If the jpg image doesn't have exif header you need to create it first:
jhead -mkexif
Then enter the time stamp data:
jhead -ts2009:08:15-10:30:00
To determine the file type of the file "sample.txt" you just type:
file sample.txt
Usually it'll tell you only that it is a text file. To get to know more about the encoding type:
enca -L none sample.text
The -L switch tells the program what language is used in the file. If you don't know, just use none.
To convert the encoding from ISO-8859-1 (latin1) to UTF-8:
iconv --from-code=ISO-8859-1 --to-code=UTF-8 sample_iso8859-1.txt > sample_utf-8.txt
I recursively screwed up the file permissions in my html servers root directory. To fix it I needed to deploy some "advanced" chmod settings. Obviously I want to treat directories and files differently. I didn't come up with a better solution than the following:
chmod -R u=rw-x,g=rw-x,o=r-wx *
chmod -R a+X *