How to generate a git patch for a specific commit

Question

I need to write a script that creates patches for a list of SHA1 commit numbers   I tried using git format-patch  lt the SHA1 gt   but that generated a patch for each commit since that SHA1  After a few hundred patches were generated  I had to kill the process   Is there a way to generate a patch only for the specific SHA1

User · Answer

With my mercurial background I was going to use   git log --patch -1  ID  gt   file   But I am considering using git format-patch -1  ID now

User · Answer

What is the way to generate a patch only for the specific SHA1   It s quite simple   Option 1  git show commitID  gt  myFile patch  Option 2  git commitID 1  commitID  gt  myFile patch  Note  Replace commitID with actual commit id  SHA1 commit code

User · Answer

For generating the patches from the topmost  commits from a specific sha1 hash   git format-patch - lt n gt   lt SHA1 gt    The last 10 patches from head in a single patch file   git format-patch -10 HEAD --stdout  gt  0001-last-10-commits patch

User · Answer

if you just want diff the specified file  you can       git diff master  766eceb --  connections     000-mysql-connector patch

User · Answer

To generate path from a specific commit  not the last commit    git format-patch -M -C COMMIT VALUE 1  COMMIT VALUE

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Say you have commit id 2 after commit 1 you would be able to run   git diff 2 1  gt  mypatch diff   where 2 and 1 are SHA hashes

