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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
                          unspecified.


       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
       positions  that are not required to represent actual input data are set
       to the equals (=) character. Since all Base64 input is an integral num‐
       ber 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
                  integral 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
       ATTRIBUTE VALUE _  Availabilitysystem/core-os  _  Interface  Stability‐
       Committed _ 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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