Using git diff, how can I get added and modified lines numbers?

Question

Assuming I have a text file

alex
bob
matrix
will be removed
git repo

and I have updated it to be

alex
new line here
another         


        

Answer 1

Here's some Python copypasta to get the line numbers for modified / removed lines, in case you came across this question looking for that.

It should be fairly easy to modify it into something that gets the modified and added line numbers as well.

I've only tested on Windows, but it should be cross platform as well.

import re
import subprocess

def main(file1: str, file2: str):
    diff = get_git_diff(file1, file2)
    print(edited_lines(diff))

def edited_lines(git_diff: str):
    ans = []
    diff_lines = git_diff.split("\n")
    found_first = False
    # adjust for added lines
    adjust = 0
    # how many lines since the start
    count = 0
    for line in diff_lines:
        if found_first:
            count += 1
            if line.startswith('-'):
                # minus one because count is 1 when we're looking at the start line
                ans.append(start + count - adjust - 1)
                continue

            if line.startswith('+'):
                adjust += 1
                continue

        # get the start line
        match = re.fullmatch(r'@@ \-(\d+),\d+ \+\d+,\d+ @@', line)
        if match:
            start = int(match.group(1))
            count = 0
            adjust = 0
            found_first = True

    return ans


def get_git_diff(file1: str, file2: str):
    try:
        diff_process: subprocess.CompletedProcess = subprocess.run(['git', 'diff', '--no-index', '-u', file1, file2], shell=True, check=True, stdout=subprocess.PIPE)
        ans = diff_process.stdout
    # git may exit with 1 even though it worked
    except subprocess.CalledProcessError as e:
        if e.stdout and e.stderr is None:
            ans = e.stdout
        else:
            raise

    # remove carriage at the end of lines from Windows
    ans = ans.decode()
    ans.replace('\r', '')
    return ans


if __name__ == "__main__":
    main("file1.txt", "file2.txt")

Answer 2

Line numbers of all uncommitted lines (added/modified):

git blame <file> | grep -n '^0\{8\} ' | cut -f1 -d:

Example output:

1
2
8
12
13
14

Answer 3

This is probably a fairly accurate count of changed lines:

git diff --word-diff <commit> |egrep '(?:\[-)|(?:\{\+)' |wc -l

Also, here is a solution for line numbers in your diff: https://github.com/jay/showlinenum

Answer 4

I had this same problem so I wrote a gawk script that changes the output of git diff to prepend the line number for each line. I find it useful sometimes when I need to diff working tree, although it's not limited to that. Maybe it is useful to someone here?

$ git diff HEAD~1 |showlinenum.awk
diff --git a/doc.txt b/doc.txt
index fae6176..6ca8c26 100644
--- a/doc.txt
+++ b/doc.txt
@@ -1,3 +1,3 @@
1: red
2: blue
 :-green
3:+yellow

You can download it from here:
https://github.com/jay/showlinenum

Answer 5

Here's a bash function to calculate the resulting line numbers from a diff:

diff-lines() {
    local path=
    local line=
    while read; do
        esc=$'\033'
        if [[ $REPLY =~ ---\ (a/)?.* ]]; then
            continue
        elif [[ $REPLY =~ \+\+\+\ (b/)?([^[:blank:]$esc]+).* ]]; then
            path=${BASH_REMATCH[2]}
        elif [[ $REPLY =~ @@\ -[0-9]+(,[0-9]+)?\ \+([0-9]+)(,[0-9]+)?\ @@.* ]]; then
            line=${BASH_REMATCH[2]}
        elif [[ $REPLY =~ ^($esc\[[0-9;]+m)*([\ +-]) ]]; then
            echo "$path:$line:$REPLY"
            if [[ ${BASH_REMATCH[2]} != - ]]; then
                ((line++))
            fi
        fi
    done
}

It can produce output such as:

