Second week Linux micro jobs

1. What are the file management commands on Linux, their commonly used methods and their related examples?

For:

File Management:

CP, MV, RM

Copy command: CP

CP [OPTION] ... [-T] SOURCE DEST

CP [OPTION] ... SOURCE ... DIRECTORY

CP [OPTION] ...-t DIRECTORY SOURCE ...

CP SRC DEST

SRC is a file:

If the target does not exist: Creates a new dest and fills the contents of SRC into the dest;

If the directory exists:

If Dest is a file: overwrites the contents of SRC into the dest;

It is recommended to use the-I option for the CP command;

If Dest is a directory: Create a new file with the same name as the original file under Dest, and populate the contents of SRC with the new file;

CP SRC ... DEST

Src... : Multiple Files

Dest must exist and be directory, other situations will be error;

CP SRC DEST

SRC is the directory:

Use option at this time:-R

If Dest does not exist: creates the specified directory and copies all files in the SRC directory to dest;

If dest exists:

If Dest is a file: Error

If Dest is a directory:

Common options:

-I: Interactive

-R,-r: recursively copy directories and all internal content;

-A: Archive, equivalent to-DR--preserv=all

-d:--no-dereference--preserv=links

--preserv[=attr_list]

Mode: Permissions

Ownership: Belong to the main group

Timestamp

Links

Xattr

Context

All

-P:--preserv=mode,ownership,timestamp

-V:--verbose

-F:--force

Mv:move, moving files

MV [OPTION] ... [-T] SOURCE DEST

MV [OPTION] ... SOURCE ... DIRECTORY

MV [OPTION] ...-t DIRECTORY SOURCE ...

Common options:

-I: Interactive

-F: Mandatory

Rm:remove, deleting

RM [OPTION] ... FILE ...

Common options:

-I: Interactive

-F: Force delete

-R: Recursive

Rm-rf

Text Editor: Nano

Full Screen Editor

2. Bash's work characteristics the command execution status return value and command line expansion are involved in the content and its sample demonstration. Command line expansion

~: Expand to the user's home directory

~username: Expand the home directory for the specified user

{}: Can host a comma-delimited list and expand it to multiple paths

/tmp/{a,b} =/tmp/a,/tmp/b

/tmp/{tom,jerry}/hi =/tmp/tom/hi,/tmp/jerry/hi

(5) Execution result status of the command

Success

Failed

Bash uses a special variable $? Save the execution status result of the most recent command:

0: Success

1-255: Failure

Program execution has two types of results:

The return value of the program;

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3. Use the command line expansion function to complete the following exercises:

(1), create/tmp directory: A_c, A_d, B_c, B_d

(2), create the/tmp/mylinux directory:

mylinux/

├──bin

├──boot

│└──grub

├──dev

├──etc

│├──rc.d

││└──init.d

│└──sysconfig

│└──network-scripts

├──lib

│└──modules

├──lib64

├──proc

├──sbin

├──sys

├──tmp

├──usr

│└──local

│├──bin

│└──sbin

└──var

├──lock

├──log

└──run

Answer: (1)

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(2):

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4, what is the metadata information of the file, what does it mean, how to view it? How to modify timestamp information for a file.

For:

. Three timestamps:

Access time: Atime, read and write file contents

Modify Time: Modified, Mtime, change file contents (data)

Change time: Changing times, ctime, meta data changes

Time stamp for modified file: Touch

Touch [OPTION] ... FILE ...

-a:only Atime

-m:only Mtime

-S STAMP:

[[Cc]yy] MMDDHHMM[.SS]

-C: If the file does not exist, it is not created

5, how to define the alias of a command, how to reference the execution result of another command in the command?

A: Define an alias for a command, for example: Alias die = ' Rm-rf '

Setting an alias for an instruction

Syntax: # alias name= ' command line '

Parameters:
-P: Print the aliases that appear (unique parameters)
If no parameters are added, all current alias settings are listed

Usage:
# alias cp= ' Cp-i ' or alias l= ' ll ';

The command is Ficonfig eth0, and the variable is IP:
#!/bin/bash
ip= ' ifconfig eth0 '
Echo $ip
This assigns the command generated string to the IP, Echo $ip, see the result of the command execution

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Second week Linux micro jobs