User · Answer

If you want to be sure the  single commit  patch will be applied on top of a specific commit  you can use the new git 2 9  June 2016  option git format-patch --base git format-patch --base COMMIT VALUE  -M -C COMMIT VALUE   COMMIT VALUE    or git format-patch --base auto -M -C COMMIT VALUE   COMMIT VALUE    or git config format useAutoBase true git format-patch -M -C COMMIT VALUE   COMMIT VALUE  See commit bb52995  commit 3de6651  commit fa2ab86  commit ded2c09  26 Apr 2016  by Xiaolong Ye        Merged by Junio C Hamano -- gitster -- in commit 72ce3ff  23 May 2016   format-patch  add  --base  option to record base tree info   Maintainers or third party testers may want to know the exact base tree the patch series applies to  Teach git format-patch a  --base  option to record the base tree info and append it at the end of the first message  either the cover letter or the first patch in the series   The base tree info consists of the  quot base commit quot   which is a well-known commit that is part of the stable part of the project history everybody else works off of  and zero or more  quot prerequisite patches quot   which are well-known patches in flight that is not yet part of the  quot base commit quot  that need to be applied on top of  quot base commit quot  in topological order before the patches can be applied  The  quot base commit quot  is shown as  quot base-commit   quot  followed by the 40-hex of the commit object name  A  quot prerequisite patch quot  is shown as  quot prerequisite-patch-id   quot  followed by the 40-hex  quot patch id quot   which can be obtained by passing the patch through the  quot git patch-id --stable quot  command    Git 2 23  Q3 2019  will improve that  because the  quot --base quot  option of  quot format-patch quot  computed the patch-ids for prerequisite patches in an unstable way  which has been updated to compute in a way that is compatible with  quot git patch-id --stable quot   See commit a8f6855  commit 6f93d26  26 Apr 2019  by Stephen Boyd  akshayka    Merged by Junio C Hamano -- gitster -- in commit 8202d12  13 Jun 2019   format-patch  make --base patch-id output stable   We weren t flushing the context each time we processed a hunk in the patch-id generation code in diff c  but we were doing that when we generated  quot stable quot  patch-ids with the  patch-id  tool  Let s port that similar logic over from patch-id c into diff c so we can get the same hash when we re generating patch-ids for  format-patch --base   types of command invocations    Before Git 2 24  Q4 2019    quot git format-patch -o  lt outdir gt  quot  did an equivalent of  quot mkdir  lt outdir gt  quot  not  quot mkdir -p  lt outdir gt  quot   which is being corrected  See commit edefc31  11 Oct 2019  by Bert Wesarg  bertwesarg    Merged by Junio C Hamano -- gitster -- in commit f1afbb0  18 Oct 2019   format-patch  create leading components of output directory Signed-off-by  Bert Wesarg    git format-patch -o   did an equivalent of  mkdir  lt outdir gt   not  mkdir -p  lt outdir gt    which is being corrected    Avoid the usage of  adjust shared perm  on the leading directories which may have security implications  Achieved by temporarily disabling of  config sharedRepository  like  git init  does    With Git 2 25  Q1 2020    quot git rebase quot  did not work well when format useAutoBase configuration variable is set  which has been corrected  See commit cae0bc0  commit 945dc55  commit 700e006  commit a749d01  commit 0c47e06  04 Dec 2019  by Denton Liu  Denton-L    Merged by Junio C Hamano -- gitster -- in commit 71a7de7  16 Dec 2019   rebase  fix format useAutoBase breakage Reported-by  Christian Biesinger Signed-off-by  Denton Liu With format useAutoBase   true  running rebase resulted in an error  fatal  failed to get upstream  if you want to record base commit automatically  please use git branch --set-upstream-to to track a remote branch  Or you could specify base commit by --base  lt base-commit-id gt  manually error  git encountered an error while preparing the patches to replay these revisions   ede2467cdedc63784887b587a61c36b7850ebfac  d8f581194799ae29bf5fa72a98cbae98a1198b12  As a result  git cannot rebase them   Fix this by always passing --no-base to format-patch from rebase so that the effect of format useAutoBase is negated    With Git 2 29  Q4 2020    quot git format-patch quot  man  learns to take  quot whenAble quot  as a possible value for the format useAutoBase configuration variable to become no-op when the automatically computed base does not make sense  See commit 7efba5f  01 Oct 2020  by Jacob Keller  jacob-keller    Merged by Junio C Hamano -- gitster -- in commit 5f8c70a  05 Oct 2020   format-patch  teach format useAutoBase  quot whenAble quot  option Signed-off-by  Jacob Keller   The format useAutoBase configuration option exists to allow users to enable  --base auto  for format-patch by default  This can sometimes lead to poor workflow  due to unexpected failures when attempting to format an ancient patch    git format-patch -1  lt an old commit gt  fatal  base commit shouldn t be in revision list    This can be very confusing  as it is not necessarily immediately obvious that the user requested a --base  since this was in the configuration  not on the command line   We do want --base auto to fail when it cannot provide a suitable base  as it would be equally confusing if a formatted patch did not include the base information when it was requested  Teach format useAutoBase a new mode   quot whenAble quot   This mode will cause format-patch to attempt to include a base commit when it can  However  if no valid base commit can be found  then format-patch will continue formatting the patch without a base commit  In order to avoid making yet another branch name unusable with --base  do not teach --base whenAble or --base whenable  Instead  refactor the base commit option to use a callback  and rely on the global configuration variable auto base  This does mean that a user cannot request this optional base commit generation from the command line  However  this is likely not too valuable  If the user requests base information manually  they will be immediately informed of the failure to acquire a suitable base commit  This allows the user to make an informed choice about whether to continue the format  Add tests to cover the new mode of operation for --base   git config now includes in its man page   format-patch by default  Can also be set to  quot whenAble quot  to allow enabling --base auto if a suitable base is available  but to skip adding base info otherwise without the format dying    With Git 2 30  Q1 2021    quot git format-patch --output there quot  man  did not work as expected and instead crashed   The option is now supported   See commit dc1672d  commit 1e1693b  commit 4c6f781  04 Nov 2020  by Jeff King  peff    Merged by Junio C Hamano -- gitster -- in commit 5edc8bd  18 Nov 2020   format-patch  support --output option Reported-by  Johannes Postler Signed-off-by  Jeff King   We ve never intended to support diff s --output option in format-patch  And until baa4adc66a  parse-options  disable option abbreviation with PARSE OPT KEEP UNKNOWN  2019-01-27  Git v2 22 0-rc0   it was impossible to trigger  We first parse the format-patch options before handing the remainder off to setup revisions    Before that commit  we d accept  quot --output foo quot  as an abbreviation for  quot --output-directory foo quot   But afterwards  we don t check abbreviations  and --output gets passed to the diff code  This results in nonsense behavior and bugs  The diff code will have opened a filehandle at rev diffopt file  but we ll overwrite that with our own handles that we open for each individual patch file  So the --output file will always just be empty  But worse  the diff code also sets rev diffopt close file  so log tree commit   will close the filehandle itself  And then the main loop in cmd format patch   will try to close it again  resulting in a double-free  The simplest solution would be to just disallow --output with format-patch  as nobody ever intended it to work  However  we have accidentally documented it  because format-patch includes diff-options   And it does work with  quot git log quot  man    which writes the whole output to the specified file  It s easy enough to make that work for format-patch  too  it s really the same as --stdout  but pointed at a specific file  We can detect the use of the --output option by the  quot close file quot  flag  note that we can t use rev diffopt file  since the diff setup will otherwise set it to stdout   So we just need to unset that flag  but don t have to do anything else  Our situation is otherwise exactly like --stdout  note that we don t fclose   the file  but nor does the stdout case  exiting the program takes care of that for us

User · Answer

This command  as suggested already by  Naftuli Tzvi Kay    git format-patch -1 HEAD   Replace HEAD with specific hash or range   will generate the patch file for the latest commit formatted to resemble UNIX mailbox format      - lt n gt  - Prepare patches from the topmost  commits    Then you can re-apply the patch file in a mailbox format by   git am -3k 001  patch   See  man git-format-patch

User · Answer

Try   git format-patch -1  lt sha gt    or  git format-patch -1 HEAD   According to the documentation link above  the -1 flag tells git how many commits should be included in the patch      - lt n        nbsp  nbsp  nbsp  nbsp    Prepare patches from the topmost  commits      Apply the patch with the command   git am  lt  file patch

User · Answer

git format-patch commit Id 1  commit Id   git apply patch-file-name   Fast and simple solution

[git] How to generate a git patch for a specific commit?

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