gno/usr.man/man2/truncate.2

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1997-02-27 07:32:31 +00:00
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.\" @(#)truncate.2 8.1 (Berkeley) 6/4/93
.\"
.TH TRUNCATE 2 "24 January 1997" GNO "System Calls"
.SH NAME
.BR truncate ,
.BR ftruncate
\- truncate a file to a specified length
.SH SYNOPSIS
#include <unistd.h>
.sp 1
int
\fBtruncate\fR (const char *\fIpath\fR, off_t \fIlength\fR);
.br
int
\fBftruncate\fR (int \fIfd\fR, off_t \fIlength\fR);
.SH DESCRIPTION
.BR truncate
causes the file named by
.I path
or referenced by
.I fd
to be truncated to at most
.I length
bytes in size. If the file previously
was larger than this size, the extra data
is lost.
With
.BR ftruncate ,
the file must be open for writing.
.SH RETURN VALUES
A value of 0 is returned if the call succeeds. If the call
fails a -1 is returned, and the global variable
.IR errno
specifies the error.
.SH SEE ALSO
.BR open (2)
.SH BUGS
The GNO implementation of
.BR truncate
requires that the file must be able to be opened for writing. If
this is not possible,
.BR truncate
returns -1 and sets
.IR errno .
.LP
These calls should be generalized to allow ranges
of bytes in a file to be discarded.
.SH HISTORY
The
.BR ftruncate
function call appeared in 4.2BSD.