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Documentation Index

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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

​
env
Mapping[str, str] | None
Environment variables for the shell. Defaults to empty. The host process environment is not inherited.
​
cwd
str | None
Working directory inside the mount. Defaults to /.
​
timeout_ms
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
""")
​
commands
str
required
Shell script to execute.

​
Response

exec(...) returns ExecResult.
​
stdout
bytes
Standard output bytes.
​
stderr
bytes
Standard error bytes.
​
exit_code
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.