utimes

Name

utimes, lutimes, futimes
- change access and/or modification times of an inode

Library

libc.lib

Synopsis

#include <sys/time.h>

int utimes (const char *path, const struct timeval *times);

int lutimes (const char *path, const struct timeval *times);

int futimes (int fd, const struct timeval *times);

Return values

Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

Detailed description

The access and modification times of the file named by path or referenced by fd are changed as specified by the argument times.

If times is NULL, the access and modification times are set to the current time. The caller must be the owner of the file, have permission to write the file, or be the super-user.

If times is non- NULL, it is assumed to point to an array of two timeval structures. The access time is set to the value of the first element, and the modification time is set to the value of the second element. For file systems that support file birth (creation) times (such as UFS2), the birth time will be set to the value of the second element if the second element is older than the currently set birth time. To set both a birth time and a modification time, two calls are required; the first to set the birth time and the second to set the (presumably newer) modification time. Ideally a new system call will be added that allows the setting of all three times at once. The caller must be the owner of the file or be the super-user.

In either case, the inode-change-time of the file is set to the current time.

The lutimes system call is like utimes except in the case where the named file is a symbolic link, in which case lutimes changes the access and modification times of the link, while utimes changes the times of the file the link references.

Examples

/**
*  Detailed description: Sample usage of utimes system call.
*  Preconditions: Example.txt file should exist in the working directory
**/
#include <sys/types.h>
#include <utime.h>
#include <sys/time.h>
int main()
{
  struct timeval Tim[1] ;
 Tim[0].tv_sec = 0 ;
 Tim[0].tv_usec = 0 ;
  if(utimes("Example.txt"  , Tim) < 0 )
  {
     printf("Utimes system call failed \n") ;
     return -1 ;
  }
  printf("Utimes call succeded \n") ;
 return 0 ;
}

Errors

The utimes and lutimes system calls will fail if:

[`EACCES`]
	Search permission is denied for a component of the path prefix; or the times argument is `NULL` and the effective user ID of the process does not match the owner of the file, and is not the super-user, and write access is denied.
[`EFAULT`]
	The path or times argument points outside the process’s allocated address space.
[`EIO`]	An I/O error occurred while reading or writing the affected inode.
[`ELOOP`]
	Too many symbolic links were encountered in translating the pathname.
[`ENAMETOOLONG`]
	A component of a pathname exceeded `NAME_MAX` characters, or an entire path name exceeded `PATH_MAX` characters.
[`ENOENT`]
	The named file does not exist.
[`ENOTDIR`]
	A component of the path prefix is not a directory.
[`EPERM`]
	The times argument is not `NULL` and the calling process’s effective user ID does not match the owner of the file and is not the super-user.
[`EROFS`]
	The file system containing the file is mounted read-only.

The futimes system call will fail if:

[`EBADF`]
	The fd argument does not refer to a valid descriptor.

All of the system calls will fail if:

[`EACCES`]
	The times argument is `NULL` and the effective user ID of the process does not match the owner of the file, and is not the super-user, and write access is denied.
[`EFAULT`]
	The times argument points outside the process’s allocated address space.
[`EIO`]	An I/O error occurred while reading or writing the affected inode.
[`EPERM`]
	The times argument is not `NULL` and the calling process’s effective user ID does not match the owner of the file and is not the super-user.
[`EROFS`]
	The file system containing the file is mounted read-only.

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