. \"  Manual Seite fuer fdown
. \" @(#)fdown.3	1.1
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.TH FDOWN 3 "15. Juli 1988" "J\*org Schilling" "Schily\'s LIBRARY FUNCTIONS"
.SH NAME
fdown() \- returns a logical unit number
.SH SYNOPSIS
.nf
.B
int fdown(f)
.B	FILE *f;
.fi
.SH DESCRIPTION
fdown(), given a standard I/O FILE *f, returns the file
number. A file number is usually a small number like 2
which is not a unique number system-wide but is peculiar to the
specified process.
fdown() can be used to implement additional functions not
provided for in the standard I/O library. It verifies that the
file was opened via fileopen().
.SH RETURNS
Returns the actual system file number.
.SH NOTES
Since this call is system dependent, it should be used
carefully.