TRUNCATE

Section: System Calls (2)
Index Return to Main Contents

BSD mandoc
BSD 4.2

NAME

truncate ftruncate - truncate a file to a specified length

SYNOPSIS

Fd #include <unistd.h> Ft int Fn truncate const char *path off_t length Ft int Fn ftruncate int fd off_t length

DESCRIPTION

Fn Truncate causes the file named by Fa path or referenced by Fa fd to be truncated to at most Fa length bytes in size. If the file previously was larger than this size, the extra data is lost. With Fn ftruncate , the file must be open for writing.

RETURN VALUES

A value of 0 is returned if the call succeeds. If the call fails a -1 is returned, and the global variable errno specifies the error.

ERRORS

Fn Truncate succeeds unless:

Bq Er ENOTDIR: A component of the path prefix is not a directory.
Bq Er ENAMETOOLONG: A component of a pathname exceeded {NAME_MAX} characters, or an entire path name exceeded {PATH_MAX} characters.
Bq Er ENOENT: The named file does not exist.
Bq Er EACCES: Search permission is denied for a component of the path prefix.
Bq Er EACCES: The named file is not writable by the user.
Bq Er ELOOP: Too many symbolic links were encountered in translating the pathname.
Bq Er EISDIR: The named file is a directory.
Bq Er EROFS: The named file resides on a read-only file system.
Bq Er ETXTBSY: The file is a pure procedure (shared text) file that is being executed.
Bq Er EIO: An I/O error occurred updating the inode.
Bq Er EFAULT: Fa Path points outside the process's allocated address space.

Fn Ftruncate succeeds unless:

Bq Er EBADF: The Fa fd is not a valid descriptor.
Bq Er EINVAL: The Fa fd references a socket, not a file.
Bq Er EINVAL: The Fa fd is not open for writing.

BUGS

These calls should be generalized to allow ranges of bytes in a file to be discarded.

HISTORY

The Fn truncate and Fn ftruncate function calls appeared in BSD 4.2

This document was created by man2html, using the manual pages.
Time: 19:41:54 GMT, December 25, 2022