What is free?
5 free examples
Syntax and Options
Related Commands
What is free?
Free displays the total amount of used and free space of physical memory and swap memory in the system.
5 free Examples
1. Display the Current Usage Status of Memory
By default without any options, free command shows the used and free space of physical and swap memory in KB units as shown below,
$ free
total used free shared buffers cached
Mem: 509336 462216 47120 0 71408 215684
-/+ buffers/cache: 175124 334212
Swap: 915664 11928 903736
2. Switch the free Output in KB, or MB, or GB
Free allows you to display the size of memory space in bytes or KB or MB or GB as shown below,
$ free -b
total used free shared buffers cached
Mem: 521560064 474198016 47362048 0 73826304 220983296
-/+ buffers/cache: 179388416 342171648
Swap: 937639936 12210176 925429760
$ free -k
total used free shared buffers cached
Mem: 509336 463084 46252 0 72104 215804
-/+ buffers/cache: 175176 334160
Swap: 915664 11924 903740
$ free -m
total used free shared buffers cached
Mem: 497 452 45 0 70 210
-/+ buffers/cache: 171 326
Swap: 894 11 882
$ free -g
total used free shared buffers cached
Mem: 0 0 0 0 0 0
-/+ buffers/cache: 0 0
Swap: 0 0 0
3. Display the Totals Line
To display the totals line at the end, execute free command with -t option as shown below.
$ free -t
total used free shared buffers cached
Mem: 509336 463332 46004 0 72256 215804
-/+ buffers/cache: 175272 334064
Swap: 915664 11924 903740
Total: 1425000 475256 949744
4. Disable Buffer Adjusted Line Display
Free command displays the output with buffer line normally. You can disable that line in the display by using -o option as shown below
$ free -o
total used free shared buffers cached
Mem: 509336 463588 45748 0 72376 215856
Swap: 915664 11924 903740
5. Display the Usage Status Continuously for Regular Intervals
With -s optoin, you can activate the display of free to show it in every regular intervals as shown below.
$ free -s 3
total used free shared buffers cached
Mem: 509336 469604 39732 0 73260 216068
-/+ buffers/cache: 180276 329060
Swap: 915664 11924 903740
total used free shared buffers cached
Mem: 509336 468968 40368 0 73268 216060
-/+ buffers/cache: 179640 329696
Swap: 915664 11924 903740
total used free shared buffers cached
Mem: 509336 469092 40244 0 73272 216068
-/+ buffers/cache: 179752 329584
Swap: 915664 11924 903740
This will show it continously until you stop it.
Syntax and Options
free [-b | -k | -m | -g] [-o] [-s delay ] [-t] [-V]
| Short Option | Long Option | Option Description |
|---|---|---|
| -b | to show the amount of memory in bytes | |
| -k | to show the amount of memory in kilo bytes | |
| -m | to show the amount of memory in mega bytes | |
| -g | to show the amount of memory in giga bytes | |
| -t | to additionally display the line containing the totals | |
| -o | to disable the display of buffer adjusted line | |
| -s | to display free output in regular intervals.By default the given input intervals considered as seconds.You may also specify floating number for interval in microseconds | |
| -V | to display version information |
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