man > UUENCODE(5)

UUENCODE(5)                              File Formats Manual                             UUENCODE(5)

NAME
       uuencode - format of an encoded uuencode file

DESCRIPTION
       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 fol‐
       lowing the trailer.  Lines preceding a header must not, of course, look like a header.

       The header line is distinguished by having the first 5 characters  be  begin  followed  by  a
       space,  or else a hyphen and either base64 or encoded or both (also separated with a hyphen).
       The base64 option says the file has been encoded using base64.  The encoded option  says  the
       output  file  name has been base64 encoded.  It is never encoded with traditional uuencoding.
       This is a GNU extension.  These are followed by a mode (in octal), and a string  which  names
       the  remote  file.  The mode is separated from the begin clause and the file name by a single
       space character.

   Traditional uuencoding
       The traditional uuencoded file body consists of a number of lines, each at most 62 characters
       long (including the trailing newline). These consist of a character count letter, followed by
       the encoded characters, followed 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 0 to 63 and can be determined by  subtracting  the
       character 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  multi‐
       ple  of 4.  The body is terminated by a line with a count of zero.  This line consists of one
       ASCII space.

       The trailer line consists of end on a line by itself.

   base64 encoding
       base64 encoded files follow the specified format for the body,  but  also  include  a  begin-
       base64 header and a trailer line of four = characters.

EXAMPLES
            begin-base64-encoded 644 VE9ETw==
       This  introduces a base64 encoded file named, TODO with that name encoded using base64 encod‐
       ing.

            begin-encoded 644 5$]$3P``
       This introduces an encoded file named, TODO with that name encoded using uuencoding.  The en‐
       coding is a lot less friendly.  Please prefer base64 encoding.

CONFORMING TO
       IEEE Std 1003.1, plus extensions

       The -encoded suffix to the begin header line is a GNU extension.  Recipients  must  have  the
       GNU uudecode program to decode them.

SEE ALSO
       uuencode(1), uudecode(1), base64(1GNU)

HISTORY
       The uuencode file format appeared in BSD 4.0 .

                                                                                         UUENCODE(5)