Unix::Mknod - Perl extension for mknod, major, minor, and makedev

 use Unix::Mknod qw(:all);
 use File::stat;
 use Fcntl qw(:mode);

 $st=stat('/dev/null');
 $major=major($st->rdev);
 $minor=minor($st->rdev);

 mknod('/tmp/special', S_IFCHR|0600, makedev($major,$minor+1));

This module allows access to the device routines major()/minor()/makedev() that may or may not be macros in .h files.

It also allows access to the mknod(2) system call.

mknod($filename, $mode, $rdev)

Creates a block or character device special file named $filename. Must be run as a privileged user, usually root. Returns 0 on success and -1 on failure, like POSIX::mkfifo does.

$major = major($rdev)

Returns the major number for the device special file as defined by the st_rdev field from the stat(3) call.

$minor = minor($rdev)

Returns the minor number for the device special file as defined by the st_rdev field from the stat(3) call.

$rdev = makedev($major, $minor)

Returns the st_rdev number for the device special file from the $major and $minor numbers.

There are 2 other perl modules that implement the mknod(2) system call, but they have problems working on some platforms. Sys::Mknod does not work on AIX because it uses the syscall(2) generic system call which AIX does not have. Mknod implements S_IFIFO, which on most platforms is not implemented in mknod(1), but rather mkfifo(1) (which is implemented in POSIX perl module).

The perl module File::Stat::Bits also implements major() and minor() (and a version of makedev() called dev_join). They are done as a program to get the bit masks at compile time, but if major() and minor() are implemented as sub routines, the arugment could be something as simple as an index to a lookup table (and thereby having no decernable relation to its result).

Running make test as non root will not truly test the functions, as in most UNIX like OSes, mknod(2) needs to be invoked by a privelaged user, usually root.

$ERRNO or $! for the specific error message.

File::Stat::Bits, Mknod, POSIX, Sys::Mknod

major(9), minor(9), mkfifo(1), mknod(8)

ftp://ftp-dev.cites.uiuc.edu/pub/Unix-Mknod

Jim Pirzyk, <pirzyk@uiuc.edu>

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