.\" Copyright (c) 1983, 1991 The Regents of the University of California.
.\" All rights reserved.
.\"
+.\" %%%LICENSE_START(BSD_4_CLAUSE_UCB)
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
+.\" %%%LICENSE_END
.\"
.\" @(#)truncate.2 6.9 (Berkeley) 3/10/91
.\"
.\" Modified 2002-04-06 by Andries Brouwer <aeb@cwi.nl>
.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
.\"
-.TH TRUNCATE 2 2009-02-28 "Linux" "Linux Programmer's Manual"
+.TH TRUNCATE 2 2013-04-01 "Linux" "Linux Programmer's Manual"
.SH NAME
truncate, ftruncate \- truncate a file to a specified length
.SH SYNOPSIS
.BR feature_test_macros (7)):
.in
.ad l
+.PD 0
.sp
.BR truncate ():
-_BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500
+.RS 4
+_BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
+_XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
.br
+|| /* Since glibc 2.12: */ _POSIX_C_SOURCE\ >=\ 200809L
+.RE
+.sp
.BR ftruncate ():
-_BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500 || _POSIX_C_SOURCE\ >=\ 200112L
+.RS 4
+_BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
+_XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
+.br
+|| /* Since glibc 2.3.5: */ _POSIX_C_SOURCE\ >=\ 200112L
+.RE
+.PD
.ad b
.SH DESCRIPTION
The
the file must be open for writing; with
.BR truncate (),
the file must be writable.
-.SH "RETURN VALUE"
+.SH RETURN VALUE
On success, zero is returned.
On error, \-1 is returned, and
.I errno
is larger than the maximum file size. (XSI)
.TP
.B EINTR
-A signal was caught during execution.
+While blocked waiting to complete,
+the call was interrupted by a signal handler; see
+.BR fcntl (2)
+and
+.BR signal (7).
.TP
.B EINVAL
The argument
.B EIO
An I/O error occurred updating the inode.
.TP
-.B EINTR
-While blocked waiting to complete,
-the call was interrupted by a signal handler; see
-.BR fcntl (2)
-and
-.BR signal (7).
-.TP
.B EISDIR
The named file is a directory.
.TP
.B EINVAL
.I fd
does not reference a regular file.
-.SH "CONFORMING TO"
+.SH CONFORMING TO
4.4BSD, SVr4, POSIX.1-2001 (these calls first appeared in 4.2BSD).
.\" POSIX.1-1996 has
.\" .BR ftruncate ().
.\" .BR ftruncate ()
.\" an additional EAGAIN error condition.
.SH NOTES
-The above description is for XSI-compliant systems.
+The details in DESCRIPTION are for XSI-compliant systems.
For non-XSI-compliant systems, the POSIX standard allows
two behaviors for
.BR ftruncate ()
.BR truncate ()
is not specified at all in such an environment):
either returning an error, or extending the file.
-Like most Unix implementations, Linux follows the XSI requirement
+Like most UNIX implementations, Linux follows the XSI requirement
when dealing with native file systems.
However, some nonnative file systems do not permit
.BR truncate ()
to be used to extend a file beyond its current length:
a notable example on Linux is VFAT.
.\" At the very least: OSF/1, Solaris 7, and FreeBSD conform, mtk, Jan 2002
-.SH "SEE ALSO"
+
+The original Linux
+.BR truncate ()
+and
+.BR ftruncate ()
+system calls were not designed to handle large file offsets.
+Consequently, Linux 2.4 added
+.BR truncate64 ()
+and
+.BR ftruncate64 ()
+system calls that handle large files.
+However, these details can be ignored by applications using glibc, whose
+wrapper functions transparently employ the more recent system calls
+where they are available.
+
+On some 32-bit architectures,
+the calling signature for these system calls differ,
+for the reasons described in
+.BR syscall (2).
+.SH BUGS
+A header file bug in glibc 2.12 meant that the minimum value of
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=12037
+.BR _POSIX_C_SOURCE
+required to expose the declaration of
+.BR ftruncate ()
+was 200809L instead of 200112L.
+This has been fixed in later glibc versions.
+.SH SEE ALSO
.BR open (2),
.BR stat (2),
.BR path_resolution (7)
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