UTIME(3) Library Functions Manual UTIME(3)

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 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, , to be updated; see <sys/stat.h>.

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

The utime () function shall fail if:

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.
A loop exists in symbolic links encountered during resolution of the path argument.
The length of the path argument exceeds {PATH_MAX} or a pathname component is longer than {NAME_MAX}.
A component of path does not name an existing file or path is an empty string.
A component of the path prefix is not a directory.
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.
The file system containing the file is read-only.

The utime () function may fail if:

More than {SYMLOOP_MAX} symbolic links were encountered during resolution of the path argument.
As a result of encountering a symbolic link in resolution of the path argument, the length of the substituted pathname string exceeded {PATH_MAX}.

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(3) to retrieve the file's and parameters, set actime and in the buffer, and change one of them before making the utime () call.

None.

The Base Definitions volume of IEEE Std 1003.1-2001 (“POSIX.1”), <sys/stat.h>, <utime.h>

First released in Issue 1. Derived from Issue 1 of the SVID.

The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:

  • The requirement to include <sys/types.h> has been removed. Although <sys/types.h> was required for conforming implementations of previous POSIX specifications, it was not required for UNIX applications.
  • The [ELOOP] mandatory error condition is added.
  • A second [ENAMETOOLONG] is added as an optional error condition.

The following changes were made to align with the IEEE P1003.1a draft standard:

  • The [ELOOP] optional error condition is added.

The DESCRIPTION is updated to avoid use of the term "must" for application requirements.

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December 6, 2001 posix.fail