uuencode, uudecode - encode a binary file, or decode its
uuencode [source-file] decode_pathname
uudecode [-p] [encoded-file]
These commands encode and decode files as follows:
The uuencode utility converts a binary file into an encoded
representation that can be sent using mail(1). It encodes
the contents of source-file, or the standard input if no
source-file argument is given. The decode_pathname argument
is required. The decode_pathname is included in the encoded
file's header as the name of the file into which uudecode is
to place the binary (decoded) data. uuencode also includes
the permission modes of source-file (except setuid, setgid,
and sticky-bits), so that decode_pathname is recreated with
those same permission modes.
The uudecode utility reads an encoded-file, strips off any
leading and trailing lines added by mailer programs, and
recreates the original binary data with the filename and the
mode specified in the header.
The encoded file is an ordinary portable character set text
file; it can be edited by any text editor. It is best only
to change the mode or decode_pathname in the header to
avoid corrupting the decoded binary.
The following option is supported:
-p Decodes encoded-file and sends it to standard output.
This allows uudecode to be used in a pipeline.
The following operands are supported by uuencode and
The pathname of the file into which the uudecode util-
ity will place the decoded file. If there are charac-
ters in decode_pathname that are not in the portable
filename character set the results are unspecified.
A pathname of the file to be encoded.
The pathname of a file containing the output of uuen-
See largefile(5) for the description of the behavior of
uuencode and uudecode when encountering files greater than
or equal to 2 Gbyte ( 2**31 bytes).
See environ(5) for descriptions of the following environment
variables that affect the execution of uuencode and
uudecode: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES, and NLSPATH.
The standard output is a text file (encoded in the character
set of the current locale) that begins with the line:
"begin%s%s\n", <mode>, decode_pathname
and ends with the line:
In both cases, the lines have no preceding or trailing blank
The algorithm that is used for lines in between begin and
end takes three octets as input and writes four characters
of output by splitting the input at six-bit intervals into
four octets, containing data in the lower six bits only.
These octets are converted to characters by adding a value
of 0x20 to each octet, so that each octet is in the range
0x20-0x5f, and then it is assumed to represent a printable
character. It then will be translated into the corresponding
character codes for the codeset in use in the current
locale. (For example, the octet 0x41, representing A , would
be translated to A in the current codeset, such as 0xc1 if
it were EBCDIC.)
Where the bits of two octets are combined, the least signi-
ficant bits of the first octet are shifted left and combined
with the most significant bits of the second octet shifted
right. Thus, the three octets A, B, C are converted into the
0x20 + (( A >> 2 ) & 0x3F)
0x20 + (((A << 4) ((B >> 4) & 0xF)) & 0x3F)
0x20 + (((B << 2) ((C >> 6) & 0x3)) & 0x3F)
0x20 + (( C ) & 0x3F)
These octets are then translated into the local character
Each encoded line contains a length character, equal to the
number of characters to be decoded plus 0x20 translated to
the local character set as described above, followed by the
encoded characters. The maximum number of octets to be
encoded on each line is 45.
The following exit values are returned:
0 Successful completion.
>0 An error occurred.
See attributes(5) for descriptions of the following attri-
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| Availability | SUNWesu |
| Interface Stability | Standard |
mail(1), mailx(1), uucp(1C), uux(1C), attributes(5),
environ(5), largefile(5), standards(5)
The encoded file's size is expanded by 35% (3 bytes become
4, plus control information), causing it to take longer to
transmit than the equivalent binary.
The user on the remote system who is invoking uudecode (typ-
ically uucp) must have write permission on the file speci-
fied in the decode_pathname.
If you invoke uuencode and then execute uudecode on a file
in the same directory, you will overwrite the original file.
Man(1) output converted with