Detailed Linux file processing of the common commands __linux

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My 8 tips for using the shell

Nine classic usage scenarios for grep

SED command detailed

awk Command Detailed

Everything in Linux is a file, and the command is a binary file.

1, LS

/bin/ls

Common options

-A All files (including hidden files)

-L Detailed information

-D Directory Properties

-I view Inode

Example

[root@localhost testforcsdn]# ls
filelist-i  second
[root@localhost  testforcsdn]# ls-a ...  filelist  Second
[root@localhost testforcsdn]# ls-l Total
-rw-r--r--1 root root Oct 23:12 filelist
-rw-r--r--1 root   0 Oct 18:04 A-
1 root root   0 Oct 24 18:04 second
[root@localhost testforcsdn]# ls-al total drwxr-xr-x  2 root 4096 Oct 24 18:04. C20/>drwxr-x---root root 4096 Oct 17:56.
-rw-r--r--  1 root  Oct 23:12 filelist
-rw-r--r--  1 root    0 Oct 18:04 first
  
   -rw-r--r--  1 root    0 Oct 18:04 Second
[root@localhost testforcsdn]# ls-d
.
[Root@localhost testforcsdn]# ls-i
2256719 filelist  2256718-A-2256730  

  

Analysis under

-rw-r--r--1 root Oct 23:12 filelist

For this line, analyze from left to right

-Indicates that this is a binary file

rw-r--r--respectively R for Read permission, W for write permission,-to indicate that there is no permission, if X is an executable, a total of 9, three groups, respectively, representing the creator, the group, the others

Therefore, for the creator is rw-is read-write is not executable, for the owning group is r--only Read permission, others only Read permission

1 indicates the number of hard links

The first root represents a user

The second root represents the user group

100 indicates file size, if directory is directory and subdirectory size

OCT 18 23:13:12 Indicates the last modified time

FileList indicates file name

2, CD

Change direction

The usual commands for matching CDs and

PWD View current directory

Change Directory

First, explain the following directory

/root partition, all files and directories start from here

/bin users can execute files

/sbin system executable file, mainly for administrator use, s for super

/ETC configuration file

/dev Device files

/proc process information, such as/proc/cpuinfo containing processor information

/var variable files such as Log,mail

/USR user program, storing files for user applications

/home User Home Directory

/boot Start Add-ins

/opt Optional Application

/MNT Mount Directory

/media removable media such as/media/cdrom

/SRV Service Data

Example

[Root@localhost etc]# cd/etc/
[root@localhost etc]# pwd
/etc
[root@localhost etc]# cd ~
[ Root@localhost ~]# pwd
/root

What we're going to say here is,

CD ~ Represents the home directory of the current login user

If it's root back to/root/,

If it's a regular user, go back to/home/

3. Touch

Create a blank file file or modify the timestamp of a file

Common options

-A Change access time only

-C does not create any documents

-d Use the specified date

-M only change change time

-R Changes the date time of the specified document or directory to the same as the reference document

-T sets the time stamp specified

Example

[root@localhost testforcsdn]# ls-l Total
-rw-r--r--1 root Oct 23:12 filelist-rw-r--r--
1 roo T-root   0 Oct 18:04
-rw-r--r--1 root   0 Oct 18:04 Second
[Root@localhost testforcsdn]# tou CH Thrid
[root@localhost testforcsdn]# ls-l Total
-rw-r--r--1 root Oct 23:12 filelist-
R w-r--r--1 root   0 Oct 18:04-
-rw-r--r--1 root root   0 Oct 18:04 Second
-rw-r--r--1 ro OT root   0 Oct 18:34 thrid
[root@localhost testforcsdn]# touch-t 201410250935.40 thrid 
[root@localhost  testforcsdn]# ls-l Total
-rw-r--r--1 root Oct 23:12 filelist
-rw-r--r--1 root root   0 Oct 18:04-
-rw-r--r--1 root   0 Oct 18:04 Second
-rw-r--r--1 root root   0 Oct  2014 thrid

