git diff file against its last change

Question

Is it possible to get git to produce a diff between a specific file as it exists now  and as it existed before the last commit that changed it   That is  if we know     git log --oneline myfile 123abc Fix some stuff 456def Frobble the foos 789dba Initial commit   Then git diff 456def myfile shows the last change to myfile  Is is possible to do the same without the knowledge produced by the git log  what changed in 123abc

User · Answer

One of the ways to use git diff is   git diff  lt commit gt   lt path gt    And a common way to refer one commit of the last commit is as a relative path to the actual HEAD  You can reference previous commits as HEAD   in your example this will be 123abc  or HEAD    456def in your example   etc      So the answer to your question is   git diff HEAD   myfile

User · Answer

This does exist  but it s actually a feature of git log   git log -p  --follow   -1   lt path gt    Note that -p can also be used to show the inline diff from a single commit   git log -p -1  lt commit gt    Options used    -p  also -u or --patch  is hidden deeeeeeeep in the git-log man page  and is actually a display option for git-diff  When used with log  it shows the patch that would be generated for each commit  along with the commit information mdash and hides commits that do not touch the specified  lt path gt    This behavior is described in the paragraph on --full-diff  which causes the full diff of each commit to be shown   -1 shows just the most recent change to the specified file  -n 1 can be used instead of -1   otherwise  all non-zero diffs of that file are shown  --follow is required to see changes that occurred prior to a rename    As far as I can tell  this is the only way to immediately see the last set of changes made to a file without using git log  or similar  to either count the number of intervening revisions or determine the hash of the commit   To see older revisions changes  just scroll through the log  or specify a commit or tag from which to start the log   Of course  specifying a commit or tag returns you to the original problem of figuring out what the correct commit or tag is    Credit where credit is due    I discovered log -p thanks to this answer  Credit to FranciscoPuga and this answer for showing me the --follow option  Credit to ChrisBetti for mentioning the -n 1 option and atatko for mentioning the -1 variant  Credit to sweaver2112 for getting me to actually read the documentation and figure out what -p  means  semantically

User · Answer

If you are fine using a graphical tool this works very well   gitk  lt file gt    gitk now shows all commits where the file has been updated  Marking a commit will show you the diff against the previous commit in the list  This also works for directories  but then you also get to select the file to diff for the selected commit  Super useful

[git] git diff file against its last change

Examples related to git

Examples related to git-diff