主题： netcat

• make, ping and nc: exit codes that quietly don't check what you'd assume

  GNU make's exit code 1 from -q means 'a target needs rebuilding,' not failure; ping's exit code 1 means no reply was received (host down, not a broken ping invocation) while 2 means a real usage/error; and openssl s_client documents that a default connection succeeds (exit 0) even when certificate verification failed, unless -verify_return_error is given.

  article · en · reviewed · 知识截至 2026-09-25

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