When invoked without arguments, the
utility displays the contents of the Exif UserComment tag contained in
to the standard output. Otherwise, depending on the options specified,
will blank the tag or set it to
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
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
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.
only displays and writes ASCII character set comments.
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
will blank the comment prior to setting it to
Overwrite or blank existing or unsupported comments without prompting
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.
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
Separate field name and value in the verbose and multiple file cases with
The default is ': '.
Be verbose when printing the contents of the UserComment tag. Besides
the comment itself (if present and supported),
will display the maximum comment length supported, the character code of
the comment, and the length of the comment.
Set UserComment to the ASCII string
is longer than what the tag supports, it will be truncated to fit.
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