UUENCODE(5) BSD File Formats Manual UUENCODE(5)
uuencode -- format of an encoded uuencode file
Files output by uuencode(1) consist of a header line, followed by a number of body lines,
and a trailer line. The uudecode(1) command will ignore any lines preceding the header or
following the trailer. Lines preceding a header must not, of course, look like a header.
The header line is distinguished by having the first 6 characters ``begin '' (note the
trailing space). The word begin is followed by a mode (in octal), and a string which names
the remote file. A space separates the three items in the header line.
The body consists of a number of lines, each at most 62 characters long (including the
trailing newline). These consist of a character count, followed by encoded characters, fol-
lowed by a newline. The character count is a single printing character, and represents an
integer, the number of bytes the rest of the line represents. Such integers are always in
the range from 1 to 45 or 64 and can be determined by subtracting the character space (octal
40) from the character. Character 64 represents a count of zero.
Groups of 3 bytes are stored in 4 characters, 6 bits per character. All characters are
always in range from 1 to 64 and are offset by a space (octal 40) to make the characters
printing. Character 64 represents a count of zero. The last line may be shorter than the
normal 45 bytes. If the size is not a multiple of 3, this fact can be determined by the
value of the count on the last line. Extra null characters will be included to make the
character count a multiple of 4. The body is terminated by a line with a count of zero.
This line consists of one ASCII backquote (octal 140) character.
The trailer line consists of ``end'' on a line by itself.
mail(1) , uucp(1) , uudecode(1) , uuencode(1)
The uuencode file format appeared in 4.0BSD.
BSD January 12, 1994 BSD