LiuShen/通过HTTP同步时间

sync-time.sh · 1.5 KiB · Bash Raw

#!/bin/bash

set -e

URL="http://www.baidu.com/"
COUNT=10

echo "正在通过百度 HTTP 校准系统时间..."
echo

best_rtt=999999999
best_time=0

for i in $(seq 1 "$COUNT"); do
    start=$(date +%s%3N)

headers=$(curl \
        --noproxy '*' \
        --connect-timeout 3 \
        --max-time 5 \
        -sS \
        -D - \
        -o /dev/null \
        "$URL" 2>/dev/null) || {
        echo "[$i/$COUNT] 请求失败"
        continue
    }

end=$(date +%s%3N)

date_header=$(printf '%s\n' "$headers" |
        grep -i '^Date:' |
        tail -n 1 |
        sed 's/^[Dd]ate:[[:space:]]*//')

if [ -z "$date_header" ]; then
        echo "[$i/$COUNT] 未找到 Date 头"
        continue
    fi

server_sec=$(date -u -d "$date_header" +%s 2>/dev/null) || {
        echo "[$i/$COUNT] 无法解析 Date: $date_header"
        continue
    }

rtt=$((end - start))
    half_rtt=$((rtt / 2))

# Date 头的时间 + 请求往返时间的一半
    estimated_ms=$((server_sec * 1000 + half_rtt))

echo "[$i/$COUNT] RTT=${rtt}ms  Date=$date_header"

if [ "$rtt" -lt "$best_rtt" ]; then
        best_rtt=$rtt
        best_time=$estimated_ms
    fi
done

if [ "$best_time" -eq 0 ]; then
    echo
    echo "错误：无法从百度获取时间"
    exit 1
fi

echo
echo "最佳 RTT: ${best_rtt}ms"

before=$(date '+%Y-%m-%d %H:%M:%S.%3N')

# 设置系统时间
date -u -s "@$(awk "BEGIN {printf \"%.3f\", $best_time / 1000}")" >/dev/null

after=$(date '+%Y-%m-%d %H:%M:%S.%3N')

echo "校时前: $before"
echo "校时后: $after"
echo "校时完成。"

1	#!/bin/bash
2
3	set -e
4
5	URL="http://www.baidu.com/"
6	COUNT=10
7
8	echo "正在通过百度 HTTP 校准系统时间..."
9	echo
10
11	best_rtt=999999999
12	best_time=0
13
14	for i in $(seq 1 "$COUNT"); do
15	start=$(date +%s%3N)
16
17	headers=$(curl \
18	--noproxy '*' \
19	--connect-timeout 3 \
20	--max-time 5 \
21	-sS \
22	-D - \
23	-o /dev/null \
24	"$URL" 2>/dev/null) \|\| {
25	echo "[$i/$COUNT] 请求失败"
26	continue
27	}
28
29	end=$(date +%s%3N)
30
31	date_header=$(printf '%s\n' "$headers" \|
32	grep -i '^Date:' \|
33	tail -n 1 \|
34	sed 's/^[Dd]ate:[[:space:]]*//')
35
36	if [ -z "$date_header" ]; then
37	echo "[$i/$COUNT] 未找到 Date 头"
38	continue
39	fi
40
41	server_sec=$(date -u -d "$date_header" +%s 2>/dev/null) \|\| {
42	echo "[$i/$COUNT] 无法解析 Date: $date_header"
43	continue
44	}
45
46	rtt=$((end - start))
47	half_rtt=$((rtt / 2))
48
49	# Date 头的时间 + 请求往返时间的一半
50	estimated_ms=$((server_sec * 1000 + half_rtt))
51
52	echo "[$i/$COUNT] RTT=${rtt}ms Date=$date_header"
53
54	if [ "$rtt" -lt "$best_rtt" ]; then
55	best_rtt=$rtt
56	best_time=$estimated_ms
57	fi
58	done
59
60	if [ "$best_time" -eq 0 ]; then
61	echo
62	echo "错误：无法从百度获取时间"
63	exit 1
64	fi
65
66	echo
67	echo "最佳 RTT: ${best_rtt}ms"
68
69	before=$(date '+%Y-%m-%d %H:%M:%S.%3N')
70
71	# 设置系统时间
72	date -u -s "@$(awk "BEGIN {printf \"%.3f\", $best_time / 1000}")" >/dev/null
73
74	after=$(date '+%Y-%m-%d %H:%M:%S.%3N')
75
76	echo "校时前: $before"
77	echo "校时后: $after"
78	echo "校时完成。"