utime - set file access and modification times

#include <utime.h>

int utime(const char *path, const struct utimbuf *times);

The utime() function shall set the access and modification times of the file named by the path argument.

If times is a null pointer, the access and modification times of the file shall be set to the current time. The effective user ID of the process shall match the owner of the file, or the process has write permission to the file or has appropriate privileges, to use utime() in this manner.

If times is not a null pointer, times shall be interpreted as a pointer to a utimbuf structure and the access and modification times shall be set to the values contained in the designated structure. Only a process with the effective user ID equal to the user ID of the file or a process with appropriate privileges may use utime() this way.

The utimbuf structure is defined in the <utime.h> header. The times in the structure utimbuf are measured in seconds since the Epoch.

Upon successful completion, utime() shall mark the time of the last file status change, st_ctime, to be updated; see <sys/stat.h>.

Upon successful completion, 0 shall be returned. Otherwise, -1 shall be returned and errno shall be set to indicate the error, and the file times shall not be affected.

The utime() function shall fail if:

EACCES

Search permission is denied by a component of the path prefix; or the times argument is a null pointer and the effective user ID of the process does not match the owner of the file, the process does not have write permission for the file, and the process does not have appropriate privileges.

ELOOP

A loop exists in symbolic links encountered during resolution of the path argument.

ENAMETOOLONG

The length of the path argument exceeds {PATH_MAX} or a pathname component is longer than {NAME_MAX}.

ENOENT

A component of path does not name an existing file or path is an empty string.

ENOTDIR

A component of the path prefix is not a directory.

EPERM

The times argument is not a null pointer and the calling process' effective user ID does not match the owner of the file and the calling process does not have the appropriate privileges.

EROFS

The file system containing the file is read-only.

The utime() function may fail if:

ELOOP

More than {SYMLOOP_MAX} symbolic links were encountered during resolution of the path argument.

ENAMETOOLONG

As a result of encountering a symbolic link in resolution of the path argument, the length of the substituted pathname string exceeded {PATH_MAX}.

The following sections are informative.

None.

None.

The actime structure member must be present so that an application may set it, even though an implementation may ignore it and not change the access time on the file. If an application intends to leave one of the times of a file unchanged while changing the other, it should use stat() to retrieve the file's st_atime and st_mtime parameters, set actime and modtime in the buffer, and change one of them before making the utime() call.

None.

The Base Definitions volume of IEEE Std 1003.1-2001, <sys/stat.h>, <utime.h>

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .