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exifcom - display or set the UserComment
tag contained in a JPEG Exif section
exifcom [ -bfinv ] [ -w comment
] [ -s delim ] file ...
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.
- -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 standard 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.
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.
exiftags(1)
, exiftime(1)
The exifcom
utility was developed using the January 2002 Exif standard, version 2.2
(http://tsc.jeita.or.jp/).
If the tag doesn't exist or is too short, too
bad.
The exifcom utility and this man page were written by Eric M.
Johnston <emj@postal.net>.
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