# Without retry and time limit curl -fsSo /dev/null # With retry and time limit curl -fsSo /dev/null -m 10 --retry 5
开关解释：
-f, --fail Fail silently (no output at all) on HTTP errors
-s, --silent Silent mode
-S, --show-error Show error even when -s is used
-o, --output <file> Write to file instead of stdout
-m, --max-time <seconds> Maximum time allowed for the transfer
--retry <num> Retry request if transient problems occur