NAME

       diffstat - make histogram from diff-output

SYNOPSIS

       diffstat [options] [file-specifications]

DESCRIPTION

       This  program  reads  the  output  of  diff  and  displays  a histogram of the insertions,
       deletions, and modifications per-file.  Diffstat is a program that is useful for reviewing
       large,  complex  patch  files.  It reads from one or more input files which contain output
       from diff, producing a histogram of the total lines changed for each file referenced.

       If the input filename ends with “.bz2”, “.gz”,  “.lzma”,  “.xz”,  “.zst”,  “.z”  or  “.Z”,
       diffstat  will  read  the uncompressed data via a pipe from the corresponding program.  It
       also can infer the compression type from files piped via the standard input.

       Diffstat recognizes the most popular types of output from diff:

          unified
                 preferred by the patch utility.

          context
                 best for readability, but not very compact.

          default
                 not good for much, but simple to generate.

       Diffstat detects the lines that are output by diff to tell which files are  compared,  and
       then  counts  the  markers  in the first column that denote the type of change (insertion,
       deletion or modification).  These  are  shown  in  the  histogram  as  "+",  "-"  and  "!"
       characters.

       If  no  filename  is  given  on  the command line, diffstat reads the differences from the
       standard input.

OPTIONS

       -b     ignore lines matching "Binary files XXX and YYY differ" in the diff

       -c     prefix each line of output with "#", making it a comment-line for shell scripts.

       -C     add SGR color escape sequences to highlight the histogram.

       -D destination
              specify a directory containing files which can be referred  to  as  the  result  of
              applying the differences.  diffstat will count the lines in the corresponding files
              (after adjusting the names by the -p option) to obtain the total number of lines in
              each file.

              The remainder, after subtracting modified and deleted lines, is shown as "unchanged
              lines".

       -d     The debug prints a lot of information.  It is  normally  compiled-in,  but  can  be
              suppressed.

       -e file
              redirect standard error to file.

       -E     strip  out ANSI escape sequences on each line before parsing the differences.  This
              allows diffstat to be used with colordiff.

       -f format
              specify the format of the histogram.

              0  for concise, which shows only the value and a single histogram code for each  of
                 insert (+), delete (-) or modify (!)

              1  for normal output,

              2  to fill in the histogram with dots,

              4  to print each value with the histogram.

              Any  nonzero  value  gives  a  histogram.   The  dots  and individual values can be
              combined, e.g., -f6 gives both.

       -h     prints the usage message and exits.

       -k     suppress the merging of filenames in the report.

       -K     attempt to improve the annotation of "only" files by looking for  a  match  in  the
              resulting set of files and inferring whether the file was added or removed.

              This does not currently work in combination with -R because diffstat maintains only
              the resulting set of files.

       -l     lists only the filenames.  No histogram is generated.

       -m     merge insert/delete counts from each "chunk" of the patch  file  to  approximate  a
              count of the modified lines.

       -n number
              specify the minimum width used for filenames.  If you do not specify this, diffstat
              uses the length of the longest filename, after stripping common prefixes.

       -N number
              specify the maximum width used for filenames.  Names longer  than  this  limit  are
              truncated  on  the  left.   If you do not specify this, diffstat next checks the -n
              option.

       -o file
              redirect standard output to file.

       -p number
              override the logic that strips common pathnames, simulating the patch "-p" option.

              If you do not give a -p option, diffstat examines the differences  and  strips  the
              common prefix from the pathnames.  This is not what patch does.

       -q     suppress the "0 files changed" message for empty diffs.

       -r  code
              provides  optional  rounding of the data shown in histogram, rather than truncating
              with error adjustments.

              0  is the default.  No rounding is performed, but accumulated errors are  added  to
                 following columns.

              1  rounds the data

              2  rounds  the  data and adjusts the histogram to ensure that it displays something
                 if there are any differences even if those would normally be rounded to zero.

       -R     Assume patch was created with old and new files swapped.

       -s     show only the summary line, e.g., number of insertions and deletions.

       -S source
              this is like the -D option, but specifies  a  location  where  the  original  files
              (before applying differences) can be found.

       -t     overrides  the histogram, generates output of comma separated values for the number
              of changed lines found in the differences for  each  file:  inserted,  deleted  and
              modified.

              If -S or -D options are given, the number of unchanged lines precedes the number of
              changes.

       -T     prints the numbers that  the  -t  option  would  show,  between  the  pathname  and
              histogram.

              The width of the number of changes is determined by the largest value (but at least
              3).  The width given in the -w option is separate from the width of these numbers.

       -u     suppress the sorting of filenames in the report.

       -v     show progress, e.g., if the output is redirected to a file, write progress messages
              to the standard error.

       -V     prints the current version number and exits.

       -w number
              specify  the  maximum  width of the histogram.  The histogram will never be shorter
              than 10 columns, just in case the filenames get too large.

              The default is 80 columns, unless the output is to a terminal.  In that  case,  the
              default width is the terminal's width.

ENVIRONMENT

       Diffstat runs in a POSIX environment.

       You  can  override the compiled-in paths of programs used for decompressing input files by
       setting environment variables corresponding to their name:

              DIFFSTAT_BZCAT_PATH
              DIFFSTAT_BZIP2_PATH
              DIFFSTAT_COMPRESS_PATH
              DIFFSTAT_GZIP_PATH
              DIFFSTAT_LZCAT_PATH
              DIFFSTAT_PCAT_PATH
              DIFFSTAT_UNCOMPRESS_PATH
              DIFFSTAT_XZ_PATH
              DIFFSTAT_ZCAT_PATH
              DIFFSTAT_ZSTD_PATH

       However, diffstat assumes that the resulting program uses the same  command-line  options,
       e.g., "-c" to decompress to the standard output.

FILES

       Diffstat is a single binary module, which uses no auxiliary files.

BUGS

       Diffstat makes a lot of assumptions about the format of diff's output.

       There  is  no  way  to  obtain a filename from the standard diff between two files with no
       options.  Context diffs work, as well as unified diffs.

       There's no easy way to determine the degree of overlap between the  "before"  and  "after"
       displays  of  modified  lines.   diffstat simply counts the number of inserted and deleted
       lines to approximate modified lines for the -m option.

AUTHORS

       Thomas Dickey <dickey@invisible-island.net>.

SEE ALSO

       diff(1), patch(1).