Provided by: exiftags_1.01-6_amd64 
NAME
exiftime - display or adjust date & time Exif tags; list files ordered by their Exif date
& time tags
SYNOPSIS
exiftime [-filqw] [-s delim] [-t[acdg]] [-v[+|-]val[ymwdHMS]] file ...
DESCRIPTION
When invoked without arguments, the exiftime utility displays the Exif date and time tags
contained in each input file to the standard output. Otherwise, depending on the options
specified, exiftime will operate on only the chosen tags, will adjust the date and time,
will write an adjusted time to each file, or will list each file in ascending order by
date and time.
Most digital cameras include one or more date and time tags in the Exif data added to the
image files they produce. These tags are:
Image Created
The date and time the image was created or changed. This is the most common tag.
Image Generated
The date and time the original image data was generated (i.e., when picture was
taken).
Image Digitized
The date and time the image was stored as digital data.
The format for these tags is "YYYY:MM:DD HH:MM:SS" with the time shown in 24-hour format.
The exiftime utility cannot add a tag if it does not already exist in file.
By default, exiftime will simply print out any of the three date and time flags in each
input file. The -l flag will produce a listing of each input file in date/time order,
suitable for use in further image processing (e.g., production of a Web catalog) when
filename ordering is not useful.
The -v flag may be used to vary, or adjust, dates and times. When used with the -w flag,
which writes the adjusted date and time to each input file, one may, for example, process
a batch of files to adjust for a camera's incorrectly set clock.
OPTIONS
-f Write adjusted date and time tags without prompting for confirmation.
-i Output a prompt to standard error before overwriting a date and time tag with the
adjusted value. If the response from the standard input begins with 'y' or 'Y',
the tag is overwritten. This option is default behavior.
-l List each input file in ascending order by timestamp. By default, it uses the
Image Created tag. In the absence of an Image Created tag, first Image Generated
then Image Digitized are used. Alternatively, the -t flag may be used to specify
the timestamp preference for ordering. If no date and time tags are present, the
OS's epoch is used. This flag overrides all others but the -t flag.
-q Do not output details of a date and time adjustment to standard out when using the
-w flag.
-s Separate field name and value with the string delim. The default is ': '.
-t Select the date and time tags for display or adjustment when followed by one or
more of a (all tags), c (Image Created), d (Image Digitized), or g (Image
Generated).
-v Adjust the date and time tags' second, minute, hour, month day, week day, month or
year according to val. If val is preceded with a plus or minus sign, the date is
adjusted forwards or backwards according to the remaining string; otherwise the
relevant part of the date is set. The date can be adjusted as many times as
required using these flags. Flags are processed in the order given.
When providing an absolute value (rather than a relative adjustment), seconds are
in the range 0-59, minutes are in the range 0-59, hours are in the range 0-23,
month days are in the range 1-31, week days are in the range 0-6 (Sun-Sat), months
are in the range 1-12 (Jan-Dec) and years are in the range 80-38 or 1980-2038.
If val is numeric, one of either y, m, w, d, H, M, or S must be used to specify
which part of the date is to be adjusted.
The week day or month may be specified using a name rather than a number. If a
name is used with the plus (or minus) sign, the date will be put forwards (or
backwards) to the next (previous) date that matches the given week day or month.
This will not adjust the date, if the given week day or month is the same as the
current one.
When the date is adjusted to a specific value that doesn't actually exist (for
example March 26, 1:30 BST 2000 in the Europe/London timezone), the date will be
silently adjusted forwards in units of one hour until it reaches a valid time.
When the date is adjusted to a specific value that occurs twice (for example
October 29, 1:30 2000), the resulting timezone will be set so that the date matches
the earlier of the two times. In all cases, daylight savings time considerations
are ignored.
Refer to the examples below for further details.
-w Write the adjusted date and time tags. By default, any of the three date and time
tags present in the file are adjusted; otherwise, only those specified with the -t
flag are adjusted.
EXAMPLES
The command
exiftime example1.jpg
will display:
Image Created: 2003:09:12 17:05:37
Image Generated: 2003:09:12 17:05:37
Image Digitized: 2003:09:12 17:05:37
The command
exiftime -tcd example1.jpg
will display:
Image Created: 2003:09:12 17:05:37
Image Digitized: 2003:09:12 17:05:37
The command
exiftime -v+3H example1.jpg
will adjust each time forward by three hours and display:
Image Created: 2003:09:12 20:05:37
Image Generated: 2003:09:12 20:05:37
Image Digitized: 2003:09:12 20:05:37
The command
exiftime -v+5d -v-7M -fw -tg *.jpg
will adjust the date ahead five days and the time back seven minutes and write the
adjusted date and time to the Image Generated tag without a prompt for confirmation for
all files that match "*.jpg". It displays:
example1.jpg:
Image Generated: 2003:09:12 17:05:37 -> 2003:09:17 16:58:37
example2.jpg:
Image Generated: 2004:01:22 17:07:02 -> 2004:01:27 17:00:02
The command
exiftime -l -tdg *.jpg
will list all files that match "*.jpg", one per line, in ascending timestamp order. It'll
attempt to use the following timestamp values, in order: Image Digitized, Image Generated,
Image Created, and, finally, the OS's epoch.
DIAGNOSTICS
The exiftime utility exits 0 on success and 1 if an error occurs.
SEE ALSO
exiftags(1), exifcom(1)
STANDARDS
The exiftime utility was developed using the 2003 draft Exif standard, version 2.21
(http://tsc.jeita.or.jp/).
BUGS
Does not support the Exif tags SubsecTime, SubsecTimeOriginal, or SubsecTimeDigitized.
Does not support manufacturer-specific date and time tags.
AUTHOR
The exiftime utility and this man page were written by Eric M. Johnston <emj@postal.net>.
The time adjustment functionality and documentation were derived from portions of
FreeBSD's date(1) command by Brian Somers <brian@Awfulhak.org>.
EXIFTIME(1)