mknod
mknod creates special files — files that are not data but an interface to something else: a device, or a named pipe.
mknod [options] name type [major minor]
$ mknod /dev/mydisk b 8 0
$ mknod backlog p
The type argument #
The type says what kind of special file to create:
| Type | Creates |
|---|---|
b | A block device — a device addressed in fixed-size blocks, such as a disk. |
c or u | A character device — a device addressed as a stream of bytes, such as a terminal. |
p | A named pipe (FIFO). |
For a block or character device (b, c, u) you must also give a major and a minor number. The major number selects which driver handles the device; the minor number tells that driver which specific device is meant. For a pipe (p), the major and minor numbers are omitted — a pipe has no driver behind it.
A major or minor number is read as hexadecimal if it begins with 0x, as octal if it begins with 0, and as decimal otherwise.
mknod NAME p and mkfifo NAME do the same thing; mkfifo exists as the clearer way to ask for just a pipe.
Setting the new file's security #
A special file needs a security descriptor like any other file, and by default a new one inherits its descriptor from the directory it is created in.
mknod accepts the shared creation flags — --owner, --group, --label, --no-inherit, and --sddl — to set that descriptor explicitly. They behave exactly as they do for mkdir; the full reference is on the mkdir page.
Exit status #
| Code | Meaning |
|---|---|
0 | The special file was created. |
1 | It could not be created — a missing or invalid type, missing device numbers, or a name that already exists. |