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DIFFSTAT(1) General Commands Manual 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 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, .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 mark‐
ers 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 differ‐
ences. 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.

-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

-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.

-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 adjust‐
ments.

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 dif‐
ferences 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 differ‐
ences) can be found.

-t overrides the histogram, generates output of comma separated values.

-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
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

However, diffstat assumes that the resulting program uses the same command-line options, e.g., "-c" to decom‐
press 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 a diff file.

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.