Unshar

     UNSHAR V1.3(1)        AMIGA Programmer's Manual         UNSHAR V1.3(1)

     NAME 
          unshar - extracts files from shar archives 

     SYNOPSIS 
          unshar {-overwrite} {-nosort} file1 file2 ...  

     DESCRIPTION 
          Unshar is a utility which extracts files from the ubiquitous
          Unix shar  archives.    It has the following advantages over
          existing unshar utilities: 

               - Small and fast 
               - Handles many cat and sed formats 
               - Allows extraction of subdirectories 
               - Understands ./file type filenames 
               - Understands file continuation with >> 
               - Sorts file list by Subject: line 
               - Exits cleanly with CTRL-C 

          The total code size is slightly  over  5K,  for  those  with
          packed C  directories.  It treats quotes and imbedded escape
          sequences intelligently and handles  all  the  cat  and  sed
          formats  I've  ever seen, including sed commands which strip
          off more than one letter.  There  may  be  some  formats  it
          won't handle, but I've yet to find them.  

          Invoke  unshar  with  as many archive filenames as you like.
          All the files in each archive will  be  extracted  into  the
          current directory.    If  a file already exists, unshar asks
          you how you want to handle it.  Entering `Y' will  overwrite
          the  existing file with the version in the archive, `N' will
          skip past the file  without  extracting  it,  and  `A'  will
          overwrite  this  file  and  any other existing files without
          prompting you again.  Including the -o flag on  the  command
          line causes files to always be overwritten.  

     OPERATION 
          ›0mUnshar  scans  through each archive specified on the command
          line, looking for lines beginning with `cat' or  `sed'.  All
          other lines  are  ignored.   In particular, `echo' lines are
          not echoed.  This way, you don't  get  a  load  of  messages
          which  are  in  any  case  fairly  meaningless,  because the
          operations they are describing are unsupported.  

          When a shar  archive  contains  a  file  for  which  a  full
          pathname  is  given (as in source/file.c for example) unshar
          will create whatever directories are  necessary.    It  also
          strips   off   leading  /'s  and  ./'s,  to  make  filenames
          understandable by AmigaDOS.  

          Occasionally, a shar file distribution will contain  a  file
          too  large  to  fit into a single shar archive (archives are
          typically limited to around 60K or so for transmission  over
          Usenet). One method some archivers use to get around this is
          to  split the large file into several smaller parts, and use
          the shell `>>' redirection operator to concatenate the parts
          together while extracting the files.  In order for  this  to


     Copyright Eddy Carroll 1990      -1-


     UNSHAR V1.3(1)        AMIGA Programmer's Manual         UNSHAR V1.3(1)


          work  properly,  it  is important that the archive files are
          extracted in the correct sequence; otherwise, all the pieces
          will get joined together in the wrong order.  

          To assist with this, unshar does  a  prescan  over  all  the
          files listed on the command line, and checks each file for a
          "Subject:" line.    If  it  finds  such  a line, it scans it
          looking for any hints as to where  the  file  comes  in  the
          sequence.   Most  shar  files  you  feed  to  unshar will be
          directly from a Usenet sources or binaries group,  and  will
          include  a  volume  and issue reference on the subject line.
          If unshar can't find such an issue reference, it  will  look
          for a Part number and use that instead.  

          Unshar  then  extracts the archives starting with the lowest
          numbered file.  This helps to ensure that those  extra-large
          files are  created correctly.  You can tell when such a file
          is being  created,  because  unshar  says  "Extending  file"
          rather than "Unsharing file".  

          If  for  some  reason you want the files to be unarchived in
          the order listed on the command line, you  can  specify  the
          `-n' (nosort) switch, and no sorting will take place.  

     DISTRIBUTION 
          ›0mUnshar  may  be  freely distributed, as long as no charge is
          made for doing so.  

     HISTORY 
          V1.0  First release.  

          V1.1  Added support for some more unusual uses of sed.  
                Increased speed, and reduced size slightly.  
                Fixed bug that truncated lines longer than 80 chars.  

          V1.2  Added support for sorting by Subject: line 
                Added support for file appending via >> 
                Fixed small bug in detection of disk write errors 

          V1.3  Fixed bug in "Overwrite (Yes, [No], All)?" prompt.  
                No longer exits immediately on file read error.  
                Fixed subtle bug in code to skip existing files.  

     AUTHOR 
          Eddy Carroll 
          EMAIL: ecarroll vax1 tcd ie 

     Copyright Eddy Carroll 1990      -2-