opam 2.0.9 release

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We are pleased to announce the minor release of opam 2.0.9.

This new version contains some back-ported fixes.

New features

• Back-ported ability to load upgraded roots read-only; allows applications compiled with opam-state 2.0.9 to load a root which has been upgraded to opam 2.1 [#4636]
• macOS sandbox now supports OPAM_USER_PATH_RO for adding a custom read-only directory to the sandbox [#4589, #4609]
• OPAMROOT and OPAMSWITCH now reflect the --root and --switch parameters in the package build [#4668]
• When built with opam-file-format 2.1.3+, opam-format 2.0.x displays better errors for newer opam files [#4394]

Bug fixes

• Linux sandbox now mounts host $TMPDIR read-only, then sets the sandbox $TMPDIR to a new separate tmpfs. Hardcoded /tmp access no longer works if TMPDIR points to another directory [#4589]
• Stop clobbering DUNE_CACHE in the sandbox script [#4535, fixing ocaml/dune#4166]
• Ctrl-C now correctly terminates builds with bubblewrap; sandbox now requires bubblewrap 0.1.8 or later [#4400]
• Linux sandbox script no longer makes PWD read-write on remove actions [#4589]
• Lint W59 and E60 no longer trigger for packages flagged conf [#4549]
• Reduce the length of temporary file names for pin caching to ease pressure on Windows [#4590]
• Security: correct quoting of arguments when removing switches [#4707]
• Stop advertising the removed option --compiler when creating local switches [#4718]
• Pinning no longer fails if the archive's opam file is malformed [#4580]
• Fish: stop using deprecated ^ syntax to fix support for Fish 3.3.0+ [#4736]

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Installation instructions (unchanged):

1. From binaries: run

bash -c "sh <(curl -fsSL https://raw.githubusercontent.com/ocaml/opam/master/shell/install.sh) --version 2.0.9"

or download manually from the Github "Releases" page to your PATH. In this case, don't forget to run opam init --reinit -ni to enable sandboxing if you had version 2.0.0~rc manually installed or to update you sandbox script.

2. From source, using opam:

opam update; opam install opam-devel

(then copy the opam binary to your PATH as explained, and don't forget to run opam init --reinit -ni to enable sandboxing if you had version 2.0.0~rc manually installed or to update your sandbox script)

3. From source, manually: see the instructions in the README.

We hope you enjoy this new minor version, and remain open to bug reports and suggestions.

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