bash script that squashes commits with same name in a row

Question

I want to create bash script that squashes commits with same name in a row. The user should be able to enter the commit number between which it will search for commit names and if it finds 2 similar names in a row it should merge the commits.

Following is the code for getting the range of commits but i want to know how to merge commits having same name in a row.

#!/bin/bash

echo 'Enter starting commit number 1 or 2'
read start
echo 'Enter ending commit number 3,4 or 5'
read end

rebaser=`git rebase -i HEAD~$end HEAD~$start`

"and if it finds 2 similar names in a row" – how similar is similar? — knittl, Oct 20 '22 at 12:14
Note that `HEAD~$start` will leave you in detached HEAD state. You usually want to rebase a branch, not a commit. — knittl, Oct 20 '22 at 13:26

knittl · Answer 1 · 2022-10-20T13:38:03.897

You can run rebase with a custom sequence editor. awk makes it simple enough (depending on your definition of "simple") to detect identical commit messages:

GIT_SEQUENCE_EDITOR='awk "!/^#/{action=\$1;commit=\$2;\$1=\$2=\"\";if(msg==\$0){action=\"fixup\"};print action,commit,\$0;msg=\$0;next}{print}" "$1" > "$1.tmp"; mv "$1.tmp" "$1";:' git rebase -i upstream

The editor command will receive the todo list and can modify it by overwriting the file passed in as $1.

It's probably best to store this sequencer command in a separate executable script and then simply do GIT_SEQUENCE_EDITOR=path/to/yourscript.sh or to define a Git alias. This would avoid the escaping madness happening above due to different contexts.

The formatted (and unescaped) awk script with explanations:

!/^#/{ # only process non-comment lines
  action=$1; # first field is the action (pick, fixup, etc.)
  commit=$2; # second field is the commit id
  $1=$2="";  # ignore first two fields when comparing message
  if(msg == $0) {
    action="fixup" # message was identical to previous line, squash commit
  };
  print action,commit,$0; # print action, commit id and message (actually, only action + id are required)
  msg=$0; # remember current message for next line
  next    # start processing next line
}
{print} # print comment lines

bash script that squashes commits with same name in a row

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