Archive for the ‘Performance Tune’ Category


top command

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Show Processes Sorted by any Top Output Column – Press O and Press M

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Display Selected User in Top Output Using top -u

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Display Only Specific Process with Given PIDs Using top -p

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Display All CPUs / Cores in the Top Output – Press 1 (one)

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Refresh Unix Top Command Output On demand (or) Change Refresh Interval Press d

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 Highlight Running Processes in the Linux Top Command Output – Press z

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Split Top Output into Multiple Panels – Press A

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Sort by CPU Utilization Press shift + p

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Save Top Command Results press shift +w

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mpstat – Display basic info

 

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 mpstat – Display CPU statistics of individual CPU (or) Core

 

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mpstat – display statistics information of a particular CPU (or core)

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mpstat Version

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uptime command in Linux 

System Time:

This displays the time the system clock shows in 24 hour format:

System Uptime:

This shows you how long the system has been running for.  It will state “up” and then give a timeframe.  In this example picture the system has been running for 5 Hours 21 Minutes.  The time will keep track of hours and minutes.  Once a 24 hour period has past will then keep track of uptime by the number of days, hours and minutes.  Whenever a server is rebooted this timer is reset back to zero.

Number of Users Logged In:

This statistic shows you how many active users are logged into your system at a time.  Pending on the function of the system and if multiple people access it, it’s common to see more than just 1 user.

Load Average:

The load average is the actual usage being put on the server.  This number is signified anywhere from 0.0 up through whole numbers.  Each decimal point can be calculated to a percentage (ie. .01 equals 1% load average). The 3 numbers correspond with the load average for a given time frame during a 1 minute, 5 minute and 15 minute interval.  The lower the load average the better your system will perform.
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1.When i install my operating system 

 

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2.find Last reboot and date

 

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3. Logged information about Particular user

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4.find who are  all still logged in

 

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5.find who logged in particular terminal

 

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6. find out who was logged in bad attempts

 

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1. List all Open Files with lsof Command

 

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Sections and it’s values are self-explanatory. However, we’ll review FD & TYPE columns more precisely.

FD – stands for File descriptor and may seen some of the values as:

  1. cwd current working directory
  2. rtd root directory
  3. txt program text (code and data)
  4. mem memory-mapped file

Also in FD column numbers like 1u is actual file descriptor and followed by u,r,w of it’s mode as:

  1. r for read access.
  2. w for write access.
  3. u for read and write access.

TYPE – of files and it’s identification.

  1. DIR – Directory
  2. REG – Regular file
  3. CHR – Character special file.
  4. FIFO – First In First Out

2. List User Specific Opened Files

 

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3. Find Processes running on Specific Port

 

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4. List Only IPv4 & IPv6 Open Files

 

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5. List Open Files of TCP Port ranges 1-1024

 

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6. Exclude User with ‘^’ Character

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7. Find Out who’s Looking What Files and Commands?

 

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8. List all Network Connections

 

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9. Search by PID

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10. List all TCP or UDP connections

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6 Iostat Command Examples in Linux

 Display CPU and I/O statistics

 

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Shows only CPU Statistics

 

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Shows only Disks I/O Statistics

 

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Shows I/O statistics only of a single device.

 

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Display LVM Statistics

 

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iostat version.

 

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