Manual: diffstat

DIFFSTAT(1)					User commands					 DIFFSTAT(1)

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 mod‐
       ifications  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 compres‐
       sion 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	 re‐
	      sulting 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 en‐
       vironment 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.	Con‐
       text 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 modi‐
       fied lines for the -m option.

AUTHORS
       Thomas Dickey .

SEE ALSO
       diff(1), patch(1).

1.68						 2025-04-24					 DIFFSTAT(1)