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Rhcsa Road

2022-07-01 16:34:00 【Omniscient magical conch】

The fourth day

File search 4 Ways of planting

whereis The query scope searches for files through the path of system environment variables $PATH, All documents

[[email protected] ~]# whereis ls 
ls: /usr/bin/ls /usr/share/man/man1/ls.1.gz /usr/share/man/man1p/ls.1p.gz 
[[email protected] ~]# whereis pwd 
pwd: /usr/bin/pwd /usr/share/man/man1/pwd.1.gz /usr/share/man/man1p/pwd.1p.gz

which The query scope searches for files through the path of system environment variables $PATH, Looking for executable （ Find command file ）

[[email protected] ~]# which locate 
/usr/bin/locate 
[[email protected] ~]# which whereis 
/usr/bin/whereis

locate Global search , But you need to import the system files into the database before searching updatedb; Fast search speed

[[email protected] ~]# locate whereis 
/usr/bin/whereis 
/usr/share/bash-completion/completions/whereis 
/usr/share/man/man1/whereis.1.gz

*find Global search for files .

Parameters	effect
-name	Match name
-perm 644	Match permissions （mode For a perfect match ,-mode Just for inclusion ）
-user	Match users
-group	Match all groups
-mtime -n +n	Match when the content was modified （-4 Means less than or equal to 4 File name within days ;+4, Greater than or equal to 5 Documents before name ;4 Forefinger 4~5 The documents of that day ）
-atime -n +n	Match access time to file
-ctime -n +n	Match when the file permission was modified
-nouser	Match files without owner
-nogroup	Match files without all groups
-newer f1 !f2	Matching ratio file f1 New than f2 Old documents
-type b/d/c/p/l/f	Match file type （ The following alphanumeric parameters in turn represent block devices 、 Catalog 、 Character device 、 The Conduit 、 link file 、 text file ）
-size	Match file size （+50KB To find more than 50KB The file of , and -50KB To find less than 50KB The file of ）
prune	Ignore a directory
-exec …… {}\;	This can be followed by commands for further processing of search results

matters needing attention ：

find Find the directory of the file -path Directory to exclude -prune -o -name What to query

1）-prune It has to be with -path,-o Use it together

2）-prune -o The order is not Can exchange

3）-name Etc. must be placed in -prune -o You can use it later

eg: find . -path ./tmp -prune -o -name "*.txt"

1. Search by filename

[[email protected] ~]# find  Search path  [ Options ]  Search content  
 Options ：
-name：  Search by filename  
-iname：  Search by filename , Case insensitive file names  
-inum：  according to  inode  Search on

2. Search by file size

[[email protected] ~]# find  Search path  [ Options ]  Search content  
 Options ：
-size [+|-] size ：  Search for files of the specified size   there “+” Search for files larger than the specified size , “-” Search for a text smaller than the specified size   Pieces of

3. Search for

[[email protected] ~]# find  Search path  [ Options ]  Search content  
 Options ：
-atime [+|-] Time ：  Search by file access time  
-mtime [+|-] Time ：  Search by file data modification time  
-ctime [+|-] Time ：  Search according to file status modification time

Time lookup parameters ：

-atime -n : take n*24 List the files fetched in hours of memory

-ctime -n : take n*24 Change in hours 、 List the new files or directories

-mtime -n : take n*24 List the files or directories modified within hours

-newer fifile ： Compare fifile And list new documents

4. Search by permissions

Command format .

[[email protected] ~]# find Search path [ Options ] Search content

Options ：

-perm Access mode ： Find file permissions exactly equal to “ Access mode ” The file of

-perm - Access mode ： Find file permissions include “ Access mode ” The file of

-perm + Access mode ： Find file permissions include “ Access mode ” Any one of the permissions of the file

5. Search by owner and group

[[email protected] ~]# find Search path [ Options ] Search content

Options ：

-uid user ID： According to the user ID Finding the owner is specifying ID The file of

-gid Group ID： By user group ID To find the group you belong to is to specify ID The file of

-user user name ： Find the file whose owner is the specified user by user name

-group Group name ： Find the file whose group is the specified user group according to the group name

-nouser： Find files that have no owner

6. Search by file type

[[email protected] ~]# find Search path [ Options ] Search content

Options ：

-type d： Look up the directory

-type f： Search for common files

-type l： Find the soft link file

7. Logical operators

[[email protected] ~]# find Search path [ Options ] Search content

Options ：

-a： and Logic and 1

-o： or Logic or

-not： not Logic is not

-exec and xargs The difference between

-exec

1. Parameters are passed one by one , Pass a parameter to execute once rm

2. File names with special characters such as spaces can also be processed

xargs

1. Pass parameters to the command at one time , have access to -n Number of control parameters

2. Handling special file names requires the following methods ：

fifind . -name "*.txt" print0 |xargs -0 rm {}

-xargs Use ：

xargs It's a strong order , It can capture the output of a command , And then pass it on to another command .

