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 modifications per-
       file.  Diffstat is a program that is useful for reviewing large, complex patch files.  It reads from one or more	 in‐
       put 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 uncom‐
       pressed 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	his‐
       togram 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	 ob‐
	      tain 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 in‐
	      ferring 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 path‐
	      names.  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 termi‐
	      nal'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  vari‐
       ables 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 .

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

1.68							 2025-04-24						 DIFFSTAT(1)