/usr.bin/uuencode/uuencode.format.5

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 28.\"	@(#)uuencode.format.5	8.2 (Berkeley) 1/12/94
 29.\" $FreeBSD$
 30.\"
 31.Dd January 12, 1994
 32.Dt UUENCODE 5
 33.Os
 34.Sh NAME
 35.Nm uuencode
 36.Nd format of an encoded uuencode file
 37.Sh DESCRIPTION
 38Files output by
 39.Xr uuencode 1
 40consist of a header line,
 41followed by a number of body lines,
 42and a trailer line.
 43The
 44.Xr uudecode 1
 45command
 46will ignore any lines preceding the header or
 47following the trailer.
 48Lines preceding a header must not, of course,
 49look like a header.
 50.Pp
 51The header line is distinguished by having the first
 526 characters
 53.Dq begin\ \&
 54(note the trailing space).
 55The word
 56.Em begin
 57is followed by a mode (in octal),
 58and a string which names the remote file.
 59A space separates the three items in the header line.
 60.Pp
 61The body consists of a number of lines, each at most 62 characters
 62long (including the trailing newline).
 63These consist of a character count,
 64followed by encoded characters,
 65followed by a newline.
 66The character count is a single printing character,
 67and represents an integer, the number of bytes
 68the rest of the line represents.
 69Such integers are always in the range from 1 to 45 or 64 and can
 70be determined by subtracting the character space (octal 40)
 71from the character.
 72Character 64 represents a count of zero.
 73.Pp
 74Groups of 3 bytes are stored in 4 characters, 6 bits per character.
 75All characters are always in range from 1 to 64 and are offset by a
 76space (octal 40) to make the characters printing.
 77Character
 7864 represents a count of zero.
 79The last line may be shorter than the normal 45 bytes.
 80If the size is not a multiple of 3, this fact can be determined
 81by the value of the count on the last line.
 82Extra null characters will be included to make the character count a multiple
 83of 4.
 84The body is terminated by a line with a count of zero.
 85This line consists of one
 86.Tn ASCII
 87backquote (octal 140) character.
 88.Pp
 89The trailer line consists of
 90.Dq end
 91on a line by itself.
 92.Sh SEE ALSO
 93.Xr mail 1 ,
 94.Xr uucp 1 ,
 95.Xr uudecode 1 ,
 96.Xr uuencode 1
 97.Sh HISTORY
 98The
 99.Nm
100file format appeared in
101.Bx 4.0 .
102.\" It was named uuencode.5 prior to 4.3