Check whether the destination file/folder already exists

[davidebeatrici]

$ mkdir /tmp/ipfs-test && cd /tmp/ipfs-test
$ mkdir folder
$ echo "Hello" > folder/test.txt
$ touch out.car
$ car create --output out.car folder
$ ls -l
total 4
drwxrwxr-x 2 user user  40 Jan 25 22:10 folder
-rw-rw-r-- 1 user user 352 Jan 25 22:11 out.car

[davidebeatrici]

After further testing, I can see why it's the way it is: content can be appended to an existing CAR file.

In my example I created an empty file and car happily overwrote it. However, if the file contains random data this is the output:

$ echo "Hello" > "test.car"
$ car create --version=1 --output test.car test.txt
2026/01/26 21:39:12 unexpected EOF
$ cat test.car
Hello

In my opinion there should be a parameter such as --append to enable the behavior.

Or even better: a new option/mode to be used in place of create. Something like append, add or concat.

[rvagg]

yeah, bad footgun and I think the best way to handle this is your --append suggestion as opt-in, with an error if the file exists otherwise