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uuencode

uuencode


  1  definition  found 
 
  From  The  Free  On-line  Dictionary  of  Computing  (13  Mar  01)  [foldoc]: 
 
  uuencode 
 
  Unix  program  for  encoding  binary  data  as  ASCII.  Uuencode  was 
  originally  used  with  uucp  to  transfer  binary  files  over  serial 
  lines  which  did  not  preserve  the  top  bit  of  characters  but  is 
  now  used  for  sending  binary  files  by  e-mail  and  posting  to 
  {Usenet}  newsgroups  etc  The  program  uudecode  reverses  the 
  effect  of  uuencode,  recreating  the  original  binary  file 
  exactly. 
 
  Uuencoded  data  starts  with  a  line  of  the  form 
 
  begin     
 
  where    is  the  files  read/write/execute  permissions  as 
  three  {octal}  digits  and    is  the  name  to  be  used  when 
  recreating  the  binary  data. 
 
  Uuencode  repeatedly  takes  in  a  group  of  three  bytes,  adding 
  trailing  zeros  if  there  are  less  than  three  bytes  left 
  These  24  bits  are  split  into  four  groups  of  six  which  are 
  treated  as  numbers  between  0  and  63.  Decimal  32  is  added  to 
  each  number  and  they  are  ouput  as  ASCII  characters  which  will 
  lie  in  the  range  32  (space)  to  32+63  =  95  (underscore).  Each 
  group  of  sixty  ouptut  characters  (corresponding  to  45  input 
  bytes)  is  output  as  a  separate  line  preceded  by  an  'M'  (ASCII 
  code  77  =  32+45).  At  the  end  of  the  input,  if  there  are  N 
  output  characters  left  after  the  last  group  of  sixty  and  N>0 
  then  they  will  be  preceded  by  the  character  whose  code  is 
  32+N.  Finally,  a  line  containing  just  a  single  space  is 
  output,  followed  by  one  containing  just  "end". 
 
  Sometimes  each  data  line  has  an  extra  dummy  character  added  to 
  avoid  problems  which  mailers  that  strip  trailing  spaces. 
  These  characters  are  ignored  by  uudecode. 
 
  Despite  using  this  limited  range  of  characters,  there  are 
  still  some  problems  encountered  when  uuencoded  data  passes 
  through  certain  old  computers.  The  worst  offenders  are 
  computers  using  non-ASCII  character  sets  such  as  EBCDIC.