On 9/17/05, m ike <[EMAIL PROTECTED]> wrote:
> i am suprised that grep reported that it found matches within the first two
> lines that you've pasted, and i am suprised that hexdump -C is not showing
> ff d8 as the initial two bytes of the cat'd file.

Oh.  Uh...  *slaps forehead*  I deleted a bit of the beginning hex on
those lines, to save some space.  That's why you didn't see ff d8 as
the initial two bytes.

So, I made a new cat'd together jpg glob.  I used photos taken from a
digital camera, so they surely have exif data in them.  I did:

# cat photo* > smooshed-jpgs
# hexdump -C smooshed-jpgs | grep -e "\ ff\ d8\
\|[0-9]:[0-9][0-9]\|[0-9][0-9]:[0-9]" > CF_grepped_hexdump
# cat CF_grepped_hexdump

and I got:

00000000  ff d8 ff e0 00 10 4a 46  49 46 00 01 01 00 00 01  |......JFIF......|
00010090  c5 63 ff d9 ff d8 ff e0  00 10 4a 46 49 46 00 01  |.c........JFIF..|
000217f0  d9 ff d8 ff e0 00 10 4a  46 49 46 00 01 01 00 00  |.......JFIF.....|
00030750  76 e8 76 ce ad 3a 91 52  b5 a5 d4 ff d9 ff d8 ff  |v.v..:.R........|

and so on...

Every line has an 'ff d8' or 'ff d9', but none have date/time info. 
Surely the camera makes a timestamp!  And also, printf doesn't like
those leading offsets. ' printf "%d" 00010090 ' gives me "bash:
printf: 00010090: invalid number".

I don't understand printf (a C function, yeah?), so I don't know what it wants.

-todd


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