---
name: "sysfs"
section: "2"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/sysfs"
---

# sysfs(2)

get filesystem type information

## NAME

sysfs - get filesystem type information

## SYNOPSIS

```
[[deprecated]] int sysfs(int option, const char *fsname);
[[deprecated]] int sysfs(int option, unsigned int fs_index, char *buf);
[[deprecated]] int sysfs(int option);
```

## DESCRIPTION

**Note**: if you are looking for information about the **sysfs** filesystem that is normally mounted at */sys*, see [**sysfs**(5)](/sysfs/5.md).

The (obsolete) **sysfs**() system call returns information about the filesystem types currently present in the kernel. The specific form of the **sysfs**() call and the information returned depends on the *option* in effect:

- **1**

  Translate the filesystem identifier string *fsname* into a filesystem type index.

- **2**

  Translate the filesystem type index *fs\_index* into a null-terminated filesystem identifier string. This string will be written to the buffer pointed to by *buf*. Make sure that *buf* has enough space to accept the string.

- **3**

  Return the total number of filesystem types currently present in the kernel.

The numbering of the filesystem type indexes begins with zero.

## RETURN VALUE

On success, **sysfs**() returns the filesystem index for option **1**, zero for option **2**, and the number of currently configured filesystems for option **3**. On error, -1 is returned, and *errno* is set to indicate the error.

## ERRORS

- **EFAULT**

  Either *fsname* or *buf* is outside your accessible address space.

- **EINVAL**

  *fsname* is not a valid filesystem type identifier; *fs\_index* is out-of-bounds; *option* is invalid.

## STANDARDS

None.

## HISTORY

SVr4.

This System-V derived system call is obsolete; don't use it. On systems with */proc*, the same information can be obtained via */proc*; use that interface instead.

## BUGS

There is no libc or glibc support. There is no way to guess how large *buf* should be.

## SEE ALSO

[**proc**(5)](/proc/5.md), [**sysfs**(5)](/sysfs/5.md)