/tmp as tmpfs

xworld · 2012-11-29 10:16:40

Hello Arch users, I had a question about mounting /tmp as tmpfs. I am worried it could somehow mess up the system. I read this:

Do not remove files from this directory unless you know exactly what you are doing! Many of these files are important for currently running programs and deleting them may result in a system crash.

In the wiki and I noticed there is a folder called: systemd-private-p9Qg9X in the /tmp folder. I am unable to delete it and I'm sure that is for the best. My question is this; Would mounting /tmp as tmpfs mess up my system since there is a folder in there that persists even after shutdown? It seems that it is supposed to stay there.

Thanks.

drenninghoff · 2012-11-29 10:30:55

No, /tmp will be regulary deleted even if you don't have it as tmpfs. The systemd-private folder is created by systemd on every boot.

So you can use /tmp as tmpfs without any problems. I would even suggest using it because new arch linux installations already have /tmp as tmpfs. Check out the default /etc/fstab file, it already contains a line for /tmp as tmpfs.

loafer · 2012-11-29 10:37:15

The default fstab no longer contains this at all. systemd takes care of it.

googol-1 · 2012-11-29 11:01:07

Most likely you are already using tmpfs

% grep /tmp /etc/mtab
tmpfs /tmp tmpfs rw 0 0

loafer · 2012-11-29 11:07:31

Unless you have changed it you will. It's the default for both systemd and initscripts. For example, look at /lib/systemd/system/tmp.mount.

[Unit]
Description=Temporary Directory
Documentation=man:hier(7)
DefaultDependencies=no
Conflicts=umount.target
Before=local-fs.target umount.target

[Mount]
What=tmpfs
Where=/tmp
Type=tmpfs
Options=mode=1777,strictatime

As such the entry is not required in /etc/fstab and has been removed.

Last edited by loafer (2012-11-29 11:07:47)

xworld · 2012-11-29 21:31:59

Ah I see, thanks for the replies everyone. I'm also curious about your opinions on encrypting the /tmp directory and how you think the best way to go about it is.

alphaniner · 2012-11-29 21:42:19

Depending on what you're doing, you might also consider using /dev/shm.

tomegun · 2012-11-29 22:08:43

xworld wrote:

Ah I see, thanks for the replies everyone. I'm also curious about your opinions on encrypting the /tmp directory and how you think the best way to go about it is.

If /tmp is on tmpfs (i.e., the default if you don't override it somehow), then encrypting it would not make any sense. However, as it will be (potentially) backed by swap, information written to /tmp might survive on your swap partition after a reboot. To avoid this you could encrypt your swap. I do this as follows:

/etc/fstab:
/dev/mapper/swap        swap            swap    nofail

/etc/crypttab:
swap    /dev/sda2       /dev/urandom    swap,nofail

The 'nofail' entries means that systm boot will not wait for the swap partition to be ready (as it might be a bit slow to set-up, and you probably don't need swap immediately at boot that makes sense in most cases).

xworld · 2012-11-29 23:11:47

Fortunately for me I never enabled the swap partition. I have plenty of RAM. I will look into using /dev/shm thanks alot for the info everyone.

Arch Linux

#1 2012-11-29 10:16:40

/tmp as tmpfs

#2 2012-11-29 10:30:55

Re: /tmp as tmpfs

#3 2012-11-29 10:37:15

Re: /tmp as tmpfs

#4 2012-11-29 11:01:07

Re: /tmp as tmpfs

#5 2012-11-29 11:07:31

Re: /tmp as tmpfs

#6 2012-11-29 21:31:59

Re: /tmp as tmpfs

#7 2012-11-29 21:42:19

Re: /tmp as tmpfs

#8 2012-11-29 22:08:43

Re: /tmp as tmpfs

#9 2012-11-29 23:11:47

Re: /tmp as tmpfs

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