Why can I use this command , The point is that many commands don't support | Pipes to pass parameters , And it's necessary in daily work ,

So there it is xargs command , for example ：

find /sbin -perm +700 |ls -l # This command is wrong

find /sbin -perm +700 |xargs ls -l # That's the right thing to do

xargs Generally used with pipes .

Command format ：

somecommand |xargs -item command

Parameters ：

-a file Read from the file as stdin

-e flag , Note that sometimes it may be -E,flag Must be a space separated flag , When xargs Analyze to contain

flag Stop at this sign .

-p When one at a time argument Ask the user .

-n num Number of times after , Indicates that the command is used once during execution argument The number of , The default is to use all .

-t Print command first , And then execute .

-i Or is it -I, It depends on linux Support , take xargs The name of each item of , It's usually assigned line by line to {}, It can be used {}

Instead of .

-r no-run-if-empty When xargs When the input of is empty, it will stop xargs, There's no need to execute .

-s num The maximum number of characters on the command line , refer to xargs The maximum number of command line characters for the next command .

-L num Read once from standard input num Give it to command command .

-l Same as -L.

-d delim Separator , default xargs The separator is carriage return ,argument The separator for is a space , What's changed here is xargs Of

Separator .

-x exit It means , The main thing is to cooperate with -s Use ..

-P Modify the maximum number of processes , The default is 1, by 0 The time is as many as it can

File compression and decompression

tar Filing order

Format ：tar [ Options ] Package file name List of packaged source files or directories

tar [ Options ] Package file name [-C Destination folder ]

Options	function
c	establish .tar In the form of Bao Wenjian
x	Release .tar In the form of Bao Wenjian
t	View the list of files in the package
v	Indicates that detailed prompt information is displayed when the command is executed
f Baowen Piece name	Used to specify the package file name . When and -c When used with options , Created tar The package file uses the file name specified by this option ; When and -x When used with options , Release the... Specified by this option tar Package file
p	Preserve the permissions of files and directories when packaging
z	call gzip Program , With gzip Compress or decompress the file in the format .
j	call bzip2 Program , With bzip2 Compress or decompress the file in the format .
J	Use xz Compress （.tar.xz）.xz The compression ratio is usually higher than bzip2 Higher .
C Catalog route name	When releasing a package, specify the location of the target to be released .

1. establish ( Uncompressed ) Package file

command ：tar cvf Package file name List of directories or file names to package

function ： Backup one or more specified files or directories into a specified package file .

2. Create a package file with compression

To save storage space , You usually need to generate a compressed format tar Package file ,tar The command supports three different compression methods ：

command ：tar c[z j|J] f Zip package filename Directory or file name to back up

example 3： Look at the contents of the compressed file

[[email protected] test]# xzcat test1.txt.xz

test1

example 4： decompression （xz -d Equivalent to unxz）

[[email protected] test]# unxz test1.txt.xz

example 5： Extract directory dir1 The file

[[email protected] test]# xz -d dir1/*

[[email protected] test]# ls dir1

fstab test3.txt test4.txt test5.txt

Show the contents of the compressed file ：zcat、zless、bzcat、bzless

Do not decompress , Show the contents of the compressed file ：zcat、zless、bzcat、bzless.

1．zcat、zless**

[[email protected] test]# zcat test2.txt.gz

test2

2．bzcat、bzless**

for example ：

# bzcat man.config.bz2 // Show... On the screen man.config.bz2 Decompressed content

3. List the files in the package file

command ：tar t[v]f Package file name

4. Extract the package file to the specified directory

Format ：tar x [z j|J] [v]f Package file name [ -C Target location ]

tar Exclude when packing ：

--exclude=PATTERN To exclude with PATTERN Specified file

-X, --exclude-from=FILE exclude FILE The pattern strings listed in

SFTP

1、sftp Is an interactive file transfer program

It is similar to ftp Transfer protocol , Belong to ssh, But it's encrypted transmission , relative FTP It has higher security .

sftp usage

If the port of a server is not the default 22, Please be there. sftp Back plus -P Port number that will do .

# sftp [email protected]

The authenticity of host ‘223.6.6.6 (223.6.6.6)’ can’t be established.

ECDSA key fingerprint is SHA256:Hl/dKTFzL4lOlF8DIG5itaV4OAsZunC2AWlFGLjLfsg.

