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iostat

The iostat command is for getting the CPU and input-output devices' statistics for Linux and Unix systems. For example, $ iostat Linux 3.0.0-14-generic (hostname) Wednesday 06 June 2012 _i686_ (2 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 17.38 0.13 3.13 1.63 0.00 77.74 Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn sda 11.78 111.65 69.79 11663838 …

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vmstat

The vmstat command prints the system virtual memory statistics for Linux and Unix systems. vmstat prints information about system processes, memory, swap, I/O blocks, interrupts and context switches and the CPU activity. The most common command format is, vmstat [delay [count]] The optional delay parameter tells the time interval between periodic vmstat outputs. If the …

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uptime and w commands in Linux

The uptime and w commands in Linux and Unix systems give pointed information about the system uptime, load average and about logged in users. uptime The uptime command is given as, uptime And the output is like, 07:47:08 up 25 days, 17:54, 1 user, load average: 0.03, 0.09, 0.08 In the above output, 07:47:08 is …

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Finding the free and used memory with the free command

Using the free command, the free and used memory in a Linux or Unix system can be found. The free command can be given from the command line as, free And the system responds with an output like, total used free shared buffers cached Mem: 960268 873136 87132 0 14652 168884 -/+ buffers/cache: 689600 270668 …

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Load Average

Linux commands like top, uptime and w report the system load average. For instance, the first line of top command output is something like, top – 04:56:31 up 60 days, 23:18, 1 user, load average: 0.02, 0.06, 0.05 The last three numbers give the load average for the last one minute, five minutes and fifteen …

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top Command in Linux

The Unix top command is useful for monitoring systems continuously for processes that take more system resources like the CPU time and the memory. top periodically updates the display showing the high resource consuming processes at the top. top is an excellent aid in checking a system. If your Linux or Unix system is giving …

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ps command usage with examples in Linux

The ps command gives information about processes on a Linux or Unix system. Our programs run as processes in the system. Also, for each installed package, there might be one or more processes. So, to know what is happening in the system, the first instinctive action is to find out about processes running in the …

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cron

cron is a daemon that executes programs for users periodically at predefined times. The cron daemon or service is started by the init process during system initialization. cron comes from chronos, the Greek word for time. cron was authored by Brian Kernighan in Version 7 Unix. The 4th BSD edition cron, written by Paul Vixie …

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