`env_append`

env_append returns a dependency that adds one item to the end of an environment variable. Items are joined with the host path-list separator, making the function suitable for PATH and similar variables.

Arguments

Argument	Required	Description
`key`	Yes	Environment variable name to change.
`value`	Yes	String item to append.
`unique`	No	Keep the existing value when an equivalent item is already present. Defaults to `False`.

Uniqueness uses exact string comparison on Linux and macOS. On Windows, PATH entries are compared case-insensitively; other variables use exact comparison.

Examples

Append one search path

load("@os@1", "env_append", "run")

run(
    ("project-linter", "check"),
    deps=[env_append("PATH", "tools/bin")],
)

Avoid duplicate entries

load("@os@1", "env_append", "run")

tool_paths = (
    env_append("PATH", "tools/bin", unique=True) +
    env_append("PATH", "vendor/bin", unique=True)
)

run(("project-linter", "check"), deps=[tool_paths])