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uuencode(1c)

uuencode(1C)                Communication Commands                uuencode(1C)

NAME
       uuencode, uudecode - encode a binary file, or decode its encoded repre‐
       sentation

SYNOPSIS
       uuencode [source-file] decode_pathname


       uuencode [-m] [source-file] decode_pathname


       uudecode [-p] [encoded-file]


       uudecode [-o outfile] [encoded-file]

DESCRIPTION
       These commands encode and decode files as follows:

   uuencode
       The uuencode utility converts a binary file into an encoded representa‐
       tion 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 uude‐
       code 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 re-created with those same permission
       modes.

   uudecode
       The uudecode utility reads an encoded-file, strips off any leading  and
       trailing  lines  added  by mailer programs, and re-creates 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.

OPTIONS
       The following options are supported:

   uuencode
       -m    Encodes  source-file  using Base64 encoding and sends it to stan‐
             dard output.


   uudecode
       -o outfile    Specifies a file pathname that should be used instead  of
                     any  pathname  contained in the input data. Specifying an
                     outfile option-argument of /dev/stdout indicates standard
                     output. This allows uudecode to be used in a pipeline.


       -p            Decodes encoded-file and sends  it  to  standard  output.
                     This allows uudecode to be used in a pipeline.


OPERANDS
       The following operands are supported by uuencode and uudecode:

   uuencode
       decode_pathname    The  pathname  of  the  file into which the uudecode
                          utility will place the decoded file.  If  there  are
                          characters  in  decode_pathname  that are not in the
                          portable filename character set, the results are un‐
                          specified.


       source-file        A pathname of the file to be encoded.


   uudecode
       encoded-file    The pathname of a file containing the output  of  uuen‐
                       code.


ENVIRONMENT VARIABLES
       See  environ(7) for descriptions of the following environment variables
       that affect the execution  of  uuencode  and  uudecode:  LANG,  LC_ALL,
       LC_CTYPE, LC_MESSAGES, and NLSPATH.

OUTPUT
       stdout

   uuencode Base64 Algorithm
       The standard output is a text file, encoded in the character set of the
       current locale, that begins with the line:

         begin-base64 %s %s\n, mode, decode_pathname



       and ends with the line:

         ====\n



       In  both  cases,  the lines have no preceding or trailing blank charac‐
       ters.


       The encoding process represents 24-bit groups of input bits  as  output
       strings  of  four  encoded characters. Proceeding from left to right, a
       24-bit input group is formed by concatenating three 8-bit input groups.
       Each 24-bit input group is then  treated  as  four  concatenated  6-bit
       groups,  each  of which is translated into a single digit in the Base64
       alphabet. When encoding a bit stream by means of the  Base64  encoding,
       the  bit stream is presumed to be ordered with the most-significant bit
       first. That is, the first bit in the stream is the  high-order  bit  in
       the  first  byte,  and the eighth bit is the low-order bit in the first
       byte, and so on. Each 6-bit group is used as an index into an array  of
       64 printable characters, as shown in the following table.

         Value Encoding   Value Encoding   Value Encoding   Value Encoding
           0      A         17     R         34     i         51     z
           1      B         18     S         35     j         52     0
           2      C         19     T         36     k         53     1
           3      D         20     U         37     l         54     2
           4      E         21     V         38     m         55     3
           5      F         22     W         39     n         56     4
           6      G         23     X         40     o         57     5
           7      H         24     Y         41     p         58     6
           8      I         25     Z         42     q         59     7
           9      J         26     a         43     r         60     8
          10      K         27     b         44     s         61     9
          11      L         28     c         45     t         62     +
          12      M         29     d         46     u         63     /
          13      N         30     e         47     v
          14      O         31     f         48     w        (pad)   =
          15      P         32     g         49     x
          16      Q         33     h         50     y



       The character referenced by the index is placed in the output string.


       The  output  stream  (encoded bytes) is represented in lines of no more
       than 76 characters each. All line breaks or other characters not  found
       in the table are ignored by decoding software (see uudecode).


       Special  processing is performed if fewer than 24 bits are available at
       the end of a message or encapsulated part of a message. A full encoding
       quantum is always completed at the end of a message. When fewer than 24
       input bits are available in an input group, zero bits are added on  the
       right  to form an integral number of 6-bit groups. Output character po‐
       sitions that are not required to represent actual input data are set to
       the equals (=) character. Since all Base64 input is an integral  number
       of octets, only the following cases can arise:

           1.     The  final quantum of encoding input is an integral multiple
                  of 24 bits. Here, the final unit of encoded output is an in‐
                  tegral multiple of four characters with no '= ' padding.


           2.     The final quantum of encoding  input  is  exactly  16  bits.
                  Here,  the  final unit of encoded output is three characters
                  followed by one '=' padding character.


           3.     The final quantum of encoding input is exactly 8 bits. Here,
                  the final unit of encoded output is two characters  followed
                  by two '=' padding characters.




       A  terminating  "===="  evaluates to nothing and denotes the end of the
       encoded data.

   uuencode Historical Algorithm
       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:

         end\n



       In both cases, the lines have no preceding or  trailing  blank  charac‐
       ters.


       The  algorithm that is used for lines 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  each octet is assumed to represent a printable charac‐
       ter. Each octet is then 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 the codeset were EBCDIC.


       Where the bits of two octets are combined, the least  significant  bits
       of the first octet are shifted left and combined with the most signifi‐
       cant  bits of the second octet shifted right. Thus, the three octets A,
       B, C are converted into the four octets:

         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 set.


       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.

EXIT STATUS
       The following exit values are returned:

       0     Successful completion.


       >0    An error occurred.


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:

       tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) ATTRIBUTE TYPE AT‐
       TRIBUTE VALUE _ Availabilitysystem/core-os _ Interface StabilityCommit‐
       ted _ StandardSee standards(7).


SEE ALSO
       mail(1), mailx(1), attributes(7), environ(7), standards(7)

NOTES
       The size of the encoded file 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 must have write
       permission on the file specified 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.

Oracle Solaris 11.4               11 May 2021                     uuencode(1C)
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