What does errno 7 (E2BIG) mean?

E2BIG

What is too large

E2BIG usually occurs during an exec-family call. It refers to the combined argument vector and environment, not simply to “too many command-line arguments”. A single very long argument, an unusually large environment, or a long executable path can trigger the failure. On Linux, the applicable limit is influenced by the process stack resource limit and the kernel also imposes limits on individual strings.

This often appears when a program expands a large list of paths into one command line, serializes structured data into environment variables, or forwards a long build, deployment, or search result directly to a subprocess.

Ways to redesign the call

• Pass bulk data through a file, pipe, socket, or standard input rather than one enormous argument list.
• Batch work into bounded groups and preserve exit-status handling for each batch.
• Measure both argv and inherited environment size; a hidden environment variable can be the difference between success and failure.
• Use the platform’s documented argument-size rules rather than assuming that a limit from one UNIX-like system applies unchanged elsewhere.

References

• Linux manual: execve(2)
• FreeBSD manual: execve(2)
• FreeBSD manual: open(2)

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