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.\" Created   Wed Aug  9 1995     Thomas K. Dyas <tdyas@eden.rutgers.edu>
.\"
.TH SYSFS 2 2010-06-27 "Linux" "Linux Programmer's Manual"
.SH NAME
sysfs \- get file system type information
.SH SYNOPSIS
.BI "int sysfs(int " option ", const char *" fsname );

.BI "int sysfs(int " option ", unsigned int " fs_index ", char *" buf );

.BI "int sysfs(int " option );
.SH DESCRIPTION
.BR sysfs ()
returns information about the file system types currently present in
the kernel.
The specific form of the
.BR sysfs ()
call and the information returned depends on the
.I option
in effect:
.TP 3
.B 1
Translate the file-system identifier string
.I fsname
into a file-system type index.
.TP
.B 2
Translate the file-system type index
.I fs_index
into a null-terminated file-system identifier string.
This string will
be written to the buffer pointed to by
.IR buf .
Make sure that
.I buf
has enough space to accept the string.
.TP
.B 3
Return the total number of file system types currently present in the
kernel.
.PP
The numbering of the file-system type indexes begins with zero.
.SH RETURN VALUE
On success,
.BR sysfs ()
returns the file-system index for option
.BR 1 ,
zero for option
.BR 2 ,
and the number of currently configured file systems for option
.BR 3 .
On error, \-1 is returned, and
.I errno
is set appropriately.
.SH ERRORS
.TP
.B EFAULT
.RI "Either " fsname " or " buf
is outside your accessible address space.
.TP
.B EINVAL
.I fsname
is not a valid file-system type identifier;
.I fs_index
is out-of-bounds;
.I option
is invalid.
.SH CONFORMING TO
SVr4.
.SH NOTES
This System-V derived system call is obsolete; don't use it.
On systems with
.IR /proc ,
the same information can be obtained via
.IR /proc/filesystems ;
use that interface instead.
.SH BUGS
There is no libc or glibc support.
There is no way to guess how large \fIbuf\fP should be.