fs.bash() - Mesa Docs

fs.bash(...) builds a Bash interpreter rooted at the mounted filesystem. Commands run against MesaFS; no host shell is spawned.

bash = fs.bash(cwd="/acme/app", env={"CI": "true"}, timeout_ms=30_000)
result = await bash.exec("rg -n TODO src | head -20")

print(result.exit_code)
print(result.stdout.decode())
print(result.stderr.decode())

Options

Mapping[str, str] | None

Environment variables for the shell. Defaults to empty. The host process environment is not inherited.

str | None

Working directory inside the mount. Defaults to /.

int | None

Per-exec wall-clock timeout in milliseconds. Defaults to 30 seconds.

exec()

exec(commands) takes one string containing one or more shell statements.

result = await bash.exec("""
rg -l integration .
python -m pytest
""")

str

required

Shell script to execute.

Response

exec(...) returns ExecResult.

bytes

Standard output bytes.

bytes

Standard error bytes.

int

Process exit code. 0 indicates success.

Command failures

Command failures usually return a non-zero exit_code; they do not automatically raise.

result = await bash.exec("cat /acme/app/missing.txt")
if result.exit_code != 0:
    print(result.stderr.decode())

Timeouts may surface as either an exception or a non-zero exit depending on where execution is interrupted.

Binary files

Use fs.read(...) for binary files. Text-oriented shell commands such as cat are intended for text output.

​Options

​exec()

​Response

​Command failures

​Binary files

Options

exec()

Response

Command failures

Binary files