DSORT(1)                   Commands and Applications                  DSORT(1)

NAME

       dsort, msort - sort text files lexicographically

SYNOPSIS

       msort [ -hvV?  ] [ -o outfile ] [ -n lines ] file1 [ file2 ...  ]

       dsort  [  -hvV?   ]  [  -l  length  ]  [  -n lines ] [ -o outfile ] [-t
       path1[,path2[,path3[,path4]]]] infile

DESCRIPTION

       This manual page documents dsort and msort version 1.0.

       dsort and msort are robust text file sorting utilities.  While they  do
       not  support  a  lot  of features, they are designed to sort large (and
       small) files very quickly.

       msort is an in-place memory sort.  Since it  uses  the  heapsort  algo‐
       rithm, it is O[n lg n] both on average and for worst-case.  Provided it
       has enough memory, msort  will  sort  files  with  lines  of  arbitrary
       length.   Unless overridden by the -n flag, msort will sort files of up
       to 1000 lines.  Larger files can be sorted provided there is sufficient
       core memory.  If multiple input files are given, the output is the con‐
       catenated result of sorting the input files separately.  Thus, the fol‐
       lowing would be equivalent:

              % msort file1 file2 file3 >outfile
       and
              % msort file1 >file1out
              % msort file2 >file2out
              % cat file1out file2out >outfile

       dsort  is a disk sort intended for files too large to be sorted in mem‐
       ory.  It uses a four-file polyphase merge algorithm.  Since  it  is  an
       I/O-bound  program, dsort's speed is very dependant on the speed of the
       device used for temporary files.  By default,  dsort  will  sort  files
       with  lines up to 512 characters long.  Lines with more characters will
       be trucated unless the -l flag is used.  Also by default, 1000 lines at
       a  time will be sorted in memory during the collection (first) phase of
       the merge sort algorithm.  This can  be  changed  using  the  -n  flag.
       dsort will accept only one input file.

       Both dsort and msort leave the input file(s) intact.

OPTIONS

       -h -?         -- print version and usage info, then exit
       -l length     -- use a line length of length
       -n lines      -- sort lines lines in memory, (for dsort); don't
                        try to sort files over lines long (for msort).
       -o outfile    -- send sorted output to outfile rather than to stdout
       -t pathlist   -- use pathlist as the locations of temp files.  If any
                        of these are not specified, dsort will attempt to use
                        the directory specified by the environment variable
                        $(TMPDIR), then the system default temp path.
       -v            -- verbose operation
       -V            -- print version information

HINTS

       If you have more than one fast drive, the speed of dsort can in general
       be improved by using four different drives for the path list when using
       -t  .  The best speed observed, however, has occurred when $(TMPDIR) or
       /tmp reside on a RAM disk or ROM disk.  It is not suggested that  flop‐
       pies be used for temporary files.

RESOURCE USAGE

       Both dsort and msort use 1k of stack space.

       msort is an in-place sort, so in general the amount of core memory used
       is the same as the size of the file to be sorted.  When sorting  multi‐
       ple  files, msort's memory usage will match the size of the largest in‐
       put file, not the total of all files.  It will use a minimum of approx‐
       imately 4k of core memory.

       dsort  by  default uses approximately 512k of core memory.  This can be
       modified by changing the -l and -n parameters.  Core  memory  usage  is
       approximately the product of these two parameters.

       When  using  dsort, the amount free space on the temporary path(s) must
       be at least twice the size of the file to be sorted.

AUTHOR

       Devin Reade - glyn@cs.ualberta.ca

SEE ALSO

       sort(1), uniq(1).



GNO                              14 June 1994                         DSORT(1)