harvey/sys/man/4/ramfs

.TH RAMFS 4
.SH NAME
ramfs  \- memory file system
.SH SYNOPSIS
.B ramfs
[
.B -Dipsu
]
[
.B -m
.I mountpoint
]
[
.B -S
.I srvname
]
.SH DESCRIPTION
.I Ramfs
starts a process that mounts itself (see
.IR bind (2))
on
.I mountpoint
(default
.BR /tmp ).
The
.I ramfs
process implements a file tree rooted at
.IR dir ,
keeping all files in memory.
Initially the file tree is empty.
.PP
The
.B -D
option enables a trace of general debugging messages.
.PP
The
.B -i
flag tells
.I ramfs
to use file descriptors 0 and 1 for its communication channel
rather than create a pipe.
This makes it possible to use
.I ramfs
as a file server on a remote machine: the file descriptors 0
and 1 will be the network channel from
.I ramfs
to the client machine.
.PP
The
.B -p
flag causes
.I ramfs
to make its memory `private'
(see
.IR proc (3))
so that its files are not accessible through the debugging interface.
.PP
The
.B -s
.RB ( -S )
flag causes
.I ramfs
to post its channel on
.B /srv/ramfs
.RB ( /srv/ \fIsrvname\fR)
rather than mounting it on
.IR mountpoint ,
enabling multiple clients to access its files.
However, it does not authenticate its clients and its
implementation of groups is simplistic, so
it should not be used for precious data.
.PP
The
.B -u
option permits
.I ramfs
to consume as much memory as needed;
without it,
.I ramfs
will limit its consumption to some arbitrary amount,
currently 768MB (enough to hold a CD image).
.PP
This program is useful mainly as an example of how
to write a user-level file server.
It can also be used to provide high-performance temporary files.
.SH SOURCE
.B /sys/src/cmd/ramfs.c
.SH "SEE ALSO"
.IR bind (2)