cliffhanger121599
asked on
shm filesystem
Can someone tell me what I need to do to mount the shm filesystem at start up? Certain programs require a shared memory segment at startup(so I'm told)and consequently won't run. From the startup log the shm filesystem isn't being mounted.
"shm filesystem"? I've never heard of such a beast. However the SysV IPC facility does provide for shared memory regions and the shm*() funtions that manipulate it. The functionality must be enabled in the kernel. I believe that it's typically enabled in distributed kernels, but if you've built a custom kernel you might have it disabled.
ASKER
Thanks. I have the sysv IPC facility enabled in the kernel and then I thought my problem lay here with this piece of text from the kernel doc.
Shared memory is now implemented using a new (minimal) virtual file
system, which you need to mount before programs can use shared memory.
To do this automatically at system startup just add the following line
to your /etc/fstab:
none /var/shm shm defaults 0 0
When I added this to fsab I got the message at startup that the file does not exist. Can you help me further? I do have a file called shm, but it contains nothing!
Shared memory is now implemented using a new (minimal) virtual file
system, which you need to mount before programs can use shared memory.
To do this automatically at system startup just add the following line
to your /etc/fstab:
none /var/shm shm defaults 0 0
When I added this to fsab I got the message at startup that the file does not exist. Can you help me further? I do have a file called shm, but it contains nothing!
Can you give me more of a reference as to where you found that? I've searched the 2.2.12 & 2.2.14 kernel documention and don't see anything like that. Also what program(s) are you trying to use that's complaining?
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ASKER
Thanks. Your right, I'm running 2.3.99 pre3(and trying to run Midi Player, Hdparm etc.) and apart from this problem it has been fine. When i read jyu 88's answer I thought , that's it - but now I find that the 'chmon' command is not recognised on my system. i.e. it doesn't exist. Where does this come from? Incidentally, I do have a shm file at /proc/sysvipc, is this relevent?
I think the command you want is chmod, not chmon, and it's found in /bin.
ASKER
Many thanks to jlevie for pointing out my error. Full marks to jyu 88 though for excellent answer. One last thing, what does the command 'chmod 755 /var/shm' do(I've just looked at the man file and it's as clear as mud!).