$ git diff | diff-lines
http-fetch.c:1: #include "cache.h"
http-fetch.c:2: #include "walker.h"
http-fetch.c:3: 
http-fetch.c:4:-int cmd_http_fetch(int argc, const char **argv, const char *prefix)
http-fetch.c:4:+int main(int argc, const char **argv)
http-fetch.c:5: {
http-fetch.c:6:+       const char *prefix;
http-fetch.c:7:        struct walker *walker;
http-fetch.c:8:        int commits_on_stdin = 0;
http-fetch.c:9:        int commits;
http-fetch.c:19:        int get_verbosely = 0;
http-fetch.c:20:        int get_recover = 0;
http-fetch.c:21: 
http-fetch.c:22:+       prefix = setup_git_directory();
http-fetch.c:23:+
http-fetch.c:24:        git_config(git_default_config, NULL);
http-fetch.c:25: 
http-fetch.c:26:        while (arg < argc && argv[arg][0] == '-') {
fetch.h:1: #include "config.h"
fetch.h:2: #include "http.h"
fetch.h:3: 
fetch.h:4:-int cmd_http_fetch(int argc, const char **argv, const char *prefix);
fetch.h:4:+int main(int argc, const char **argv);
fetch.h:5: 
fetch.h:6: void start_fetch(const char* uri);
fetch.h:7: bool fetch_succeeded(int status_code);

from a diff like this:

$ git diff
diff --git a/builtin-http-fetch.c b/http-fetch.c
similarity index 95%
rename from builtin-http-fetch.c
rename to http-fetch.c
index f3e63d7..e8f44ba 100644
--- a/builtin-http-fetch.c
+++ b/http-fetch.c
@@ -1,8 +1,9 @@
 #include "cache.h"
 #include "walker.h"

-int cmd_http_fetch(int argc, const char **argv, const char *prefix)
+int main(int argc, const char **argv)
 {
+       const char *prefix;
        struct walker *walker;
        int commits_on_stdin = 0;
        int commits;
@@ -18,6 +19,8 @@ int cmd_http_fetch(int argc, const char **argv, const char *prefix)
        int get_verbosely = 0;
        int get_recover = 0;

+       prefix = setup_git_directory();
+
        git_config(git_default_config, NULL);

        while (arg < argc && argv[arg][0] == '-') {
diff --git a/fetch.h b/fetch.h
index 5fd3e65..d43e0ca 100644
--- a/fetch.h
+++ b/fetch.h
@@ -1,7 +1,7 @@
 #include "config.h"
 #include "http.h"

-int cmd_http_fetch(int argc, const char **argv, const char *prefix);
+int main(int argc, const char **argv);

 void start_fetch(const char* uri);
 bool fetch_succeeded(int status_code);

If you only want to show added/removed/modified lines, and not the surrounding context, you can pass -U0 to git diff:

$ git diff -U0 | diff-lines
http-fetch.c:4:-int cmd_http_fetch(int argc, const char **argv, const char *prefix)
http-fetch.c:4:+int main(int argc, const char **argv)
http-fetch.c:6:+       const char *prefix;
http-fetch.c:22:+       prefix = setup_git_directory();
http-fetch.c:23:+
fetch.h:4:-int cmd_http_fetch(int argc, const char **argv, const char *prefix);
fetch.h:4:+int main(int argc, const char **argv);

It's robust against ANSI color codes, so you can pass --color=always to git diff to get the usual color coding for added/removed lines.

The output can be easily grepped:

$ git diff -U0 | diff-lines | grep 'main'
http-fetch.c:4:+int main(int argc, const char **argv)
fetch.h:4:+int main(int argc, const char **argv);

In your case git diff -U0 would give:

$ git diff -U0 | diff-lines
test.txt:2:+new line here
test.txt:3:+another new line
test.txt:6:-will be removed
test.txt:6:-git repo
test.txt:6:+git

If you just want the line numbers, change the echo "$path:$line:$REPLY" to just echo "$line" and pipe the output through uniq.

Answer 6

git diff --stat will show you the output you get when committing stuff which is the one you are referring to I guess.

git diff --stat

For showing exactly the line numbers that has been changed you can use

git blame -p <file> | grep "Not Committed Yet"

And the line changed will be the last number before the ending parenthesis in the result. Not a clean solution though :(