Are you sure you want to continue connecting (yes/no)? yes【 Input yes enter 】

Warning: Permanently added ‘223.6.6.6’ (ECDSA) to the list of known hosts.

[email protected]’s password:【 Input 223.6.6.6 Of root Password and enter 】

Connected to 223.6.6.6.

sftp>

take 223.6.6.6 Download the server file to 223.5.5.5 Of home Catalog ;

sftp> get /var/www/renwole.txt /home/

take 223.5.5.5 Upload server files to 223.6.6.6 Server's mnt Catalog ;

sftp> put /home/renwole.txt /mnt/

If you don't know what the remote host's directory looks like , ls command Can be listed 223.6.6.6 The current directory list of the server . for example ：

sftp> ls // Just like viewing local operation commands

sftp> pwd // Inquire about 223.6.6.6 Current working directory for

Changing the path can be done with cd , Changing the local path can use cd.. for example ;

sftp> cd

If you want to quit , for example ：

# exit // Exit the machine , Return to your original machine interface .

2、scp With and ssh The same validation mechanism , So that 2 Secure remote copy of files from one machine

scp Can be summed up as ：scp -P port File path user name @ The host address : Remote directory -r

If you want to copy local files to another computer ssh terminal , You can use the following command

# scp /renwole/mariadb.tar.gz [email protected]:/renwole123/

[email protected]’s password:【 Enter the password and press enter 】

mariadb.tar.gz 8% 37MB 1.3MB/s 05:29 ETA

# scp test.tar.bz2 [email protected]:/ Send a file

# scp [email protected]:/134 . Receive the file

If you operate in reverse , Copy the files of the remote host to the current system , The operation commands are as follows

# scp [email protected]:/renwole123/mariadb.tar.gz /renwole

If you want to copy the folder and all the files in it , Just add parameters -r If your port number is not 22, So you need to scp Add one later -P ( Case sensitive ) Port number . Suggestion plus -C Options , Because it enables SSH The compression function of ; Faster transmission , for example

# scp -P 6632 -C /renwole/mariadb [email protected]:/renwole123/

alias Define command aliases

alias Alias =’ The original order - Options / Parameters ’

View the alias set ：alias

To delete an alias ：unalias Alias

[[email protected] ~]#

[[email protected] ~]# alias net="cat /etc/sysconfig/network-scripts/ifcfg-ens160"

[[email protected] ~]# unalias net

Alias permanent （ Strongly recommend ）：

alias The function of is only in the operation of this login , That is, enter once alias after , This modification is only available in the current Shell take effect . If you reopen

One Shell, Or log back in , Then these alias Will not be available . Fortunately linux Provided in the alias Permanent method ：

<1>. To take effect automatically every time you log in , Add alias to ~/.bashrc Back most

<2>. To make every user effective, alias , Add alias to /etc/bashrc Back most , then # source /etc/bashrc

Permanent cancellation , Delete /etc/bashrc Alias added later , Entry into force requires the adoption of bash perhaps

exit

Command cache

1. Build command cache

Execute the command to automatically create in the cache

hash -p /usr/bin/touch touch

hash -p /usr/bin/touch chuangjian

2. Delete cache

hash -d chuangjian

hash -r Empty all caches

exit terminal

Caching features ： Command cache ---alias-- Name order document

[[email protected] ~]# hash
hits   command
   3   /usr/bin/vim
   1   /usr/bin/cat
   1   /usr/sbin/pidof
   2   /usr/bin/su
[[email protected] ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin
[[email protected] ~]# which touch
/usr/bin/touch
[[email protected] ~]# touch a
[[email protected] ~]# hash
hits   command
   3   /usr/bin/vim
   1   /usr/bin/cat
   1   /usr/bin/touch
   1   /usr/sbin/pidof
   2   /usr/bin/su
[[email protected] ~]# touch /usr/bin/touch     ---= Priority through cache matching
[[email protected] ~]# hash
hits   command
   3   /usr/bin/vim
   1   /usr/bin/cat
   2   /usr/bin/touch
   1   /usr/sbin/pidof
   2   /usr/bin/su

[[email protected] ~]# mv /usr/bin/touch /usr/local/bin
[[email protected] ~]# touch b
bash: /usr/bin/touch: No such file or directory
[[email protected] ~]# hash -d touch
[[email protected] ~]# hash
hits   command
   3   /usr/bin/vim
   1   /usr/bin/cat
   1   /usr/sbin/pidof
   3   /usr/bin/mv
   2   /usr/bin/su
[[email protected] ~]# touch b     ---- There is no cache and the command file under the alias execution environment variable path
[[email protected] ~]# hash -p /usr/bin/tac chakan    -- Alias