man2/utime.2

   1 .\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
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  25 .\" Modified by Michael Haardt <michael@moria.de>
  26 .\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
  27 .\" Modified 1995-06-10 by Andries Brouwer <aeb@cwi.nl>
  28 .\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
  29 .\" Modified 2004-10-10 by Andries Brouwer <aeb@cwi.nl>
  30 .\"
  31 .TH UTIME 2 2017-09-15 "Linux" "Linux Programmer's Manual"
  32 .SH NAME
  33 utime, utimes \- change file last access and modification times
  34 .SH SYNOPSIS
  35 .nf
  36 .B #include <sys/types.h>
  37 .B #include <utime.h>
  38 .PP
  39 .BI "int utime(const char *" filename ", const struct utimbuf *" times );
  40 .PP
  41 .B #include <sys/time.h>
  42 .PP
  43 .BI "int utimes(const char *" filename ", const struct timeval " times [2]);
  44 .fi
  45 .SH DESCRIPTION
  46 .B Note:
  47 modern applications may prefer to use the interfaces described in
  48 .BR utimensat (2).
  49 .PP
  50 The
  51 .BR utime ()
  52 system call
  53 changes the access and modification times of the inode specified by
  54 .I filename
  55 to the
  56 .IR actime " and " modtime
  57 fields of
  58 .I times
  59 respectively.
  60 .PP
  61 If
  62 .I times
  63 is NULL, then the access and modification times of the file are set
  64 to the current time.
  65 .PP
  66 Changing timestamps is permitted when: either
  67 the process has appropriate privileges,
  68 or the effective user ID equals the user ID
  69 of the file, or
  70 .I times
  71 is NULL and the process has write permission for the file.
  72 .PP
  73 The
  74 .I utimbuf
  75 structure is:
  76 .PP
  77 .in +4n
  78 .EX
  79 struct utimbuf {
  80     time_t actime;       /* access time */
  81     time_t modtime;      /* modification time */
  82 };
  83 .EE
  84 .in
  85 .PP
  86 The
  87 .BR utime ()
  88 system call
  89 allows specification of timestamps with a resolution of 1 second.
  90 .PP
  91 The
  92 .BR utimes ()
  93 system call
  94 is similar, but the
  95 .I times
  96 argument refers to an array rather than a structure.
  97 The elements of this array are
  98 .I timeval
  99 structures, which allow a precision of 1 microsecond for specifying timestamps.
 100 The
 101 .I timeval
 102 structure is:
 103 .PP
 104 .in +4n
 105 .EX
 106 struct timeval {
 107     long tv_sec;        /* seconds */
 108     long tv_usec;       /* microseconds */
 109 };
 110 .EE
 111 .in
 112 .PP
 113 .IR times [0]
 114 specifies the new access time, and
 115 .IR times [1]
 116 specifies the new modification time.
 117 If
 118 .I times
 119 is NULL, then analogously to
 120 .BR utime (),
 121 the access and modification times of the file are
 122 set to the current time.
 123 .SH RETURN VALUE
 124 On success, zero is returned.
 125 On error, \-1 is returned, and
 126 .I errno
 127 is set appropriately.
 128 .SH ERRORS
 129 .TP
 130 .B EACCES
 131 Search permission is denied for one of the directories in
 132 the path prefix of
 133 .I path
 134 (see also
 135 .BR path_resolution (7)).
 136 .TP
 137 .B EACCES
 138 .I times
 139 is NULL,
 140 the caller's effective user ID does not match the owner of the file,
 141 the caller does not have write access to the file,
 142 and the caller is not privileged
 143 (Linux: does not have either the
 144 .B CAP_DAC_OVERRIDE
 145 or the
 146 .B CAP_FOWNER
 147 capability).
 148 .TP
 149 .B ENOENT
 150 .I filename
 151 does not exist.
 152 .TP
 153 .B EPERM
 154 .I times
 155 is not NULL,
 156 the caller's effective UID does not match the owner of the file,
 157 and the caller is not privileged
 158 (Linux: does not have the
 159 .B CAP_FOWNER
 160 capability).
 161 .TP
 162 .B EROFS
 163 .I path
 164 resides on a read-only filesystem.
 165 .SH CONFORMING TO
 166 .BR utime ():
 167 SVr4, POSIX.1-2001.
 168 POSIX.1-2008 marks
 169 .BR utime ()
 170 as obsolete.
 171 .PP
 172 .BR utimes ():
 173 4.3BSD, POSIX.1-2001.
 174 .SH NOTES
 175 Linux does not allow changing the timestamps on an immutable file,
 176 or setting the timestamps to something other than the current time
 177 on an append-only file.
 178 .\"
 179 .\" In libc4 and libc5,
 180 .\" .BR utimes ()
 181 .\" is just a wrapper for
 182 .\" .BR utime ()
 183 .\" and hence does not allow a subsecond resolution.
 184 .SH SEE ALSO
 185 .BR chattr (1),
 186 .BR touch (1),
 187 .BR futimesat (2),
 188 .BR stat (2),
 189 .BR utimensat (2),
 190 .BR futimens (3),
 191 .BR futimes (3),
 192 .BR inode (7)