You can see that the time stamp was changed with-t

4 mkdir

Create a Directory

Common options

-m specify permissions at creation time

-p Specifies the path, if some directories on the path do not exist, it is created, that is, you can create a multi-tiered directory at once

-V Display Details

Example

[Root@localhost testforcsdn]# mkdir-m 777 Firstdir
[root@localhost
-testforcsdn]# ls-al Total Drwxr-xr-x  3 root root 4096 Oct 18:41.
Drwxr-x---root root 4096 Oct 17:56.
-rw-r--r--  1 root  Oct 23:12 filelist
-rw-r--r--  1 root    0 Oct 18:04
A-DRW XRWXRWX  2 root 4096 Oct 18:41 firstdir
-rw-r--r--  1 root root    0 Oct 18:04
second-rw-r --r--  1 root    0 Oct  2014 thrid
[root@localhost testforcsdn]# mkdir-p Thriddir
[root@localhost testforcsdn]# cd firstdir/seconddir/thriddir/
[root@localhost thridDir]# pwd
/root/testforcsdn/firstdir/seconddir/thriddir

As you can see, by-P creates a multi-tier directory once, and-M gives 777 of the permissions while creating the directory

5 CP

Copy

Common options

-B To delete the overwrite destination file before you back up

-I asks if you want to overwrite

-P retains the source file's or directory's properties: Owner, group, permission time

-R Copy Directory

Example

[root@localhost testforcsdn]# ls
filelist  firstdir  second  thrid
[root@localhost testforcsdn]# LS firstdir/
filelist  Second
[root@localhost testforcsdn]# cp thrid  firstdir/
[root@localhost testforcsdn]# cp-b filelist firstdir/
cp:overwrite ' firstdir/filelist ' y
[root@localhost testForCsdn]# ls firstdir/
filelist  filelist~  second  thrid
[root@localhost testforcsdn]# mkdir Seconddic
[root@localhost testforcsdn]# cp-r firstdir/seconddic/
[root@localhost testforcsdn]# ls seconddic/
firstdir

By the way, SCP: for instance,

SCP is a remote copy, if you want to remotely copy directory with-R

Scp-r root@192.168.0.12:~/testcsdn/localcsdn/

Copy the 192.168.0.12 ~/testcsdn to the localcsnd.

6, MV

Cut and rename

Example

[root@localhost testforcsdn]# ls
filelist  firstdir second seconddic thrid you
have new mail In/var/spool/mail/root
[root@localhost testforcsdn]# mkdir tempdic
[root@localhost testforcsdn]# ls
FileList  firstdir  second  seconddic  tempdic  thrid
[root@localhost testforcsdn]# MV FileList newName
[root@localhost testforcsdn]# mv NewName tempdic/
[root@localhost testforcsdn]# ls
Firstdir  Second  seconddic  tempdic  thrid
[root@localhost testforcsdn]# ls tempdic/
NewName

7 Cat More

are used to view the contents of a file

Cat is suitable for shorter files

More will Page view: Space page, enter the next line, Q exit

Cat filename

More filename

8 Head Tail

View the first few lines of a file, and the following lines

Tail-f can be used to dynamically view the following lines of a file

Example

9 Ln

Create soft and hard links

Soft Links: Shortcuts similar to Windows

Hard link: Two files synchronized update

Soft links can cross file systems, hard links cannot be

Example

Create a soft connection

[Root@localhost ~]# ln-s file.txt file.hardlink

Create a hard link

[root@localhost ~]# ln file.txt file.hardlink

As you can see, the number of hard links to file.txt becomes 2.

-rw-r--r--2 Root root   210 Oct 07:54 File.hardlink
lrwxrwxrwx 1 root root     8 Oct 19:14 File.softlink ; File.txt
-rw-r--r--2 root   210 Oct 07:54 file.txt

Then, modify the File.txt

Type TESTCSDN at file start

See Hard links again

[Root@localhost ~]# head-5 file.hardlink 
testforcsdn
backup
bin
boot
Dev

You can see that the contents are updated synchronously