truncate.2 (2010 09)

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truncate(2) truncate(2)

NAME

ftruncate, truncate - truncate a ﬁle to a speciﬁed length

SYNOPSIS

#include <unistd.h>

int ftruncate(int fildes, off_t length);

int truncate(const char *path, off_t length);

DESCRIPTION

The ftruncate() function causes the regular ﬁle referenced by ﬁldes to have a size of length bytes.

The

truncate() function causes the regular ﬁle named by path to have a size of length bytes.

The effect of

ftruncate() and truncate()

on other types of ﬁles is unspeciﬁed. If the ﬁle previously

was larger than length, the extra data is lost. If it was previously shorter than length , bytes between the

old and new lengths are read as zeroes. With

ftruncate(), the ﬁle must be open for writing; for trun-

cate(), the process must have write permission for the ﬁle.

If the request would cause the ﬁle size to exceed the soft ﬁle size limit for the process, the request will fail

and the implementation will generate the

SIGXFSZ signal for the process.

These functions do not modify the ﬁle offset for any open ﬁle descriptions associated with the ﬁle. On suc-

cessful completion, if the ﬁle size is changed, these functions will mark for update the st_ctime and

st_mtime ﬁelds of the ﬁle, and if the ﬁle is a regular ﬁle, the

S_ISUID and S_ISGID bits of the ﬁle mode

may be cleared.

RETURN VALUE

Upon successful completion,

ftruncate()and truncate() returns 0. Otherwise a −1 is returned,

and errno is set to indicate the error.

ERRORS

ftruncate() or truncate() fails, errno is set to one of the following values:

[EINTR] A signal was caught during execution.

[EINVAL] The length argument was less than 0.

[EFBIG] or [EINVAL] The length argument was greater than the maximum ﬁle size.

[EIO] An I/O error occurred while reading from or writing to a ﬁle system.

[EAGAIN] Enforcement mode ﬁle/record locking is set (see chmod(2)), and there are

outstanding record locks on the ﬁle with the

lockf(), flock(),or

fcntl() system calls.

ftruncate() fails, errno is set to one of the following values:

[EBADF] or [EINVAL] The ﬁldes argument is not a ﬁle descriptor open for writing.

[EDQUOT] The user’s disk quota block limit has been reached for this ﬁle system.

[EINVAL] The ﬁldes argument references a ﬁle that was opened without write per-

mission.

truncate() fails, errno is set to one of the following values:

[EACCES] A component of the path preﬁx denies search permission, or write permis-

sion is denied on the ﬁle.

[EDQUOT] The user’s disk quota block limit has been reached for this ﬁle system.

[EFAULT] path points outside the process’s allocated address space. The reliable

detection of this error is implementation dependent.

[EISDIR] The named ﬁle is a directory.

[ELOOP] Too many symbolic links were encountered in resolving path .

[ENAMETOOLONG] Pathname resolution produced an intermediate result whose length

exceeds

PATH_MAX bytes, or the length of a component of the pathname

exceeds NAME_MAX bytes.

HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1

Summary of content (2 pages)

PAGE 1
truncate(2) truncate(2) NAME ftruncate, truncate - truncate a file to a specified length SYNOPSIS #include int ftruncate(int fildes, off_t length); int truncate(const char *path, off_t length); DESCRIPTION The ftruncate() function causes the regular file referenced by fildes to have a size of length bytes. The truncate() function causes the regular file named by path to have a size of length bytes. The effect of ftruncate() and truncate() on other types of files is unspecified.
PAGE 2
truncate(2) truncate(2) [ENOENT] A component of path does not name an existing file or path is an empty string. [ENOTDIR] A component of the path prefix of path is not a directory. [EROFS] The named file resides on a read-only file system. [ETXTBSY] The file is a pure procedure (shared text) file that is being executed. AUTHOR truncate() was developed by the University of California, Berkeley.