Updating mysql user password

root#mysql
mysql> use mysql;
mysql>

SET PASSWORD FOR 'user-name-here'@'hostname-name-here' = PASSWORD('new-password-here');  
or
UPDATE mysql.user SET Password=PASSWORD('new-password-here') WHERE User='user-name-here' AND Host='host-name-here';  

mysql>flush privileges
mysql>quit

Now restart mysqld

Find Command variants

1. Find Files Using Name in Current Directory

Find all the files whose name is server.txt in a current working directory.

# find . -name server.txt

./server.txt

2. Find Files Under Home Directory

Find all the files under /home directory with name server.txt.

# find /home -name server.txt

/home/server.txt

3. Find Files Using Name and Ignoring Case

Find all the files whose name is server.txt and contains both capital and small letters in /home directory.

# find /home -iname server.txt

./server.txt
./server.txt

4. Find Directories Using Name

Find all directories whose name is server in / directory.

# find / -type d -name server

/server

5. Find PHP Files Using Name

Find all php files whose name is server.php in a current working directory.

# find . -type f -name server.php

./server.php

6. Find all PHP Files in Directory

Find all php files in a directory.

# find . -type f -name "*.php"

./server.php
./login.php
./index.php

Part II – Find Files Based on their Permissions
7. Find Files With 777 Permissions

Find all the files whose permissions are 777.

# find . -type f -perm 0777 -print

8. Find Files Without 777 Permissions

Find all the files without permission 777.

# find / -type f ! -perm 777

9. Find SGID Files with 644 Permissions

Find all the SGID bit files whose permissions set to 644.

# find / -perm 2644

10. Find Sticky Bit Files with 551 Permissions

Find all the Sticky Bit set files whose permission are 551.

# find / -perm 1551

11. Find SUID Files

Find all SUID set files.

# find / -perm /u=s

12. Find SGID Files

Find all SGID set files.

# find / -perm /g+s

13. Find Read Only Files

Find all Read Only files.

# find / -perm /u=r

14. Find Executable Files

Find all Executable files.

# find / -perm /a=x

15. Find Files with 777 Permissions and Chmod to 644

Find all 777 permission files and use chmod command to set permissions to 644.

# find / -type f -perm 0777 -print -exec chmod 644 {} \;

16. Find Directories with 777 Permissions and Chmod to 755

Find all 777 permission directories and use chmod command to set permissions to 755.

# find / -type d -perm 777 -print -exec chmod 755 {} \;

17. Find and remove single File

To find a single file called server.txt and remove it.

# find . -type f -name "server.txt" -exec rm -f {} \;

18. Find and remove Multiple File

To find and remove multiple files such as .mp3 or .txt, then use.

# find . -type f -name "*.txt" -exec rm -f {} \;

OR

# find . -type f -name "*.mp3" -exec rm -f {} \;

19. Find all Empty Files

To file all empty files under certain path.

# find /tmp -type f -empty

20. Find all Empty Directories

To file all empty directories under certain path.

# find /tmp -type d -empty

21. File all Hidden Files

To find all hidden files, use below command.

# find /tmp -type f -name ".*"

Part III – Search Files Based On Owners and Groups
22. Find Single File Based on User

To find all or single file called server.txt under /root directory of owner root.

# find / -user root -name server.txt

23. Find all Files Based on User

To find all files that belongs to user server under /home directory.

# find /home -user server

24. Find all Files Based on Group

To find all files that belongs to group Developer under /home directory.

# find /home -group developer

25. Find Particular Files of User

To find all .txt files of user server under /home directory.

# find /home -user server -iname "*.txt"

Part IV – Find Files and Directories Based on Date and Time
26. Find Last 50 Days Modified Files

To find all the files which are modified 50 days back.

# find / -mtime 50

27. Find Last 50 Days Accessed Files

To find all the files which are accessed 50 days back.

# find / -atime 50

28. Find Last 50-100 Days Modified Files

To find all the files which are modified more than 50 days back and less than 100 days.

# find / -mtime +50 –mtime -100

29. Find Changed Files in Last 1 Hour

To find all the files which are changed in last 1 hour.

# find / -cmin -60

30. Find Modified Files in Last 1 Hour

To find all the files which are modified in last 1 hour.

# find / -mmin -60

31. Find Accessed Files in Last 1 Hour

To find all the files which are accessed in last 1 hour.

# find / -amin -60

Part V – Find Files and Directories Based on Size
32. Find 50MB Files

To find all 50MB files, use.

# find / -size 50M

33. Find Size between 50MB – 100MB

To find all the files which are greater than 50MB and less than 100MB.

# find / -size +50M -size -100M

34. Find and Delete 100MB Files

To find all 100MB files and delete them using one single command.

# find / -size +100M -exec rm -rf {} \;

35. Find Specific Files and Delete

Find all .mp3 files with more than 10MB and delete them using one single command.

# find / -type f -name *.mp3 -size +10M -exec ls -l {} \;

 

Find all empty files (zero byte file) in your home directory and its subdirectory

Most files of the following command output will be lock-files and place holders created by other applications.

# find ~ -empty

List all the empty files only in your home directory.

# find . -maxdepth 1 -empty

List only the non-hidden empty files only in the current directory.

# find . -maxdepth 1 -empty -not -name ".*"

Understanding VM Swap on Linux

VM swappiness is a setting in the Linux kernel that tells your system how aggressively it should use "swap space" compared to your computer's main memory (RAM). Think of swap space as a backup area on your hard drive that the system uses when RAM fills up.

• A high swappiness value means your system will try to move data from RAM to swap space more often.

• A low swappiness value means your system will try to keep data in RAM for longer, using swap space only when absolutely necessary.

In simple terms, the higher the swappiness value, the more your system will use the hard drive for memory overflow.

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DEFAULT SWAPPINESS VALUE

On many Linux distributions like RHEL and CentOS, the default swappiness value is often 60.

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HOW TO CHECK YOUR CURRENT SWAPPINESS

You can easily check the current swappiness value on your Linux system using one of these commands:

1. Using sysctl: sysctl vm.swappiness

   Example Output: vm.swappiness = 60

2. Reading the file directly: cat /proc/sys/vm/swappiness

   Example Output: 60

Both commands will show you the current swappiness setting.