feat(cp): support custom commit message templates

bin/git-cp

@@ -4,17 +4,32 @@ set -euo pipefail
 PROGRAM=$0
 CURRENT_FILENAME=""
 DESTINATION_FILENAME=""
+COMMIT_TEMPLATE="{}"
+
+function commit_message()
+{
+    # Replace every {} in the template with the default commit message
+    printf '%s\n' "${COMMIT_TEMPLATE//\{\}/"$1"}"
+}
 
 function usage()
 {
-    echo 1>&2 "USAGE: ${PROGRAM} CURRENT_FILENAME DESTINATION_FILENAME"
+    echo 1>&2 "USAGE: ${PROGRAM} [--commit-template TEMPLATE] CURRENT_FILENAME DESTINATION_FILENAME"
 }
 
 while [[ $# -gt 0 ]]
 do
   key="$1"
 
-  if [[ "$CURRENT_FILENAME" == "" ]]; then
+  if [[ "$key" == "--commit-template" ]]; then
+      if [[ $# -lt 2 ]]; then
+          usage
+          exit 30
+      fi
+      COMMIT_TEMPLATE=$2
+      shift 2
+      continue
+  elif [[ "$CURRENT_FILENAME" == "" ]]; then
       CURRENT_FILENAME=$key
   elif [[ "$DESTINATION_FILENAME" == "" ]]; then
       DESTINATION_FILENAME=$key
@@ -62,15 +77,15 @@ else
 
     # Move the original file to the new destination, in this branch
     git mv "${CURRENT_FILENAME}" "${DESTINATION_FILENAME}"
-    git commit -nm "--Duplicate $CURRENT_FILENAME history into $DESTINATION_FILENAME"
+    git commit -nm "$(commit_message "--Duplicate $CURRENT_FILENAME history into $DESTINATION_FILENAME")"
 
     # Restore the original file to keep it in the history
     git checkout HEAD~ "${CURRENT_FILENAME}"
-    git commit -nm "--Restore $CURRENT_FILENAME"
+    git commit -nm "$(commit_message "--Restore $CURRENT_FILENAME")"
 
     # Switch to the original branch and merge this back in.
     git checkout -
-    git merge --no-ff "$BRANCH_NAME" -m "Copy $CURRENT_FILENAME into $DESTINATION_FILENAME"
+    git merge --no-ff "$BRANCH_NAME" -m "$(commit_message "Copy $CURRENT_FILENAME into $DESTINATION_FILENAME")"
 
     # We're now done with the branch, so delete it.
     # We shouldn't need -D here, as we've already merged it back in.

man/git-cp.1

@@ -1,19 +1,35 @@
 .\" generated with Ronn-NG/v0.9.0
 .\" http://github.com/apjanke/ronn-ng/tree/0.9.0
-.TH "GIT\-CP" "1" "March 2020" "" "Git Extras"
+.TH "GIT\-CP" "1" "October 2026" "" "Git Extras"
 .SH "NAME"
 \fBgit\-cp\fR \- Copy a file keeping its history
 .SH "SYNOPSIS"
-\fBgit\-cp\fR <current_filename> <destination_filename>
+\fBgit\-cp\fR [\-\-commit\-template <template>] <current_filename> <destination_filename>
 .SH "DESCRIPTION"
 Copy a file keeping its git history\. This allows merge conflict handling\.
+.P
+Use \fB\-\-commit\-template\fR to customize each of the three commits created by the copy\. Every \fB{}\fR in the template is replaced with the default commit message, so text can be added before or after it\. The default template is \fB{}\fR, which leaves commit messages unchanged\.
 .SH "EXAMPLES"
 Copy README into README\.txt
 .IP "" 4
 .nf
 $ git cp README README\.txt
 .fi
 .IP "" 0
+.P
+Associate the copy commits with issue #1252
+.IP "" 4
+.nf
+$ git cp \-\-commit\-template \'#1252 {}\' README README\.txt
+.fi
+.IP "" 0
+.P
+Append a trailer to the copy commits
+.IP "" 4
+.nf
+$ git cp \-\-commit\-template \'{} [skip ci]\' README README\.txt
+.fi
+.IP "" 0
 .SH "AUTHOR"
 Written by Rémy Hubscher <\fI\%mailto:hubscher\.remy@gmail\.com\fR>
 .SH "REPORTING BUGS"

man/git-cp.md

@@ -3,18 +3,28 @@ git-cp(1) -- Copy a file keeping its history
 
 ## SYNOPSIS
 
-`git-cp` <current_filename> <destination_filename>
+`git-cp` [--commit-template <template>] <current_filename> <destination_filename>
 
 ## DESCRIPTION
 
 Copy a file keeping its git history. This allows merge conflict handling.
 
+Use `--commit-template` to customize each of the three commits created by the copy. Every `{}` in the template is replaced with the default commit message, so text can be added before or after it. The default template is `{}`, which leaves commit messages unchanged.
+
 ## EXAMPLES
 
   Copy README into README.txt
 
     $ git cp README README.txt
 
+  Associate the copy commits with issue #1252
+
+    $ git cp --commit-template '#1252 {}' README README.txt
+
+  Append a trailer to the copy commits
+
+    $ git cp --commit-template '{} [skip ci]' README README.txt
+
 ## AUTHOR
 
 Written by Rémy Hubscher &lt;<hubscher.remy@gmail.com>&gt;

tests/git-cp.bats

@@ -0,0 +1,55 @@
+# shellcheck shell=bash
+
+source "$BATS_TEST_DIRNAME/test_util.sh"
+
+setup_file() {
+	test_util.setup_file
+	test_util.install_command cp
+}
+
+setup() {
+	test_util.cd_test
+	test_util.git_init
+	printf 'original\n' > original.txt
+	git add original.txt
+	git commit -m 'initial'
+}
+
+@test "applies the commit template prefix to all three copy commits" {
+	run git cp --commit-template '#1252 {}' original.txt duplicate.txt
+	assert_success
+	run git log --format=%s
+	assert_success
+	assert_line '#1252 Copy original.txt into duplicate.txt'
+	assert_line '#1252 --Restore original.txt'
+	assert_line '#1252 --Duplicate original.txt history into duplicate.txt'
+	[ -f original.txt ]
+	[ -f duplicate.txt ]
+}
+
+@test "rejects a missing template without changing the repository" {
+	run git cp original.txt duplicate.txt --commit-template
+	assert_failure 30
+	[ ! -e duplicate.txt ]
+	[ "$(git rev-list --count HEAD)" -eq 1 ]
+}
+
+@test "applies the commit template suffix to all three copy commits" {
+	run git cp --commit-template '{} [skip ci]' original.txt duplicate.txt
+	assert_success
+	run git log --format=%s
+	assert_success
+	assert_line 'Copy original.txt into duplicate.txt [skip ci]'
+	assert_line '--Restore original.txt [skip ci]'
+	assert_line '--Duplicate original.txt history into duplicate.txt [skip ci]'
+}
+
+@test "keeps existing commit messages without the option" {
+	run git cp original.txt duplicate.txt
+	assert_success
+	run git log --format=%s
+	assert_success
+	assert_line 'Copy original.txt into duplicate.txt'
+	assert_line '--Restore original.txt'
+	assert_line '--Duplicate original.txt history into duplicate.txt'
+}