Environment (env)

This object is returned by environment() and stores detailed information about how environment variables should be set. It should be passed as the env keyword argument to tests and other functions.

Since 0.58.0 env.append() and env.prepend() can be called multiple times on the same varname. Earlier Meson versions would warn and only the last operation took effect.

Since 1.5.0 This object becomes immutable after first use. This means that calling append(), prepend() or set() will cause a deprecation warning if this object has already been used in any function arguments. However, assignment creates a mutable copy.

Returned by

Environment objects are returned by the following functions and methods:

• environment()

Example

```meson
env = environment()

# MY_PATH will be '0:1:2:3'
env.set('MY_PATH', '1')
env.append('MY_PATH', '2')
env.append('MY_PATH', '3')
env.prepend('MY_PATH', '0')

# Deprecated since 1.5.0
run_command('script.py', env: env)
env.append('MY_PATH', '4')

# Allowed and only env2 is modified
env2 = env
env2.append('MY_PATH', '4')
```

Environment methods

env.append()

appends the given values to the old value of the environment variable, e.g. env.append('FOO', 'BAR', 'BAZ', separator : ';') produces BOB;BAR;BAZ if FOO had the value BOB and plain BAR;BAZ if the value was not defined.

# appends the given values to
void append(
  str variable,     # The variable to modify
  str Value...,     # The values to append

  # Keyword arguments:
  separator : str  # The separator to use
)

Arguments

The method env.append() accepts the following positional arguments:

Name	Type	Description	Tags
variable	str	The variable to modify

Additionally, the method accepts between 0 and infinity variadic arguments (Value...) of type str.

The values to append

Finally, env.append() accepts the following keyword arguments:

Name	Type	Description	Tags
separator	str	The separator to use. If not explicitly specified, the default path separator for the host operating system will be used, i.e. ';' for Windows and ':' for UNIX/POSIX systems.

---

env.prepend()

Same as append except that it writes to the beginning of the variable.

# Same as `append` except that it writes to the beginning of the variable
void prepend(
  str variable,     # The variable to modify
  str Value...,     # The values to prepend

  # Keyword arguments:
  separator : str  # The separator to use
)

Arguments

The method env.prepend() accepts the following positional arguments:

Name	Type	Description	Tags
variable	str	The variable to modify

Additionally, the method accepts between 0 and infinity variadic arguments (Value...) of type str.

The values to prepend

Finally, env.prepend() accepts the following keyword arguments:

Name	Type	Description	Tags
separator	str	The separator to use. If not explicitly specified, the default path separator for the host operating system will be used, i.e. ';' for Windows and ':' for UNIX/POSIX systems.

---

env.set()

Sets the environment variable specified in the first argument to the values in the varargs joined by the separator. For instance, env.set('FOO', 'BAR'), sets envvar FOO to value BAR.

# Sets the environment variable
void set(
  str variable,     # The variable to modify
  str Value...,     # The values to set

  # Keyword arguments:
  separator : str  # The separator to use
)

Arguments

The method env.set() accepts the following positional arguments:

Name	Type	Description	Tags
variable	str	The variable to modify

Additionally, the method accepts between 0 and infinity variadic arguments (Value...) of type str.

The values to set

Finally, env.set() accepts the following keyword arguments:

Name	Type	Description	Tags
separator	str	The separator to use. If not explicitly specified, the default path separator for the host operating system will be used, i.e. ';' for Windows and ':' for UNIX/POSIX systems.

---

env.unset()

Unset the specified environment variable. If this variable does not exist, nothing happens.

void unset()

---