getenv — Read environment variables in MATLAB and RunMat.

getenv(name) returns the value of environment variable name visible to the current process. Calling getenv with no arguments returns a struct of available variables, consistent with MATLAB semantics.

Syntax

env = getenv()
value = getenv(NAME)

Inputs

Returns

Errors

How getenv works

• Accepts character vectors ('PATH') or string scalars ("PATH"). Character vector inputs return character vectors; string inputs return string scalars.
• Vectorised calls are supported: pass a string array to receive a string array of values, or a cell array of character vectors to receive a cell array of character vectors.
• When the requested variable is not defined, getenv returns an empty character vector or an empty string scalar (depending on the input type). This matches MATLAB’s “variable not found” semantics.
• Calling getenv with no arguments returns a scalar struct. Field names are the environment variable names; field values are character vectors containing each variable’s value.
• On Windows, environment variable lookups are case-insensitive, mirroring the operating system. On Unix-like systems, lookups are case-sensitive.
• Trailing spaces in character matrix inputs are ignored so that padded rows created with MATLAB’s string manipulation functions remain compatible.
• The builtin rejects non-text inputs (numeric arrays, logicals, GPU tensors, etc.) with a clear MATLAB-style diagnostic.

Does RunMat run getenv on the GPU?

getenv always runs on the CPU. If the argument originates from the GPU—for example, a string scalar produced by an accelerated builtin—RunMat gathers it to host memory before reading the environment. No GPU kernels are launched, and acceleration providers do not need to implement hooks for this builtin.

GPU memory and residency

No. getenv has no GPU implementation and simply queries the host environment. Passing GPU-resident values is supported (RunMat gathers them automatically), but there is no benefit to calling gpuArray yourself.

Examples

Read A Single Environment Variable

homeFolder = getenv("HOME");
disp(homeFolder)

Expected output:

homeFolder =
    "/"

Handle Missing Environment Variables

token = getenv("RUNMAT_TOKEN");
if token == ""
    warning("Token not configured.");
end

Expected output:

Warning: Token not configured.

Fetch Multiple Variables With A String Array

vars = getenv(["PATH", "SHELL"]);
disp(vars)

Expected output:

vars = 1x2 string
    "/usr/local/bin:/usr/bin:/bin"    "/bin/sh"

Use A Cell Array Of Character Vectors

cells = getenv({'HOME', 'PATH'});
disp(cells{1})

Expected output:

/

Inspect All Environment Variables

env = getenv();
disp(env.USER)

Expected output:

env =
  struct with fields:
    HOME: '/'
    PATH: '/usr/local/bin:/usr/bin:/bin'
    USER: 'user'

Cache The Environment For Repeated Access

env = getenv();
resultsFolder = fullfile(env.HOME, "results")

Expected output:

resultsFolder =
    "//results"

Using getenv with coding agents

Open a RunMat example with live inputs, then ask the agent to explain how getenv changes the result.

FAQ

Related Io functions

Open-source implementation

Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how getenv is executed, line by line, in Rust.

• View the source for getenv in Rust on GitHub
• Learn how the RunMat runtime works
• Found a bug? Open an issue with a minimal reproduction.

About RunMat

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