LinuxQuestions.org - [SOLVED] swap file and partition reboot issue with free cmd

- Linux - Newbie (https://www.linuxquestions.org/questions/linux-newbie-8/)

- - swap file and partition reboot issue with free cmd (https://www.linuxquestions.org/questions/linux-newbie-8/swap-file-and-partition-reboot-issue-with-free-cmd-4175574590/)

swap file and partition reboot issue with free cmd

I had a standard CentOS 7 partition layout with /boot, /, /var, and swap (2G) partitions carved out.
So the free cmd showed me that I had 2G total.

As a test, I added roughly 500MB more swap through a swap file:

Code:

# free

# dd if=/dev/zero of=/extra-swap bs=1M count=500

# mkswap /extra-swap

# swapon -a

# free

At this point, the free command returned same amount, roughly 2G. So I added the swap file to my fstab to make it persistent then rebooted:

Code:

# vim /etc/fstab

...

/extra-swap          swap        swap      defaults 0 0 

...

# reboot

Upon reboot, the free cmd now showed 2.5G

My question is, why did free not show the swap until reboot?

Ideas and / or better ways to do this?

SK

Code:

swapon /extra-swap

# swapon -s

to list active swaps. Free lists if you have some, but not much else about it. And as above use swapon to add the file/partition in the absence of having it auto-magically happen because of fstab.

swap file and partition reboot issue with free cmd

swapon -a scans the fstab file for entries. It will not scan your partition layout.