What
On Linux, Claude Code can run Bash commands in a sandbox, a restricted environment that limits which files and settings a command can reach. It builds the sandbox with a program called bubblewrap (bwrap), passing every rule as a command-line argument. Claude Code now checks how long that command line gets:
- Too long: the arguments are written to an unnamed temporary file, in the temp folder or
/dev/shm, and handed to bubblewrap from there. - Too many arguments: it stops with a specific error.
- A path containing a NUL byte (an invisible character that cannot appear in arguments): it stops with an error saying so.
- No unnamed file can be opened: it stops with an error saying so.
Why
A sandbox with many allowed or denied paths or environment variables could exceed the operating system's limit on argument length and fail to start. Those setups should now start, and when one can't, the error says why.