diff options
| -rw-r--r-- | doc/manual/src/command-ref/nix-shell.md | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/doc/manual/src/command-ref/nix-shell.md b/doc/manual/src/command-ref/nix-shell.md index 8bcad85e1..0bd54b955 100644 --- a/doc/manual/src/command-ref/nix-shell.md +++ b/doc/manual/src/command-ref/nix-shell.md @@ -110,18 +110,18 @@ shell in which to build it: ```console $ nix-shell '<nixpkgs>' -A pan -[nix-shell]$ unpackPhase +[nix-shell]$ eval ${unpackPhase:-unpackPhase} [nix-shell]$ cd pan-* -[nix-shell]$ configurePhase -[nix-shell]$ buildPhase +[nix-shell]$ eval ${configurePhase:-configurePhase} +[nix-shell]$ eval ${buildPhase:-buildPhase} [nix-shell]$ ./pan/gui/pan ``` -Note: Other packages may override these phases (the unpackPhase, -configurePhase, buildPhase, etc). -For those, it may be required to do something like -`eval "$configurePhase-configurePhase"` or `eval "$configurePhase"` -depending on how that package's nix files have been written. +The reason we use form `eval ${configurePhase:-configurePhase}` here is because +those packages that override these phases do so by exporting the overridden +values in the environment variable of the same name. +Here bash is being told to either evaluate the contents of 'configurePhase', +if it exists as a variable, otherwise evaluate the configurePhase function. To clear the environment first, and do some additional automatic initialisation of the interactive shell: |