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Manual page for fd(4)

fd - file descriptor files

DESCRIPTION

These files, conventionally called /dev/fd/0, /dev/fd/1, /dev/fd/2, and so on, refer to files accessible through file descriptors. If file descriptor n is open, these two system calls have the same effect: 





fd = open("/dev/fd/n",mode);


fd = dup(n);






On these files 
creat.2
is equivalent to
open,
and
mode
is ignored. 
As with 
dup,
subsequent reads or writes on 
fd
fail unless the original
file descriptor allows the operations. 


For convenience in referring to standard input,
standard output, and standard error, an additional
set of names is provided: 
/dev/stdin
is a synonym for 
/dev/fd/0,
/dev/stdout
for
/dev/fd/1,
and
/dev/stderr
for 
/dev/fd/2. 

SEE ALSO

creat.2
dup.2
open.2

DIAGNOSTICS



open.2
returns
-1
and 
EBADF
if the associated file descriptor is not open. 



	
	

	

	

	


	

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	Created by unroff & hp-tools.
	© by Hans-Peter Bischof.  All Rights Reserved (1997).
	

	Last modified 21/April/97