truncate.2 revision 1.12
$NetBSD: truncate.2,v 1.12 2000/06/17 19:33:34 hubertf Exp $
Copyright (c) 1983, 1991, 1993
The Regents of the University of California. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. All advertising materials mentioning features or use of this software
must display the following acknowledgement:
This product includes software developed by the University of
California, Berkeley and its contributors.
4. Neither the name of the University nor the names of its contributors
may be used to endorse or promote products derived from this software
without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.
@(#)truncate.2 8.1 (Berkeley) 6/4/93
.Dd June 4, 1993 .Dt TRUNCATE 2 .Os .Sh NAME .Nm truncate , .Nm ftruncate .Nd truncate a file to a specified length .Sh LIBRARY .Lb libc .Sh SYNOPSIS .Fd #include <unistd.h> .Ft int .Fn truncate "const char *path" "off_t length" .Ft int .Fn ftruncate "int fd" "off_t length" .Sh DESCRIPTION .Fn truncate causes the file named by .Fa path or referenced by .Fa fd to have a size of .Fa length bytes. If the file previously was larger than this size, the extra data is discarded. If it was previously shorter than .Fa length , its size is increased to the specified value and the extended area appears as if it were zero-filled. With .Fn ftruncate , the file must be open for writing; for .Fn truncate , the process must have write permissions for the file. .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 .Va errno specifies the error. .Sh ERRORS .Fn truncate succeeds unless: l -tag -width Er t Bq Er ENOTDIR A component of the path prefix is not a directory. t Bq Er ENAMETOOLONG A component of a pathname exceeded .Dv {NAME_MAX} characters, or an entire path name exceeded .Dv {PATH_MAX} characters. t Bq Er ENOENT The named file does not exist. t Bq Er EACCES Search permission is denied for a component of the path prefix, or the named file is not writable by the user. t Bq Er ELOOP Too many symbolic links were encountered in translating the pathname. t Bq Er EISDIR The named file is a directory. t Bq Er EROFS The named file resides on a read-only file system. t Bq Er ETXTBSY The file is a pure procedure (shared text) file that is being executed. t Bq Er EIO An I/O error occurred updating the inode. t Bq Er EFAULT .Fa path points outside the process's allocated address space. .El
Copyright (c) 1983, 1991, 1993
The Regents of the University of California. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. All advertising materials mentioning features or use of this software
must display the following acknowledgement:
This product includes software developed by the University of
California, Berkeley and its contributors.
4. Neither the name of the University nor the names of its contributors
may be used to endorse or promote products derived from this software
without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.
@(#)truncate.2 8.1 (Berkeley) 6/4/93
.Dd June 4, 1993 .Dt TRUNCATE 2 .Os .Sh NAME .Nm truncate , .Nm ftruncate .Nd truncate a file to a specified length .Sh LIBRARY .Lb libc .Sh SYNOPSIS .Fd #include <unistd.h> .Ft int .Fn truncate "const char *path" "off_t length" .Ft int .Fn ftruncate "int fd" "off_t length" .Sh DESCRIPTION .Fn truncate causes the file named by .Fa path or referenced by .Fa fd to have a size of .Fa length bytes. If the file previously was larger than this size, the extra data is discarded. If it was previously shorter than .Fa length , its size is increased to the specified value and the extended area appears as if it were zero-filled. With .Fn ftruncate , the file must be open for writing; for .Fn truncate , the process must have write permissions for the file. .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 .Va errno specifies the error. .Sh ERRORS .Fn truncate succeeds unless: l -tag -width Er t Bq Er ENOTDIR A component of the path prefix is not a directory. t Bq Er ENAMETOOLONG A component of a pathname exceeded .Dv {NAME_MAX} characters, or an entire path name exceeded .Dv {PATH_MAX} characters. t Bq Er ENOENT The named file does not exist. t Bq Er EACCES Search permission is denied for a component of the path prefix, or the named file is not writable by the user. t Bq Er ELOOP Too many symbolic links were encountered in translating the pathname. t Bq Er EISDIR The named file is a directory. t Bq Er EROFS The named file resides on a read-only file system. t Bq Er ETXTBSY The file is a pure procedure (shared text) file that is being executed. t Bq Er EIO An I/O error occurred updating the inode. t Bq Er EFAULT .Fa path points outside the process's allocated address space. .El
p .Fn ftruncate succeeds unless: l -tag -width Er t Bq Er EBADF The .Fa fd is not a valid descriptor. t Bq Er EINVAL The .Fa fd references a socket, not a file, or the .Fa fd is not open for writing. .El .Sh SEE ALSO .Xr open 2 .Sh BUGS These calls should be generalized to allow ranges of bytes in a file to be discarded. .Sh HISTORY The .Fn truncate and .Fn ftruncate function calls appeared in x 4.2 .