#16854 experimental_shell_command outputs do not preserve symlinks Issue created by huonw Describe the bug Any symlinks in the

outputs

list of

experimental_shell_command

are resolved to normal files, duplicating the contents of the thing they link to. It'd be nifty to have the option to preserve them. At the very least, it'd be good to document this behaviour. There's some cases where being a symlink (rather than a normal file) is be semantically relevant. For instance, with node, it seems the files within

node_modules/.bin

are symlinks into the rest of

node_modules

, and turning a link into a normal file causes those executable scripts to stop working. Consider the following `BUILD`:

experimental_shell_command(
    name="make-link",
    command="""
    echo normal > normal.txt
    ln -s normal.txt link.txt
    # double check
    test -L link.txt
    """,
    tools=["ln"],
    outputs=["*.txt"]
)

experimental_run_shell_command(
    name="check-link",
    command="""
    cd {chroot}
    ls -l
    test -L link.txt || echo "not a link!!"
    """,
    dependencies=[":make-link"]
)

The key is

make-link

, while

check-link

is just a way to be able to introspect what

make-link

splats out when used as a dependency. The output of

./pants run //:check-link

is:

total 16
-rw-r--r--  1 huon  staff  7 14 Sep 12:02 link.txt
-rw-r--r--  1 huon  staff  7 14 Sep 12:02 normal.txt
not a link!!

But I'd expect it to not have the

not a link!!

printed, and the

ls

line for

link.txt

should be

lrwxr-xr-x ... link.txt -> normal.txt

. Full reproducer https://gist.github.com/huonw/4ebc739a7a04cdd9bcf137bdcbc2018f:

git clone <mailto:git@gist.github.com|git@gist.github.com>:4ebc739a7a04cdd9bcf137bdcbc2018f.git
cd 4ebc739a7a04cdd9bcf137bdcbc2018f
./pants run //:check-link

Pants version 2.13.0 2.14.0rc0 OS macOS Additional info Thanks for pants! 👖 pantsbuild/pants

#16854 experimental_shell_command outputs do not preserve symlinks Issue closed as completed by thejcannon pantsbuild/pants