[arch-general] tmpfs
Good day everyone, I want to delete the next two lines from my fstab: none /dev/pts devpts defaults 0 0 none /dev/shm tmpfs defaults 0 0 however I would like to know the secondary effects of doing such thing, all the information I could get on the internet is that shm is for POSIX shared memory support and that almost any program actually use it, for devpts I couldn't find much information about it. does anyone knows if it is safe to remove those lines from my fstab? thank you.
On Fri, 2010-03-26 at 00:53 +0900, Juan Diego wrote:
Good day everyone,
I want to delete the next two lines from my fstab:
none /dev/pts devpts defaults 0 0 none /dev/shm tmpfs defaults 0 0
however I would like to know the secondary effects of doing such thing, all the information I could get on the internet is that shm is for POSIX shared memory support and that almost any program actually use it, for devpts I couldn't find much information about it.
does anyone knows if it is safe to remove those lines from my fstab?
thank you.
/dev/pts is required for virtual terminals like xterm, gnome-terminal and others. Without that filesystem you can't start a virtual terminal. /dev/shm is used for shared memory, it's a requirement for NPTL semaphore functions. Now that /dev is also on tmpfs, I don't know if it's harmful to remove. The main requirement is that this folder has 1777 permissions.
Am 25.03.2010 16:53, schrieb Juan Diego:
Good day everyone,
I want to delete the next two lines from my fstab:
none /dev/pts devpts defaults 0 0 none /dev/shm tmpfs defaults 0 0
however I would like to know the secondary effects of doing such thing, all the information I could get on the internet is that shm is for POSIX shared memory support and that almost any program actually use it, for devpts I couldn't find much information about it.
does anyone knows if it is safe to remove those lines from my fstab?
This is definitely NOT SAFE! If you don't have /dev/shm, POSIX shared memory will use the same tmpfs filesystem as /dev, which is currently limited to 10MB - POSIX shared memory blocks might be much larger. As for removing /dev/pts, I was tempted to tell you to do it, as it's SO funny what happens: No pseudo TTYs are available anymore. This will effectively prevent ssh logins, screen, any X terminal and probably many more applications from allocating a TTY, so the only way to get a shell is to login via a real TTY (console). I am curious, why would you want to remove these? I am glad thouh that you asked BEFORE killing your system instead of after.
On Thu, Mar 25, 2010 at 5:07 PM, Thomas Bächler <thomas@archlinux.org> wrote:
This is definitely NOT SAFE!
If you don't have /dev/shm, POSIX shared memory will use the same tmpfs filesystem as /dev, which is currently limited to 10MB - POSIX shared memory blocks might be much larger.
As for removing /dev/pts, I was tempted to tell you to do it, as it's SO funny what happens: No pseudo TTYs are available anymore. This will effectively prevent ssh logins, screen, any X terminal and probably many more applications from allocating a TTY, so the only way to get a shell is to login via a real TTY (console).
I am curious, why would you want to remove these? I am glad thouh that you asked BEFORE killing your system instead of after.
Random suggestion : adding a one-line comment before these two entries describing what they are for (i.e. sumup of the above) :)
Am 25.03.2010 17:12, schrieb Xavier Chantry:
On Thu, Mar 25, 2010 at 5:07 PM, Thomas Bächler <thomas@archlinux.org> wrote:
This is definitely NOT SAFE!
If you don't have /dev/shm, POSIX shared memory will use the same tmpfs filesystem as /dev, which is currently limited to 10MB - POSIX shared memory blocks might be much larger.
As for removing /dev/pts, I was tempted to tell you to do it, as it's SO funny what happens: No pseudo TTYs are available anymore. This will effectively prevent ssh logins, screen, any X terminal and probably many more applications from allocating a TTY, so the only way to get a shell is to login via a real TTY (console).
I am curious, why would you want to remove these? I am glad thouh that you asked BEFORE killing your system instead of after.
Random suggestion : adding a one-line comment before these two entries describing what they are for (i.e. sumup of the above) :)
Patches welcome. Personally, I don't think it's worth the time - anyone who is going to mess with these entries is either expected to know what they are for or fail miserably. However, as someone who has been messing with this stuff for 10 years, I am probably not the right person to ask.
I wanted to remove them because I was cleaning my fstab of old entries that I dont use anymore, so I found those two in the middle of the way, I guess they will have to stay there On Fri, Mar 26, 2010 at 1:22 AM, Thomas Bächler <thomas@archlinux.org> wrote:
Am 25.03.2010 17:12, schrieb Xavier Chantry:
On Thu, Mar 25, 2010 at 5:07 PM, Thomas Bächler <thomas@archlinux.org> wrote:
This is definitely NOT SAFE!
If you don't have /dev/shm, POSIX shared memory will use the same tmpfs filesystem as /dev, which is currently limited to 10MB - POSIX shared memory blocks might be much larger.
As for removing /dev/pts, I was tempted to tell you to do it, as it's SO funny what happens: No pseudo TTYs are available anymore. This will effectively prevent ssh logins, screen, any X terminal and probably many more applications from allocating a TTY, so the only way to get a shell is to login via a real TTY (console).
I am curious, why would you want to remove these? I am glad thouh that you asked BEFORE killing your system instead of after.
Random suggestion : adding a one-line comment before these two entries describing what they are for (i.e. sumup of the above) :)
Patches welcome.
Personally, I don't think it's worth the time - anyone who is going to mess with these entries is either expected to know what they are for or fail miserably. However, as someone who has been messing with this stuff for 10 years, I am probably not the right person to ask.
On Fri, 2010-03-26 at 01:47 +0900, Juan Diego wrote:
I wanted to remove them because I was cleaning my fstab of old entries that I dont use anymore, so I found those two in the middle of the way, I guess they will have to stay there
Bottom-posting, please... And yes, I've wanted to remove them before. Thankfully google set me right on that one.
participants (5)
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Jan de Groot
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Juan Diego
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Ng Oon-Ee
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Thomas Bächler
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Xavier Chantry