss]

[root@localhost tmp] # touch-t 201707070707 glfstab [root@localhost tmp] # stat glfstab File: 'glfstab'Size: 0 Blocks: 0 IO Block: 4096 regular empty fileDevice: 803h/2051d Inode: 103529576 Links: 1Access: (0674Mae RWXR 1Access -) Uid: (1002 / user1) Gid: (1002 / user1) Context: unconfined_u:object_r:user_tmp_t:s0Access: 2017-07-0707: 07 RWXR: 00.000000000 -0700Modify: 2017-07-07 Birth 07 Birth: 07-07-07 Birth 07-0000000000-0700Change: 2019-07-06 2238 Birth:-[root@localhost tmp] # echo "be a test" > > glfstab (modified with vim) Atime is bound to change with MTime Use > > ATim unchanged) [root@localhost tmp] # stat glfstab File: 'glfstab'Size: 28 Blocks: 8 IO Block: 4096 regular fileDevice: 803h/2051d Inode: 103529576 Links: 1Access: (0674 Maxim RWRWXRML -) Uid: (1002 / user1) Gid: (1002 / user1) Context: unconfined_u:object_r:user_tmp_t:s0Access: 2019-07-06 2240 Uid 43.228353962-0700Modify: 2019-07-06 22 42 30.142275224-0700Change: 2019-07-06 22 22 22 purl 30.142275224-0700 Birth:-

4. File management tool

Cp:

Single-> single (renamed)-is usually used to back up files

Multiple (use {})-> directory

-I: interaction

-n: do not overwrite an existing file

-f: forced replication without asking for coverage replication

-R-r: recursively copy directory

Mv: move (rename) files-you said that this thing broke down in the middle of the copy. How to restore the contents on both sides of the directory?

Ctrl+c ctrl+V is more secure than direct ctrl+X.

-b: like-- backup but does not accept an argument-- this is also safe

Rm:remove files or directories-dangerous action, or first mv to the temporary folder, after a period of time in the temporary folder rm security

-I: interaction

-f: force

-R-r: recursive; recursive deletion

Delete the directory rm-rf

Serious warning:

Enter this command under the authority of root, it is very easy to rm-rf / operation, all gone, so finally restrict it or use an alias.

Root permissions are dangerous, rm is dangerous, and the combination of the two is dangerous.

Exercise: copy all files or directories under the / etc directory that begin with p and end with non-numbers into the / tmp/mytest1 directory.

[root@localhost tmp] # cp-rv / etc/ [p] * [^ [[: digit:] / tmpcp: cannot stat'/ etc/ [p] * [^ [[: digit:]': No such file or directory [root@localhost tmp] # cp-rv / etc/ [p] * [^ [: digit:]] / tmp'/ etc/pam.d'->'/ tmp/pam.d''/etc/pam.d/config-util' ->'/ tmp/pam.d/config-util''/etc/pam.d/other'->'/ tmp/pam.d/other''/etc/pam.d/chfn'->'/ tmp/pam.d/chfn''/etc/pam.d/chsh'->'/ tmp/pam.d/chsh

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