The git checkout-index command is a lesser-known but occasionally useful Git command. It allows you to check files out of the index (the staging area) and into the working directory.

Basic Syntax

git checkout-index [options] [--] <paths>

Common Options:

• -a: Checkout all files.

• -f: When checking out files from the index, overwrite existing files in the working directory (without this option, Git won't overwrite changed files in your working directory).

• -q: Quiet mode, suppress feedback messages.

• -u: Update the timestamp of the checked-out files.

• --temp: Instead of checking out files, write the content of the requested paths to a temporary file and print its name to standard output.

Workshop Exercises

1. Basic Usage

   • Task: Set up a Git repository, create a file, stage the file, then remove it from the working directory. Use git checkout-index to recover the file from the index.

   • Steps:

     1. mkdir checkout-index-demo && cd checkout-index-demo

     2. git init

     3. echo "Hello Git" > hello.txt

     4. git add hello.txt

     5. rm hello.txt

        

     6. Verify the file is gone with ls

     7. git checkout-index hello.txt

   • Solution: After step 7, you should see hello.txt in the directory again with its content as "Hello Git".

     

2. Force Checkout

   • Task: Modify a staged file in the working directory and attempt to check it out from the index. This should fail without the -f option.

   • Steps:

     1. echo "Change in file" >> hello.txt

     2. Try recovering the staged version with git checkout-index hello.txt. It will fail.

        

     3. Now try: git checkout-index -f hello.txt

   • Solution: After step 3, hello.txt should be reverted to its content from step 1 of the previous exercise, i.e., "Hello Git".

3. Checkout All Files

   • Task: Add multiple files to the staging area, modify them, then recover them all using a single command.

   • Steps:

     1. echo "File 2" > file2.txt

     2. echo "File 3" > file3.txt

     3. git add file2.txt file3.txt

     4. echo "Modified" >> hello.txt

     5. echo "Modified" >> file2.txt

        

     6. git checkout-index -a -f

   • Solution: After step 6, all files in the directory should be reverted to their staged versions.

4. Temporary Checkout

   • Task: Create a temporary copy of a staged file using git checkout-index.

   • Steps:

     1. git checkout-index --temp hello.txt

        

   • Solution: After step 1, the terminal should display a path to a temporary file. If you view the content of this temporary file, it will match the staged version of hello.txt.

These exercises should give you a good understanding of git checkout-index and its utility in specific scenarios.

References

1. git-checkout-index