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 num-
ber 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 sepa-
rates 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, followed by a newline. The character
count is a single printing character, and represents an integer, the num-
ber of bytes the rest of the line represents. Such integers are always
in the range from 0 to 63 and can be determined by subtracting the char-
acter space (octal 40) from the character.
Groups of 3 bytes are stored in 4 characters, 6 bits per character. All
are offset by a space to make the characters printing. 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 garbage 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 ` (opening single quote) character.
The trailer line consists of ``end'' on a line by itself.
mail(1), uudecode(1), uuencode(1)
The uuencode file format appeared in 4.0BSD.
BSD May 29, 2017 BSD