exifcom(1) [debian man page]
EXIFCOM(1) General Commands Manual EXIFCOM(1) NAME
exifcom - display or set the UserComment tag contained in a JPEG Exif section SYNOPSIS
exifcom [ -bfinv ] [ -w comment ] [ -s delim ] file ... DESCRIPTION
When invoked without arguments, the exifcom utility displays the contents of the Exif UserComment tag contained in file to the standard output. Otherwise, depending on the options specified, exifcom will blank the tag or set it to comment. Some digital cameras include a standard UserComment tag in the Exif data added to the image files they produce. This comment tag is fixed- length and supports multi-byte character sets (though exifcom does not). Note that not all cameras will include the tag. The utility is conservative in its approach to writing the UserComment tag. It does not modify, extend, or otherwise adulterate an image's Exif metadata structure. When writing the tag it merely changes pre-allocated bytes. Therefore, exifcom is at the mercy of the Exif data creator for both the presence of the tag and its length. It cannot create a UserComment tag when the camera does not include one, nor can it write a comment longer than the space pre-allocated by the camera. exifcom only displays and writes ASCII character set comments. OPTIONS
-b Blank the UserComment tag, overwriting both the character code and comment fields with NUL. The character code specifies how the comment is represented; it is "undefined" when blank. This is the state to which many cameras initialize the tag. When used in conjunction with the -w option, exifcom will blank the comment prior to setting it to comment. -f Overwrite or blank existing or unsupported comments without prompting for confirmation. -i Write a prompt to standard error before overwriting or blanking an existing or unsupported comment. If the response from the stan- dard input begins with 'y' or 'Y', the comment is overwritten. This option is default behavior. -n Do not overwrite or blank existing or unsupported comments and do not prompt for confirmation (i.e., automatically answer 'no' to a confirmation prompt). This option takes precedence over both the -f and -i options. -s Separate field name and value in the verbose and multiple file cases with the string delim. The default is ': '. -v Be verbose when printing the contents of the UserComment tag. Besides the comment itself (if present and supported), exifcom will display the maximum comment length supported, the character code of the comment, and the length of the comment. -w Set UserComment to the ASCII string comment. If comment is longer than what the tag supports, it will be truncated to fit. DIAGNOSTICS
The exifcom utility exits 0 on success. When displaying a comment from a single file, if the UserComment tag is missing, it exits 1; if blank, it exits 2; if in an unsupported character code, it exits 3. Otherwise, it exits 1 if an error occurs. SEE ALSO
exiftags(1), exiftime(1) STANDARDS
The exifcom utility was developed using the January 2002 Exif standard, version 2.2 (http://tsc.jeita.or.jp/). BUGS
If the tag doesn't exist or is too short, too bad. AUTHOR
The exifcom utility and this man page were written by Eric M. Johnston <emj@postal.net>. EXIFCOM(1)
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EXIFTIME(1) General Commands Manual EXIFTIME(1) 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 out- put. 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 Cre- ated 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 with- out 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 documenta- tion were derived from portions of FreeBSD's date(1) command by Brian Somers <brian@Awfulhak.org>. EXIFTIME(1)